AIR TRANSPORTATION SAFETY 
INVESTIGATION REPORT A17C0146
Loss of control and collision with terrain
West Wind Aviation L.P.
Avions de Transport Régional ATR 42-320, C-GWEA
Fond-du-Lac, Saskatchewan
13 December 2017 

ii | TRANSPORTATION SAFETY BOARD OF CANADA
ABOUT THIS INVESTIGATION REPORT
This report is the result of an investigation into a class 2 occurrence. For more information, see the Policy on 
Occurrence Classification at www.tsb.gc.ca
The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing 
transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability. 
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Citation
Transportation Safety Board of Canada, Air Transportation Safety Investigation Report A17C0146 (released 
DD Month YYYY).
Transportation Safety Board of Canada
200 Promenade du Portage, 4th floor
Gatineau QC K1A 1K8
819-994-3741; 1-800-387-3557
www.tsb.gc.ca
communications@tsb.gc.ca
© Her Majesty the Queen in Right of Canada, as represented by the Transportation Safety Board of Canada, 2021
Air transportation safety investigation report A17C0146
Cat. No. TU3-10/17-0146E-PDF
ISBN: 978-0-660-39912-6
This report is available on the website of the Transportation Safety Board of Canada at www.tsb.gc.ca
Le présent rapport est également disponible en français. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | iii
Table of contents
1.0 Factual information ................................................................................................. 1
1.1 History of the flight....................................................................................................................................1
1.1.1 General ...........................................................................................................................................1
1.1.2 Pre-flight planning and dispatch.........................................................................................2
1.1.3 Saskatoon to Fond-du-Lac.....................................................................................................2
1.1.4 On the ground at Fond-du-Lac............................................................................................4
1.1.5 Taxiing for departure from Fond-du-Lac..........................................................................5
1.1.6 Takeoff from Fond-du-Lac .....................................................................................................7
1.1.7 Post-accident events.................................................................................................................8
1.2 Injuries to persons......................................................................................................................................9
1.3 Damage to aircraft.....................................................................................................................................9
1.4 Other damage..............................................................................................................................................9
1.5 Personnel information............................................................................................................................10
1.5.1 General .........................................................................................................................................10
1.5.2 Captain .........................................................................................................................................10
1.5.3 First officer..................................................................................................................................11
1.5.4 Flight attendant ........................................................................................................................11
1.5.5 Flight dispatcher.......................................................................................................................11
1.6 Aircraft information .................................................................................................................................12
1.6.1 General .........................................................................................................................................12
1.6.2 Aircraft ice protection systems ...........................................................................................13
1.6.3 Procedures for atmospheric icing conditions...............................................................14
1.6.4 Take-off performance calculations ...................................................................................15
1.7 Meteorological information.................................................................................................................17
1.7.1 Forecast conditions .................................................................................................................18
1.7.2 Actual conditions .....................................................................................................................20
1.7.3 Aircraft icing conditions ........................................................................................................23
1.8 Aids to navigation....................................................................................................................................29
1.9 Communications.......................................................................................................................................30
1.10 Aerodrome information.........................................................................................................................30
1.10.1 Runway 10/28............................................................................................................................30
1.10.2 Treated gravel guidance........................................................................................................30
1.11 Flight recorders .........................................................................................................................................31
1.11.1 Flight data analysis ..................................................................................................................31
1.12 Wreckage and impact information....................................................................................................35
1.12.1 Occurrence site .........................................................................................................................35
1.12.2 Aircraft wreckage .....................................................................................................................37
1.12.3 Remnants of ice contamination .........................................................................................45
1.13 Medical and pathological information ............................................................................................47
1.14 Fire..................................................................................................................................................................48
1.15 Survival aspects .........................................................................................................................................48
1.15.1 Crashworthiness .......................................................................................................................48
1.15.2 Impact sequence of events ..................................................................................................53 

iv | TRANSPORTATION SAFETY BOARD OF CANADA
1.15.3 Systems to reduce impact injury........................................................................................55
1.15.4 Direct effect on occupants ...................................................................................................60
1.15.5 Effect on evacuation routes .................................................................................................62
1.15.6 Post-impact survival factors.................................................................................................67
1.16 Tests and research ...................................................................................................................................70
1.16.1 TSB laboratory reports ...........................................................................................................70
1.17 Organizational and management information.............................................................................71
1.17.1 Transport Canada.....................................................................................................................71
1.17.2 West Wind Aviation L.P..........................................................................................................92
1.17.3 Previous TSB investigations involving safety management systems and 
oversight 105
1.17.4 TSB recommendations involving safety management systems and oversight
106
1.18 Additional information........................................................................................................................107
1.18.1 Crew resource management.............................................................................................107
1.18.2 Decision making....................................................................................................................111
1.18.3 Aircraft critical surface contamination..........................................................................115
1.18.4 TSB Watchlist..........................................................................................................................128
1.19 Useful or effective investigation techniques ..............................................................................129
1.19.1 TSB pilot survey .....................................................................................................................129
2.0 Analysis ................................................................................................................. 135
2.1 Weather and icing.................................................................................................................................135
2.1.1 Flight planning .......................................................................................................................135
2.1.2 Icing on approach.................................................................................................................136
2.1.3 Icing on the ground .............................................................................................................137
2.2 Inspection and de-icing......................................................................................................................142
2.2.1 Equipment................................................................................................................................142
2.2.2 Inspection before departure.............................................................................................142
2.2.3 Clean aircraft concept .........................................................................................................143
2.2.4 Flight crew decision making.............................................................................................145
2.2.5 Recommendations following pilot survey...................................................................151
2.3 Takeoff and loss of control................................................................................................................152
2.3.1 Performance calculations...................................................................................................152
2.3.2 Aircraft contamination ........................................................................................................153
2.3.3 Loss of control in the roll axis ..........................................................................................154
2.4 Collision with terrain ............................................................................................................................155
2.4.1 Estimation of impact forces ..............................................................................................155
2.4.2 Crashworthiness ....................................................................................................................155
2.4.3 Damage from the impact...................................................................................................156
2.5 Injuries .......................................................................................................................................................159
2.5.1 Serious and fatal passenger injuries..............................................................................159
2.5.2 Other injuries to passengers and flight crew.............................................................159
2.5.3 Infant injury .............................................................................................................................161
2.5.4 Flight attendant injury.........................................................................................................161
2.6 Evacuation................................................................................................................................................161
2.7 Regulatory oversight............................................................................................................................162 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | v
2.7.1 Surveillance planning ..........................................................................................................162
2.7.2 Inconsistent application of policies and procedures ..............................................164
2.7.3 Policies and procedures for Transport Canada inspectors...................................167
2.8 West Wind safety management system.......................................................................................168
2.8.1 West Wind safety management and safety culture ................................................168
2.8.2 Safety risk management.....................................................................................................169
3.0 Findings................................................................................................................. 172
3.1 Findings as to causes and contributing factors.........................................................................172
3.2 Findings as to risk..................................................................................................................................174
3.3 Other findings.........................................................................................................................................176
4.0 Safety action......................................................................................................... 177
4.1 Safety action taken ...............................................................................................................................177
4.1.1 Transportation Safety Board of Canada.......................................................................177
4.1.2 West Wind Aviation L.P.......................................................................................................179
Appendices..................................................................................................................... 182
Appendix A – Transport Canada Civil Aviation’s Safety Management System Framework 
(components and elements).............................................................................................................182
Appendix B – Compliance summary of West Wind assessment made by Transport Canada 
Civil Aviation in September 2016....................................................................................................183
Appendix C – Findings from the 2016 assessment...............................................................................186
Appendix D – Surveillance interval matrix ...............................................................................................189
Appendix E – West Wind National Aviation Safety Information Management System risk 
profile.........................................................................................................................................................190
Appendix F – West Wind safety management system reporting form ........................................196
Appendix G – West Wind flowchart for safety reviews (28 June 2018)........................................197
Appendix H – TSB investigations with findings related to regulatory oversight and safety 
management systems..........................................................................................................................198
Appendix I – West Wind threat and error management briefing reference card....................201
Appendix J – Similar occurrences in Canada involving contaminated critical surfaces during 
takeoff........................................................................................................................................................202
Appendix K – Similar occurrences outside Canada involving contaminated critical surfaces 
during takeoff.........................................................................................................................................203
Appendix L – TSB pilot questionnaire........................................................................................................204
Appendix M – Summary of TSB pilot questionnaire responses ......................................................208
Glossary.......................................................................................................................... 226 



AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 1
AIR TRANSPORTATION SAFETY 
INVESTIGATION REPORT A17C0146
LOSS OF CONTROL AND COLLISION WITH TERRAIN
West Wind Aviation L.P.
Avions de Transport Régional ATR 42-320, C-GWEA
Fond-du-Lac, Saskatchewan
13 December 2017
The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of 
advancing transportation safety. It is not the function of the Board to assign fault or determine 
civil or criminal liability. This report is not created for use in the context of legal, disciplinary or 
other proceedings. See the Terms of use on page ii.
Executive summary
On 13 December 2017, an Avions de Transport Régional ATR 42-320 aircraft (registration 
C-GWEA, serial number 240), operated by West Wind Aviation L.P. (West Wind), was 
scheduled for a series of instrument flight rules flights from Saskatoon through northern 
Saskatchewan as flight WEW282.
When the flight crew and dispatcher held a briefing for the day’s flights, they became aware 
of forecast icing along the route of flight. Although both the flight crew and the dispatcher 
were aware of the forecast ground icing, the decision was made to continue with the day’s 
planned route to several remote airports that had insufficient de-icing facilities. 
The aircraft flew from Saskatoon/John G. Diefenbaker International (CYXE) to Prince Albert 
(Glass Field) Airport (CYPA) without difficulty, and, after a stop of about 1 hour, proceeded 
on toward Fond-du-Lac Airport (CZFD). On approach to Fond-du-Lac Airport, the aircraft 
encountered some in-flight icing, and the crew activated the aircraft’s anti-icing and de-icing 
systems.
Although the aircraft’s ice protection systems were activated, the aircraft’s de-icing boots 
were not designed to shed all of the ice that can accumulate, and the anti-icing systems did 
not prevent ice accumulation on unprotected surfaces. As a result, some residual ice began 
to accumulate on the aircraft. 

2 | TRANSPORTATION SAFETY BOARD OF CANADA
The flight crew were aware of the ice; however, there were no handling anomalies noted 
during the approach. Consequently, they likely did not assess that the residual ice was 
severe enough to have a significant effect on aircraft performance. The crew continued the 
approach and landed at Fond-du-Lac Airport at 1724 Central Standard Time.
According to post-accident analysis of the data from the flight data recorder, the aircraft’s 
drag and lift performance was degraded by 28% and 10%, respectively, shortly before 
landing at Fond-du-Lac Airport. This indicated that the aircraft had significant residual ice 
adhering to its structure upon arrival. However, this data was not available to the flight 
crew at the time of landing.
The aircraft was on the ground at Fond-du-Lac Airport for approximately 48 minutes. The 
next flight was destined for Stony Rapids Airport (CYSF), Saskatchewan, with 3 crew 
members (2 pilots and 1 flight attendant) and 22 passengers on board. 
Although there was no observable precipitation or fog while the aircraft was on the ground, 
weather conditions were conducive to ice or frost formation. This, combined with the 
residual mixed ice on the aircraft, which acted as nucleation sites that allowed the 
formation of ice crystals, resulted in the formation of additional ice or frost on the aircraft’s 
critical surfaces.
Once the passengers had boarded the aircraft, the first officer completed an external 
inspection of the aircraft. However, because the available inspection equipment was
inadequate, the first officer’s ice inspection consisted only of walking around the aircraft 
and looking at the left wing from the top of the stairs at the left rear door, without the use of 
a flashlight on the dimly lit apron. 
Although he was unaware of the full 
extent of the ice and the ongoing 
accretion, the first officer did inform 
the captain that there was some ice on 
the aircraft. The captain did not inspect 
the aircraft himself, nor did he attempt 
to have it de-iced; rather, he and the 
first officer continued with departure 
preparations.
Company departures from remote 
airports, such as Fond-du-Lac, with 
some amount of surface contamination on the aircraft’s critical surfaces had become 
common practice, in part due to the inadequacy of de-icing equipment or services at these 
locations. The past success of these adaptations resulted in this unsafe practice becoming 
normalized and this normalization influenced the flight crew’s decision to depart.
Although the flight crew were aware of icing on the aircraft’s critical surfaces, they decided 
that the occurrence departure could be accomplished safely. Their decision to continue with 
the original plan to depart was influenced by continuation bias, as they perceived the initial 
Figure S1. Ice contamination on leading edge of left 
horizontal stabilizer following the accident (Source: 
Royal Canadian Mounted Police, with TSB annotations) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 3
and sustained cues that supported their plan as more compelling than the later cues that 
suggested another course of action. At 1812 Central Standard Time, in the hours of 
darkness, the aircraft began its take-off roll on Runway 28, and, 30 seconds later, it was 
airborne.
As a result of the ice that remained on the aircraft following the approach and the additional 
ice that had accreted during the ground stop, the aircraft’s drag was increased by 58% and 
its lift was decreased by 25% during the takeoff. 
Despite this degraded performance, the aircraft initially climbed; however, immediately 
after liftoff, the aircraft began to roll to the left without any pilot input. This roll was as a 
result of asymmetric lift distribution due to uneven ice contamination on the aircraft.
Following the uncommanded roll, the captain reacted as if the aircraft was an 
uncontaminated ATR 42, with the expectation of normal handling qualities and dynamic 
response characteristics; however, due to the contamination, the aircraft had diminished 
roll damping resulting in unexpected handling qualities and dynamic response. Although 
the investigation determined that the ailerons had sufficient roll control authority to 
counteract the asymmetric lift, due to the unexpected handling qualities and dynamic 
response, the roll disturbance developed into an oscillation with growing magnitude and 
control in the roll axis was lost.
This loss of control in the roll axis, which corresponds with the known risks associated with 
taking off with ice contamination, ultimately led to the aircraft colliding with terrain 
17 seconds after takeoff.
Figure S2. Aerial view of occurrence site (Source: Royal Canadian Mounted Police, with TSB annotations)
The aircraft collided with the ground in a relatively level pitch, with a bank angle of 30° left. 
As a result of the sudden vertical deceleration upon contact with the ground, the aircraft  

4 | TRANSPORTATION SAFETY BOARD OF CANADA
suffered significant damage, which varied in severity at different locations on the aircraft 
due to impact angle and variability in structural design.
The design standards for transport category aircraft in effect at the time the ATR 42 was 
certified did not specify minimum loads that a fuselage structure must be able to tolerate 
and remain survivable, or minimum loads for fuselage impact energy absorption. As a 
result, the ATR 42 was not designed with these crashworthy principles in mind.
The main landing gear at the bottom of the centre fuselage section was rigid, and, on impact, 
did not absorb or attenuate much of the load. The impact-induced acceleration was not 
attenuated because the landing gear housing did not deform. This unattenuated 
acceleration resulted in a large inertial load from the wing, causing the wing support 
structure to fail and the wing to collapse into the cabin.
The reduced survivable space between the floor above the main landing gear and the 
collapsed upper fuselage caused crushing injuries, such as major head, body, and leg 
trauma, to passengers in the middle-forward left section of the aircraft. Of the 3 passengers 
in this area, 2 experienced, serious life-changing injuries, and 1 passenger subsequently 
died. 
The collapse of part of the floor structure 
compromised the restraint systems, 
limiting the protection afforded to the 
aircraft occupants when they were 
experiencing vertical, longitudinal, and 
lateral forces. This resulted in serious 
velocity-related injuries and impeded 
their ability to take post-crash survival 
actions in a timely manner. Unaware of 
the danger, most passengers in this 
occurrence did not brace for impact. 
Because their torsos were unrestrained, they received injuries consistent with jackknifing 
and flailing, such as hitting the seat in front of them.
As a result of unapproved repairs, the flight attendant seat failed on impact, resulting in 
injuries that impeded her ability to perform evacuation and survival actions in a timely 
manner. 
Although the TSB has previously recommended the development and use of child restraints 
aboard commercial aircraft, planned regulations have yet to be implemented by Transport 
Canada. As a result, the occurrence aircraft was not equipped with these devices, and an 
infant passenger who was unrestrained received flailing and crushing injuries during the 
accident sequence.
By the time the aircraft came to a rest, all occupants had received injuries. Passengers began 
to call for help within minutes of the impact, using their cell phones. Numerous people from 
the nearby community received the messages and quickly set out to help. 
Figure S3. Image of the displaced cabin seats 
(Source: TSB) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 5
The passengers and crew began to evacuate, but they experienced significant difficulties as 
a result of the aircraft damage. It took approximately 20 minutes for the first 17 passengers 
to evacuate, and the remaining passengers much longer; it took as long as 3 hours to 
extricate 1 passenger, who required rescuer assistance.
As a result of the accident, 9 passengers and 1 crew member received serious injuries, and 
the remaining 13 passengers and 2 crew members received minor injuries. One of the 
passengers who had received serious injuries died 12 days after the accident.
There was no post-impact fire, and the emergency locator activated on impact.
Early in this investigation, it became clear that more information was needed to determine 
whether the underlying factors identified in this occurrence were present elsewhere in the 
Canadian commercial aviation industry. 
To assess the risks involved with winter operations at remote northern airports, and 
specifically the risk posed by aircraft taking off with frost, ice, or snow adhering to critical 
surfaces, the TSB conducted an online survey of pilots who were directly exposed to 
operations at remote airports throughout Canada.
The responses received to several questions showed that operations at these remote 
airports were routinely affected by the unavailability and inadequacy of equipment to 
inspect, de-ice, or anti-ice aircraft.
The combined probability and severity of this safety deficiency poses a high risk to 
transportation safety. The risk likely varies from airport to airport, depending somewhat on 
the frequency of operations; however, identifying high-risk locations for immediate 
mitigation can quickly reduce the likelihood of aircraft taking off with frost, ice, or snow 
adhering to any critical surface at those locations.
Transport Canada, air operators, and airport authorities have the capacity to identify 
high‑risk locations, analyze them for hazards and risks, and take mitigating action.
Therefore, in December 2018, the Board recommended that
the Department of Transport collaborate with air operators and airport 
authorities to identify locations where there is inadequate de-icing and anti￾icing equipment and take urgent action to ensure that the proper equipment 
is available to reduce the likelihood of aircraft taking off with contaminated 
critical surfaces.
TSB Recommendation A18-02
The most notable information received from the survey showed that, in the past 5 years, 
74% of pilots had seen aircraft take off with contaminated surfaces, in contravention of 
regulations and the clean aircraft concept. This majority indicates that the issue is systemic, 
rather than isolated to a small number of operators or a select few locations. 
There are many defences in place to ensure the clean aircraft concept is followed, such as 
regulations, company operating manuals, and standard operating procedures. However, all 
of these defences rely singularly on flight crew compliance. As seen in this occurrence, when  

6 | TRANSPORTATION SAFETY BOARD OF CANADA
a single-point compliance adaptation is made, aircraft may depart with contaminated 
surfaces, despite several adequate administrative defences in place. 
To mitigate this hazard, Transport Canada and air operators must take urgent action to 
ensure better compliance.
Accidents related to contaminated aircraft will continue to occur until the industry and the 
regulator approach the issue as systemic and take action to eliminate underlying factors 
that can negatively affect pilot compliance. 
Therefore, in December 2018, the Board recommended that
the Department of Transport and air operators take action to increase 
compliance with Canadian Aviation Regulations subsection 602.11(2) and 
reduce the likelihood of aircraft taking off with contaminated critical 
surfaces.
TSB Recommendation A18-03
When West Wind commenced operations into CZFD in 2014, no effective risk controls were 
in place to mitigate the potential hazard of ground icing. Transportation companies have a 
responsibility to manage safety risks in their operations; however, compliance with 
regulations can provide only a baseline level of safety. When implemented properly, SMS 
enables companies to manage risk effectively and make operations safer. For SMS to be 
effective, it must be supported by a positive safety culture. If a company’s safety culture 
tolerates unsafe practices, there is a risk that these practices will continue and become a 
company norm. 
Safety management is an issue on the TSB’s Watchlist 2020, which identifies the key safety 
issues that need to be addressed to make Canada’s transportation system even safer.
The investigation also revealed a number of instances in which Transport Canada’s
surveillance policies and procedures were inconsistently applied to the oversight of West 
Wind. This is not the first time that such inconsistencies in Transport Canada’s oversight of 
commercial aviation in Canada have been identified. As detailed in the findings of several 
TSB investigations, there have been a number of past examples where Transport Canada
has been slow to either identify or to rectify unsafe conditions at an operator. Transport 
Canada’s inconsistent application of its own policies and procedures for the 2016 
assessment of West Wind and subsequent post-assessment corrective action plan 
verifications, as well as the ad hoc approach to enhanced monitoring, resulted in ineffective 
oversight of an operator that had a history of system-level (i.e., safety management system
[SMS]) and systemic (e.g., operational control) non-compliance issues.
If the application of Transport Canada’s surveillance policies and procedures is inconsistent, 
there is a risk that resulting oversight will be ineffective at ensuring that operators are able 
to effectively manage the safety of their operations.
Regulatory surveillance is also an item on the TSB’s Watchlist 2020. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 1
AIR TRANSPORTATION SAFETY 
INVESTIGATION REPORT A17C0146
LOSS OF CONTROL AND COLLISION WITH TERRAIN
West Wind Aviation L.P.
Avions de Transport Régional ATR 42-320, C-GWEA
Fond-du-Lac, Saskatchewan
13 December 2017
The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of 
advancing transportation safety. It is not the function of the Board to assign fault or determine 
civil or criminal liability. This report is not created for use in the context of legal, disciplinary, or 
other proceedings. See the Terms of use on page ii.
1.0 FACTUAL INFORMATION
1.1 History of the flight
1.1.1 General
On 13 December 2017, the West Wind Aviation L.P. (West Wind) Avions de Transport 
Régional (ATR) 42-320 aircraft (registration C-GWEA, serial number 240), was conducting 
 1 International Civil Aviation Organization (ICAO), Annex 13 to the Convention on International Civil Aviation, 
Aircraft Accident and Incident Investigation, 12th Edition (July 2020), paragraph 5.12.
Annex 13 to the Convention on International Civil Aviation requires States conducting accident 
investigations to protect cockpit voice recordings.1 Canada complies with this requirement by making all 
on-board recordings—including those from cockpit voice recorders (CVR)—privileged in the Canadian 
Transportation Accident Investigation and Safety Board Act. While the TSB may make use of any on-board 
recording in the interests of transportation safety, it is not permitted to knowingly communicate any 
portion of an on-board recording that is unrelated to the causes or contributing factors of an accident or 
to the identification of safety deficiencies.
The reason for protecting CVR material lies in the premise that these protections help ensure that pilots 
will continue to express themselves freely and that this essential material is available for the benefit of 
safety investigations. The TSB has always taken its obligations in this area very seriously and has 
vigorously restricted the use of CVR data in its reports. Unless the CVR material is required to both 
support a finding and identify a substantive safety deficiency, it will not be included in the TSB’s report.
To validate the safety issues raised in this investigation, the TSB has made use of the available CVR 
information in its report. In each instance, the material has been carefully examined in order to ensure 
that it is required to advance transportation safety. 

2 | TRANSPORTATION SAFETY BOARD OF CANADA
West Wind flight 282 (WEW282), which consisted of a series of instrument flight rules 
flights through northern Saskatchewan.
WEW282 originated from Saskatoon/John G. Diefenbaker International Airport (CYXE), and
was scheduled to make stops at Prince Albert (Glass Field) Airport (CYPA), Fond-du-Lac 
Airport (CZFD), Stony Rapids Airport (CYSF), Wollaston Lake Airport (CZWL), Points North 
Landing Airport (CYNL), and back to CYPA before terminating at CYXE.
WEW282 was being operated under Subpart 705 of the Canadian Aviation Regulations
(CARs).2 The flight was chartered by Transwest Air, a West Wind subsidiary, to transport 
overflow passengers and cargo from a scheduled flight operated by Transwest Air that was 
flying the same route ahead of WEW282.
1.1.2 Pre-flight planning and dispatch
At 1215,3 a West Wind dispatcher began organizing the WEW282 operational flight plans 
(OFPs) for all 7 segments of the planned flight. WEW282 was planned to depart from CYXE 
at 1430 with no passengers on board and a fuel load of 8200 pounds. The plan was for 
WEW282 to complete the scheduled route without taking on additional fuel at any stops en
route. At 1225, the OFP for the occurrence flight was completed.
The WEW282 crew, which comprised 2 pilots and 1 flight attendant (FA), reported for duty 
at the West Wind hangar at CYXE at approximately 1330. The FA proceeded with her duties 
to get the aircraft cabin ready for the flight, while the captain and first officer (FO) met with 
the dispatcher for a pre-flight briefing.
The briefing consisted of all of the items required for the flight,4 including the current
weather; aerodrome and area forecasts for takeoff, en route, destination, alternate and the 
return trip segments; and the forecast icing in the area of operations. 
1.1.3 Saskatoon to Fond-du-Lac
For the departure from CYXE, the captain was seated in the left seat and was the pilot flying 
(PF). The FO, who was also captain-qualified, was seated in the right seat and was the pilot 
not flying (PNF). The pilots were planning to switch seats and flying duties for the rest of 
the day after landing at CYSF.
WEW282 departed CYXE at 1406 and, following an uneventful flight, arrived at CYPA at 
1442. WEW282 departed CYPA at 1532, with 15 passengers on board, and was cleared by 
 2 Subpart 705 (airline operations) includes air transport services involving an airplane “that has a MCTOW 
[maximum certified takeoff weight] of more than 8 618 kg (19,000 pounds) or for which a Canadian type 
certificate has been issued authorizing the transport of 20 or more passengers” (Source: Transport Canada, 
SOR/96-433, Canadian Aviation Regulations, subsection 705.01).
3 All times are Central Standard Time (Coordinated Universal Time (UTC) minus 6 hours).
4 West Wind, Flight Dispatch Operational Control Manual, Revision no. 4 (01 April 2015), Chapter 5, pp. 14-15. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 3
air traffic control (ATC) to fly direct to CZFD at flight level (FL) 220.
5 The takeoff, climb, and 
cruise segments of the flight were uneventful.
At 1657, WEW282 was in cruise flight approximately 86 nautical miles (NM) south of CZFD 
when ATC issued a clearance to depart controlled airspace and provided the crew with the 
1654 automated weather observation system (AWOS) aerodrome routine meteorological
report (METAR) for CYSF (see section 1.7.2.1 Aerodrome routine meteorological reports).
At 1658, the crew of a Saab 340 operating as Transwest Air flight 280 (TW280) informed
WEW282 that TW280 was also inbound to CZFD and was approximately 6 minutes ahead.
Shortly thereafter, the crew of another aircraft, a Beechcraft 1900 operating as WEW660, 
announced that they were also inbound to CZFD and were ahead of TW280.
At 1702 civil twilight ended, and night began. Four minutes later, the WEW282 flight crew 
briefed for the RNAV (GNSS)6 instrument approach procedure for landing on Runway 28. At 
1710, the crew of TW280 broadcasted that they were 6 miles to the south of the airport and 
had the runway in sight. 
At 1713:15, while WEW282 was descending through 8100 feet,
7 it began to encounter in￾flight icing. The captain instructed the FO to increase ice protection from Level 1 to Level 2
(see section 1.6.2 Aircraft ice protection systems), and the aircraft’s torque was increased 
from less than 5% to 50%.
Thirty seconds later, while the aircraft was descending through 7600 feet, the master 
caution single chime sounded and the CAUTION and ICING8 alert lights illuminated,
indicating that ice accretion was detected on the ice probe. Five seconds after icing 
conditions were detected by the ice detector, the captain instructed the FO to engage Level 
3 ice protection (pneumatic airframe de-icing systems). 
Three minutes after the probe initially detected icing conditions, as the aircraft was 
descending through 4700 feet, the torque was reduced to 35% and the aircraft performance 
 5 Flight level (FL) is the “altitude expressed in hundreds of feet indicated on an altimeter set to 29.92 in. of 
mercury or 1013.2 mb.” In this case, FL220 means 22 000 feet above mean sea level. (Source: Transport 
Canada, Advisory Circular [AC] 100-001: Glossary for Pilots and Air Traffic Services Personnel [09 April 2020], 
at https://www.tc.gc.ca/en/services/aviation/reference-centre/advisory-circulars/ac-100-001.html [last 
accessed 17 June 2021])
6 RNAV refers to area navigation. An RNAV (GNSS) approach indicates a procedure requiring GNSS (global 
navigation satellite system).
7 All altitudes are in feet above sea level (ASL), unless otherwise noted.
8 The amber ICING alert light on the cockpit ice detection panel illuminates to indicate the presence of ice 
accretion. 

4 | TRANSPORTATION SAFETY BOARD OF CANADA
monitoring (APM)9 system’s DEG PERF light illuminated.
10 The ICING light remained 
illuminated. 
At 1719:50, as the aircraft was established on the extended runway centreline, the APM’s
INC SPD (increase speed) flashing light illuminated.
11 The airspeed was 156 knots indicated 
airspeed (KIAS), and the descent rate was approximately 250 fpm. Shortly thereafter, the 
torque increased to 55% and airspeed increased to 167 KIAS. Fourteen seconds after the 
initial illumination, the INC SPD light extinguished; however, the APM’s DEG PERF light 
remained illuminated.
At 1720:43, while the aircraft was descending through 3000 feet, the flaps were set to 15° 
and the landing gear was extended. At the same time, the APM’s DEG PERF light
extinguished.
12 The descent rate increased to 750 fpm. 
Forty seconds later, while the aircraft was descending through 2900 feet, the ICING light 
also extinguished and remained off for the remainder of the flight, indicating that ice was no
longer accreting on the probe. Flaps were extended to 30° at 1721:57.
At 1722:23, while the aircraft was descending through 2100 feet, both pilots acquired visual 
reference with the runway, and 1 minute later, after letting the de-icing system run through 
1 more cycle, the crew returned ice protection to Level 1. Following this selection, the crew 
briefly discussed the presence of residual ice on the aircraft.
While the aircraft was descending through 1450 feet, the captain disengaged the autopilot. 
No anomalies were noted during the remainder of the approach, and the aircraft landed on 
Runway 28 at 1724:44.
1.1.4 On the ground at Fond-du-Lac
At 1726:19, WEW282 cleared the runway and taxied to the apron. WEW660 already had its 
engines running and was ready to start taxiing for departure, which it did immediately after 
WEW282 taxied past, and subsequently departed from Runway 10.
At 1727:42, once the aircraft was stopped on the apron, the flight crew of WEW282 engaged
the parking brake, shut down the left engine, and activated the propeller brake13 for the 
 9 The aircraft performance monitoring (APM) system monitors aircraft drag in icing conditions and changes to 
cruise speed to alert the crew of a risk of severe icing conditions and abnormal speed decreases. It also 
checks that the minimum severe icing speed is respected. (Source: Avions de Transport Régional, ATR 42
Flight Crew Operating Manual, Revision no. 41 [August 2015], Part 2, Chapter 02, section 21, p. 5.)
10 The amber DEG PERF light illuminates to alert the crew to a degradation in performance as the result of 
increased drag. (Source: Ibid., p. 13.)
11 The amber INC SPD flashing light illuminates to alert the crew to a further degradation of performance that 
requires higher airspeeds to maintain safer stall margins. (Source: Ibid., p. 13.)
12 The APM alerts are inhibited when the flaps are configured to anything other than 0°. A degraded 
performance condition may still exist. (Source: Ibid., p. 10.)
13 The propeller brake allows the engine to continue to run while keeping the propeller stationary. This is 
referred as “hotel mode.” 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 5
right engine. Eight of the 15 passengers on board were destined for Fond-du-Lac and 
disembarked; the other 7 were destined for later stops and remained on board. 
The flight crew then left the cockpit to assist with loading. At about 1745, loading was 
completed, and the captain returned to the cockpit and began programming the next flight 
into the flight management system (FMS) and calculating the weight and balance. The FO 
proceeded to the airport terminal building to escort passengers to the aircraft.
At 1754, TW280 taxied away from the apron and subsequently departed from Runway 28.
The FO of WEW282 then escorted 15 passengers to the aircraft; these passengers included 
1 child and 1 passenger in a wheelchair.
Once the passengers had boarded the aircraft, the FO walked around the aircraft to conduct 
a visual external inspection. Although this inspection was accomplished during the hours of 
darkness on the dimly lit apron and without the use of a flashlight, the FO observed
contamination on the nose of the aircraft and some residual ice on the leading edges of the 
wings, engine intakes, and the vertical stabilizer. The FO completed the external inspection 
by visually examining the left wing from the top of the airstair door on the left side of the 
rear cabin.
By 1803:40, the FO had returned to the cockpit. He told the captain that he noticed that 
there was more ice outside than he had originally thought. The captain, who was working 
on departure calculations, acknowledged, and then the FO pointed out that ice was also 
sticking to the power lines. The captain again acknowledged, and, referring to the ice on the 
power lines, the FO said that the ice was on the aircraft as well. The captain responded in a 
way that indicated he was not concerned. The discussion lasted for 9 seconds before the 
captain returned to his calculations.
Within 15 seconds from the beginning of the icing discussion, the captain told the FO that 
they had 7 more passengers than anticipated, and instructed the FO to begin the before￾start checklist. 
1.1.5 Taxiing for departure from Fond-du-Lac
The proposed flight plan for WEW282 for the 42 NM eastbound flight from CZFD to CYSF 
was to fly direct at an altitude of 7000 feet. 

6 | TRANSPORTATION SAFETY BOARD OF CANADA
At 1805, while the before-start check was being 
conducted, the captain briefed the normal speeds 
on the 35 000-pound take-off card (Figure 1) 
because the aircraft was heavier than originally 
planned. The crew then set the speed bugs as per 
the normal (non-icing) numbers on the card: 
V1/VR 100 KIAS,
14 V2 106 KIAS,
15 VL0 127 KIAS,
16
and VL0 icing 147 KIAS.17
By 1806:35, the right engine propeller brake was 
released, the left engine was started, and the 
aircraft began to taxi for Runway 28.
The taxi and backtrack for Runway 28 was 
slightly longer than that for Runway 10, and the 
takeoff was in the opposite direction of the 
planned flight. However, the captain discussed
that although the winds were light, they were favouring Runway 28, and because the
aircraft was heavier than originally planned, it would be better to use the into-wind runway. 
The FO responded that he agreed and that, with the amount of ice that was on the aircraft,
he would rather have a couple of knots of headwind. 
As part of the taxi checks, at 1807:45 the captain conducted the take-off briefing. During this 
briefing, the captain mentioned the known potential threat of departing toward an area of 
darkness, and how they would mitigate this.
The captain called for before-takeoff checks at 1809:07. In response to the checklist item 
regarding anti-ice, the captain decided that Level 1 icing protection was sufficient for 
takeoff. 
At 1810:48, the aircraft was stopped on the threshold of Runway 28, in position for takeoff.
Ten seconds later, while completing the before-takeoff checks, the captain visually observed
the left spoiler from the cockpit window and acknowledged having it in sight. Shortly 
afterward, the FO visually observed the right spoiler from the cockpit window and reported 
 14 V1 is the speed at which the pilots must make the decision following failure of an engine to either continue 
the takeoff or stop the aircraft; VR is the speed at which rotation is initiated. In this case, both speeds are the 
same. (Source: Avions de Transport Régional, ATR 42 Airplane Flight Manual, Revision no. 24 [July 2013], 
Chapter 06, section 03, p. 1.)
15 V2 is the takeoff safety speed. (Source: Ibid., p. 1.)
16 VL0 was a term used by West Wind instead of VmLB, which is “the absolute minimum maneuver speed […] 
used in flaps 0 configuration to obtain the best climb gradient.” (Source: Avions de Transport Régional, ATR 
42 Flight Crew Operating Manual, Revision no. 41 [August 2015], Part 2, Chapter 02, section 01, p. 2.)
17 VL0 icing was a term used by West Wind instead of VmLB to indicate the flaps 0 minimum manoeuvre speed in 
icing conditions. (Source: Ibid., p. 2.)
Figure 1. West Wind ATR 42 take-off card 
35 000 pounds (Source: West Wind Aviation 
L.P.) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 7
that he had it in sight, but just barely. This spoiler check is considered the last-chance
inspection to check for surface contamination before takeoff.
Between 1811:33 and 1811:58, the crew completed the line-up checks and then made a
traffic advisory broadcast on the aerodrome traffic frequency to report that they were 
rolling for departure from Runway 28. This was the last radio transmission from the 
WEW282 flight crew before the occurrence.
1.1.6 Takeoff from Fond-du-Lac
At 1812:01, the captain began to increase power, and WEW282 commenced the take-off 
roll. As instructed by the captain, the FO set the power to the appropriate take-off setting 
and, at 1812:18, announced that the airspeed was increasing through 70 KIAS. 
As the aircraft reached a speed of 100 KIAS at 18:12:29, the FO announced that the speed 
had reached V1 and VR, and the captain began to rotate the aircraft to 10° of nose-up pitch.
The aircraft lifted off the runway at 1812:31, and, within a second, the FO announced a 
positive rate of climb, which was immediately followed by the captain instructing the FO to 
raise the gear and engage the yaw damper. The airspeed was 108 KIAS, and the FO raised
the landing gear selector. At that same moment, the aircraft began an uncommanded roll to 
the left.
The captain immediately applied control inputs to stop the roll, which increased to full right 
aileron, and the aircraft quickly went from a left bank to right bank. The captain responded 
to the right bank with partial left aileron input, and the aircraft quickly went into a left bank. 
At 1812:37, while applying correction for the second roll to the left, which again increased 
to full right aileron, the captain asked if this was being caused by the ice. These oscillations 
continued, and their severity began to increase.
At 1812:39, while the aircraft was reaching a peak left bank of 32.7°, the aircraft’s pitch 
increased through 20.7°, the angle of attack (AOA) vane angle increased through 18.4°, and 
the stall warning sounded for 1.6 seconds. The FO announced the stall, and the captain 
moved the elevator from 9.5° nose up to 14.5° nose down. 
At 1812:42, with the aircraft now in a 24.0° right bank, it reached its peak height of 142 feet 
above ground at 107 KIAS. The captain called for maximum power, and the FO pushed both 
power levers to the maximum. Airspeed began to increase.
At 1812:46, the stall warning sounded again, and the aircraft’s enhanced ground proximity 
warning system (EGPWS) announced a BANK ANGLE warning. The aircraft was rolling left, 
through 40.0° of left bank, with full right aileron applied, at 122 KIAS, and beginning to 
descend.
One second later, the aircraft’s left bank reached its peak of 63.3°, and the aircraft began to 
contact trees. The stall warning sounded briefly. 

8 | TRANSPORTATION SAFETY BOARD OF CANADA
At 1812:48 the aircraft collided with the ground in a 32.0° left bank with approximately 4°
of nose-up pitch. The aircraft slid along the ground for about 9 seconds and came to a rest at 
1812:57 (Figure 2).
Figure 2. Aircraft height above ground level (AGL), indicated airspeed (IAS), pitch, and bank, 
during the occurrence takeoff and ground collision (Source: Google Earth, with TSB annotations)
1.1.7 Post-accident events
At 1812:57, the captain and FO, still strapped into their seats with the cockpit section sitting 
on its right side, began to carry out emergency procedures. To ensure the engines were shut 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 9
down, the FO pulled the right engine fire handle at 1813:25 and the left fire handle shortly 
afterward.
At 1814:39, the flight crew carried out the checklist for ON GROUND ENG FIRE OR SEVERE 
MECHANICAL DAMAGE and set the emergency locator transmitter to ON. After completing 
that checklist, the pilots determined there was no communication between the cabin and 
the flight deck, and chose not to carry out the ON GROUND EMERGENCY EVACUATION
checklist. 
At 1817, the FO called West Wind dispatch on his cellphone to let them know about the 
accident and to request assistance. A West Wind flight follower who received the phone call
activated the company emergency response plan.
1.2 Injuries to persons
All 22 passengers and 3 crew members were injured (Table 1). Many were rendered 
temporarily unconscious. The captain and 9 passengers were seriously injured, and 1 of the 
seriously injured passengers died 12 days after the accident as a result of the injuries 
received.
Table 1. Injuries to persons
Degree of 
injury
Crew Passengers Persons not on 
board the 
aircraft
Total by injury
Fatal 0 1 – 1
Serious 1 8 – 9
Minor 2 13 – 15
Total injured 3 22 – 25
For more detailed information on injuries, see section 1.15.4 Direct effect on occupants.
1.3 Damage to aircraft
The aircraft was destroyed.
Further detailed description of damage to specific structures and components is provided in 
section 1.12 Wreckage and impact information.
1.4 Other damage
The aircraft collided with trees and the ground in a forested area, causing localized 
disruption to the forest in the impact zone and debris field. 
The aircraft departed CZFD with approximately 3068 L of Jet A fuel on board; however, only 
1200 L were recovered following the accident. The remaining 1800 L were spilled on the 
forest floor during the accident sequence.  

10 | TRANSPORTATION SAFETY BOARD OF CANADA
1.5 Personnel information
1.5.1 General
Records indicate that the captain, FO, FA, and dispatcher were all certified and qualified 
with respect to their active roles, in accordance with existing regulations.
Table 2. Personnel information
Captain First officer
Pilot licence Airline transport 
pilot licence (ATPL)
Airline transport 
pilot licence (ATPL)
Medical expiry date 01 June 2018 01 April 2018
Total flying hours 5990 15 769
Flight hours on type 1500 7930
Flight hours in the 7 days before the occurrence 18.5 7.0
Flight hours in the 30 days before the occurrence 94.3 77.6
Flight hours in the 90 days before the occurrence 212.3 200.5
Flight hours on type in the 90 days before the occurrence 212.3 200.5
Hours on duty before the occurrence 4.7 4.7
Hours off duty before the work period 19.5 19.5
1.5.2 Captain
The captain was hired by West Wind on 25 June 2010. In November 2015, he began 
operating the ATR 42 as an FO and, by July 2017, he was promoted to captain. He had 
approximately 400 hours as pilot-in-command (PIC)18 on the ATR 42.
The captain was on reserve duty the day before the occurrence but did not fly. On 
13 December 2017, he began duty at 1330 and reported feeling rested. The planned duty 
period was about 9 hours. Fatigue was not considered a contributing factor in this 
occurrence.
A review of training records determined that the captain had completed all required 
company initial and recurrent training, including:
• Emergency/Fire Evacuation Procedures – 07 May 2016
• SMS [Safety Management Systems] for Employees – 23 January 2017
• Ground and In-Flight Icing Training – 26 September 2017
• ATR 42 Recurrent Ground School – 04 June 2017
• Crew Resource Management (CRM) – 06 June 2017
 18 Pilot-in-command refers to the pilot who has the responsibility of the flight and has final authority on the 
flight deck. In this report, the term “pilot-in-command” is used in a general sense and the term “captain” is 
used to refer to the pilot-in-command of this particular flight.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 11
1.5.3 First officer
The FO was hired by West Wind on 15 June 2000 as an FO on the British Aerospace BAE-31
Jetstream. In November 2005, he began flying the ATR 42 as an FO. In May 2011, he was 
promoted to a captain position on the ATR 42. On the day of the occurrence, the FO, who 
usually flew as a captain, was scheduled to fly as an FO due to the unavailability of FOs.
The FO was on reserve duty the day before the occurrence but did not fly. On 13 December 
2017, he began duty at 1330 and reported feeling rested. The planned duty period was 
about 9 hours. Fatigue was not considered a contributing factor in this occurrence.
A review of training records determined that the FO had completed all required company 
initial and recurrent training, including:
• Emergency/Fire Evacuation Procedures – 01 June 2016
• SMS for Employees – 29 January 2017
• Ground Icing Training – 23 September 2017
• In-Flight Icing Training – 30 September 2017
• ATR 42 Recurrent Ground School – 04 June 2017
• Crew Resource Management – 17 June 2017
1.5.4 Flight attendant
The FA was hired by West Wind on 09 February 2015 and completed initial FA training on 
16 March 2015. She then completed line indoctrination on the ATR 42 on 26 March 2015. In 
March 2017, the FA completed annual FA recurrent training, which included CRM training.
The FA had been on leave for 5 weeks before the accident. West Wind required the FA to 
review emergency procedures before returning to work. The FA was on reserve duty the 
day before the occurrence but did not fly. The occurrence flight was the second day back to 
work for the FA.
On 13 December 2017, the FA began duty at 1330 and reported feeling rested. The planned 
duty period was about 9 hours. Fatigue was not considered a contributing factor in this 
occurrence.
1.5.5 Flight dispatcher
The dispatcher was hired by West Wind in 2012 in another role and completed initial
dispatch training in November 2017. 
On 13 December 2017, the dispatcher began duty at 1200 and reported feeling rested. The
planned duty period was about 8 hours. Fatigue was not considered a contributing factor in 
this occurrence. 

12 | TRANSPORTATION SAFETY BOARD OF CANADA
1.6 Aircraft information
1.6.1 General
The ATR 42-320 is a pressurized twin-engine turboprop produced by ATR and type￾certified in the transport category.
The occurrence aircraft was manufactured in 1991 and acquired by West Wind in 2012. It
was configured with 44 passenger seats.
Table 3. Aircraft information
Manufacturer ATR-GIE Avions de Transport Régional (ATR) 
(formerly Aerospatiale)
Type, model, and registration ATR 42-320, C-GWEA
Year of manufacture 1991
Serial number 240
Certificate of airworthiness / flight permit issue date 04 March 1988
Total airframe time 26 481.3 hours, 32 051 cycles
Engine type (number of engines) Pratt & Whitney Canada PW121 (2)
Propeller/rotor type (number of propellers) Hamilton Sundstrand Model 14SF-5 (2)
Maximum allowable take-off weight 37 258 pounds
Recommended fuel type(s) MIL-T-5624, Grade JP5, AST-MD-1655 Grades 
JET A, Jet A1
Fuel type used Jet A
The ATR 42-320 is built with the wing mounted at the top of the fuselage. The empennage is 
configured with the horizontal tail surface mounted on the top portion of the vertical 
stabilizer, also known as a T-tail. The height above ground of the wings is 3.76 m and of the 
horizontal tail surface is 7.75 m. These horizontal surfaces have a combined surface area of 
approximately 66.2 m² (Figure 3). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 13
Figure 3. Illustration of ATR 42 profile (Source: Avions de Transport Régional, ATR 42 Airplane Flight 
Manual, Revision no. 24 [July 2013], Chapter 01, section 03, p. 1, with TSB annotations)
1.6.2 Aircraft ice protection systems
The ATR 42 is equipped with an icing advisory system. This system includes an ice detector 
located on the left wing, an icing evidence probe located on the lower frame of the left 
cockpit side window and visible to both pilots, and an indicator light located on the central 
annunciator panel.
The ATR 42 ice protection system permits the aircraft to operate in icing conditions. Ice 
protection is provided to critical areas of the aircraft by 2 aircraft systems: an electrical 
system that provides heat to the pitot and static ports, AOA vanes, windshields, propellers, 
and flight control horns; and a pneumatic system that provides bleed air from the engines to 
the outboard leading-edge wing de-icing boots, horizontal stabilizer leading-edge boots, 
engine air intakes, and engine gas path (Figure 4). 

14 | TRANSPORTATION SAFETY BOARD OF CANADA
The ice protection system is 
controlled by an overhead panel 
in the cockpit. The panel is divided 
into 3 segments that allow the 
flight crew to select the desired 
level of protection. Level 1, 2, and 
3 are terms used by West Wind to 
describe the icing protection that 
has been selected on the aircraft.
Level 1, or “permanent 
protection,” includes the probes, 
ports, and front windows. Level 2,
or “anti-icing” adds propellers, 
horns, side windows, and engine 
intakes. Level 3 or “de-icing” adds
all remaining protection, including 
wings and stabilizer. 
1.6.3 Procedures for atmospheric 
icing conditions
When atmospheric icing 
conditions are present, aircraft 
performance can be degraded. To 
account for this, specific 
procedures must be followed. These procedures normally include engaging icing protection 
and adjusting speeds to ensure that margins of safety are maintained. The change to these 
speeds can also have an effect on take-off and landing distances.
The limitations section in the ATR 42 Airplane Flight Manual (AFM) states that 
Atmospheric icing conditions exist when :
– OAT [outside air temperature] on the ground and for take-off is at or below 
10° C or when TAT [total air temperature] in flight is at or below 10°C,
– and visible moisture in any form is present (such as clouds, fog with visibility 
of less than one mile, rain, snow, sleet and ice crystals). 19
The normal procedures section describes what must be done when these conditions are 
present:
Procedure for operation in atmospheric icing conditions :
• As soon as and as long as atmospheric icing conditions exist, the following 
procedures must be applied :
ANTI–ICING (propellers, horns, side–windows, engines)………………………………ON
 19 Avions de Transport Régional, ATR 42 Airplane Flight Manual, Revision no. 24 (July 2013), Chapter 02, 
section 06, p. 1.
Figure 4. Diagrams showing ice- and rain-protected areas of 
the ATR 42 (Source: Avions de Transport Régional, ATR 42 
Flight Crew Operating Manual, Revision no. 41 [August 2015],
Part 1, Chapter 13, section 10, p. 2) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 15
PROP MODE SEL...............................................................................................According to SAT 
NP set ..................................................................................................................................set ≥ 86 %
Minimum maneuver / operating icing speed.....................BUGGED AND OBSERVED
ICE ACCRETION..............................................................................................................MONITOR
NOTE : horns anti-icing selection triggers the illumination of the ”ICING AOA” green 
light and lowers the AOA stall warning threshold.
20
1.6.4 Take-off performance calculations
When determining take-off performance calculations, numerous factors must be 
considered, including take-off weight, wind, temperature, pressure altitude, equipment in 
use, icing conditions, runway length available, runway surface and slope, and runway 
surface contamination. Because most of these factors cannot be changed, take-off
performance calculations normally result in adjustments to the take-off weight to 
accommodate for the other factors. For example, procedures require increased take-off 
speeds in atmospheric icing conditions, which result in longer take-off distances and greater 
accelerate-stop distances. 
Similarly, runways that are softer, such as those made of gravel or those that are 
contaminated, result in performance degradation, requiring greater take-off distances than 
those with dry, hard surfaces. At locations where runways are relatively short, the 
calculated take-off distances can be greater than the distances available, necessitating a 
reduction in take-off weight to accommodate. The specific details of how to calculate this 
performance, and the resulting accommodations, are published in the AFM.
1.6.4.1 Selection of icing speeds
When aircraft are designed, they must meet airworthiness standards in order to receive 
type certification. Many of those standards are related to take-off performance and include 
ensuring that obstacle clearance is maintained throughout the take-off path, even in the 
event of an engine failure while operating in icing conditions.
The standards contained in Chapter 525 – Transport Category Aeroplanes of the 
Airworthiness Manual, define the limits of this take-off path:
The take-off path extends from a standing start to a point in the take-off at which the 
aeroplane is 1,500 feet above the take-off surface […]21
Thus, when determining whether icing procedures should be used on departure, flight 
crews must consider that the take-off path continues from the ground up to 1500 feet AGL.
This flight path duration is also part of the certification standards,
22 which ensure that 
 20 Ibid., Chapter 03, section 04, p. 1.
21 Transport Canada, Airworthiness Manual Chapter 525 – Transport Category Aeroplanes, section 525.111–
Take-off Path, paragraph (a).
22 Ibid., Appendix C, Part II. 

16 | TRANSPORTATION SAFETY BOARD OF CANADA
aircraft are designed to meet obstacle clearance requirements when the aircraft enters icing 
conditions during takeoff. 
Even though the standards and regulations state that the take-off path continues to 
1500 feet, there is no specific guidance in the manufacturer’s official documents (AFM, 
Flight Crew Operating Manual [FCOM]), West Wind manuals, or in the Transport Canada
Aeronautical Information Manual (TC AIM) with respect to the use of icing procedures if 
icing conditions are perceived to exist at any point below this altitude.
The only reference identified during the investigation that suggested the take-off path 
extended up to the 1500 feet limit for the purposes of icing procedures was found in the 
Cold Weather Operations brochure published by ATR, which states the following: 
Take-off in atmospheric icing conditions
According to FCOM 2.02.08 the crew must select “anti-icing” ON to prevent ice 
accretion on airframe. As soon as “anti-icing” is ON, what [sic] is confirmed by the 
“ICING AOA” light ON, the crew must monitor speed to stay in the flight envelope.
Furthermore takeoff speeds are increased while “ICING AOA” light is ON, leading to 
performance reduction.
NOTE: The take-off is assumed to last until the aircraft has reached 1500ft AGL or 
when 10 minutes elapsed from brakes release, whichever occurs first.23
Although there were a few clouds reported below 1500 feet at the time of departure from 
CZFD, there was no active precipitation observed while the aircraft was on the ground. As a 
result, the crew determined that icing procedures were not required, chose to leave anti￾icing off (although Level 1 was active), and selected non-icing speeds for the takeoff.
Additionally, because the crew determined that atmospheric icing conditions did not exist, 
and non-icing speeds were used, the calculated take-off distance required was not 
increased, and take-off weights were not decreased to accommodate. 
1.6.4.2 Unpaved runways
To provide guidance to those operating on unpaved surfaces, Transport Canada (TC)
published Advisory Circular (AC) 700-011 in 2012. With regard to operations in winter, the
advisory states:
(1) During periods of extended and deep frost, unpaved surfaces such as gravel 
runways can have strength characteristics similar to those of runways with 
paved hard surfaces. Operational experience has indicated that two weeks of 
ambient temperatures of −20°C or lower may be necessary for an unpaved 
runway to achieve strength similar to a paved hard surfaced runway. Once 
frozen solid, the runway will remain in this state, until ambient temperatures 
increase to above freezing.
[…]
 23 Avions de Transport Régional – ATR Customer Services, Cold Weather Operations: Be Prepared for Icing
[brochure] (March 2011), Chapter F, subsection F.5.1. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 17
(3) All applicable AFM (Aircraft Flight Manual) performance factors should be 
applied for frozen unpaved runway operations. The performance factors for 
operations contained in CASS (Commercial Air Services Standard) 724.44(3) 
should be applied when operating in accordance with this standard.24
The runway surface at CZFD is treated gravel (see specific details in section 1.10 Aerodrome
information). The ATR 42 AFM contains performance supplements for operations on dry 
unpaved runways, but not for operations on frozen unpaved surfaces.
Without specific performance penalties published by the manufacturer, and with guidance 
stating that frozen unpaved surfaces had qualities similar to paved surfaces, the operator 
and flight crew determined that a performance penalty was not required for the departure.
1.6.4.3 Runway surface contamination
Similar to the performance degradation that results from unpaved runways, surface 
contamination such as water, ice, or snow, can affect aircraft take-off performance.
At 0700 on the morning of the occurrence, CZFD issued a runway surface condition report
for Runway 10/28 that recorded the conditions as 60% bare and dry and 40% compacted 
snow patches. A similar report was issued the following morning, after the accident;
however, this report recorded that the compacted snow patches were no longer present.
The ATR 42 AFM states that, if more than 25% of the runway is covered by compacted 
snow, it should be considered contaminated, and this condition is to be used when 
determining aircraft performance.25
Given that the most recent runway surface condition report had been issued 11 hours 
before the time of departure from CZFD, and the restricting contamination was not present 
13 hours later, it could not be determined what the actual surface conditions were at the 
time of departure. However, surface contamination was not considered when calculating
the take-off weight of the occurrence flight.
1.7 Meteorological information
This accident involved critical surfaces of an aircraft that became contaminated with ice as a 
result of in-flight ice accretion on approach and further ice accretion on the ground. This ice 
accretion was a result of the weather conditions at the time. 
This section will focus on the forecast weather conditions, the actual conditions, and how 
the ice formed on the aircraft. 
 24 Transport Canada, Advisory Circular (AC) 700-011: Operations on Runways with Unpaved Surfaces, Issue 01 
(16 March 2012), section 8.2.
25 Avions de Transport Régional, ATR 42 Airplane Flight Manual, Revision no. 24 (July 2013), Chapter 07, 
section 03, p. 1. 

18 | TRANSPORTATION SAFETY BOARD OF CANADA
1.7.1 Forecast conditions
1.7.1.1 Flight planning
There are no recorded weather observations for CZFD, and no METARs26 or aerodrome
forecasts (TAFs)27 are issued for the airport. The nearest airport for which METARs and 
TAFs are issued is CYSF, 42 NM east of CZFD. However, personnel at CZFD are available to 
provide a general description of local weather conditions on request. 
Because there are no formal weather products for CZFD, pilots and dispatchers use the 
graphic area forecasts (GFAs)28 for the area, as well as the METAR and TAF for CYSF, in
planning flights to CZFD.
At 1330, after the flight crew of WEW282 arrived for their flight and approximately 1 hour 
before the flight’s scheduled departure time from CYXE, a company dispatcher briefed the 
flight crew on the weather conditions for the route. 
The briefing included information about the conditions at CZFD, as observed by local 
personnel, and a review of the GFA for northern Saskatchewan, including the clouds and 
weather chart, and the icing, turbulence, and freezing level chart.
The crew were given a printed weather package, which included copies of the GFAs, 
METARs, and TAFs for the intended route of the flight. At the time of the briefing, there 
were no recent pilot weather reports29 and no significant meteorological information
(SIGMET)30 or aviation weather advisories (AIRMET).
31
 26 “An aerodrome routine meteorological report (METAR) describes the actual weather conditions at a specified
location and at a specified time as observed from the ground. METAR observations are normally taken and 
disseminated on the hour.” (Source: Transport Canada, TP 14371E [2017-2], Transport Canada Aeronautical 
Information Manual [TC AIM], MET – Meteorology [12 October 2017], section 8.1.)
27 “TAF is the international meteorological code for an aerodrome forecast, which is a description of the most 
probable weather conditions expected at an aerodrome, together with their most probable time of 
occurrence. It is designed to meet the pre-flight and in-flight requirements of flight operations.” (Source: 
Ibid., section 7.2.)
28 “The graphic area forecast (GFA) consists of a series of temporally adjusted weather charts, each depicting 
the most probable meteorological conditions expected to occur at or below 24 000 feet over a given area at 
a specified time. The GFA is primarily designed to meet general aviation and regional airline requirements for 
pre-flight planning in Canada.” (Source: Ibid., section 4.1.)
29 “A pilot weather report (PIREP) is a report pertaining to current weather conditions encountered by aircraft in 
flight. A PIREP is extremely useful to other pilots, forecasters, dispatchers and weather briefers as it provides 
up-to-the-minute weather information to supplement what is received from meteorological observing 
stations.” (Source: Ibid., section 2.1.)
30 “Information message issued by a meteorological watch office (MWO) to advise pilots of the occurrence or 
expected occurrence of specified weather phenomena, which may affect the safety of aircraft operations, and 
the development of those phenomena in time and space.” (Source: Ibid., section 6.1.)
31 “An information message issued by a meteorological watch office (MWO) to advise pilots of the occurrence 
or expected occurrence of weather phenomena, which may affect the safety of aircraft operations and which  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 19
1.7.1.2 Aerodrome forecasts
The most recent TAF32 for CYSF available at the time of briefing had been issued at 1143. 
The forecast was based on automatic observations and predicted that, at the time of 
WEW282’s arrival at CZFD, the conditions at CYSF would be
• variable winds at 3 knots,
• visibility greater than 6 SM,
• no precipitation, and
• overcast ceiling at 1500 feet AGL.
The forecast also predicted a temporary change in weather between 1200 and 2400, for an 
hour or less, that involved a decrease to 4 SM visibility in light snow and mist, and an 
overcast ceiling at 700 feet AGL.
This aerodrome forecast was updated throughout the day, and the most recent forecast 
available at the time of WEW282’s departure from CZFD had been issued at 1739. This 
forecast predicted the conditions would be 
• winds from 280°T at 5 knots,
• visibility greater than 6 SM in light snow,
• scattered clouds at 1000 feet AGL, and 
• an overcast ceiling at 2000 feet AGL. 
The forecast also predicted a temporary change in weather between 1800 and 0600, for an 
hour or less, that involved a decrease to 2 SM visibility in light snow and mist, scattered 
cloud at 700 feet AGL, and an overcast ceiling at 1000 feet AGL.
The guidelines for reporting TAFs in Canada are found in the Manual of Standards and 
Procedures for Aviation Forecasts.
33 In the manual, the only provisions for the forecast of 
icing in a TAF is freezing rain (FZRA), freezing drizzle (FZDZ), or freezing fog (FZFG). Fog 
and FZFG is to be forecast only if visibility is expected to be below ⅝ SM. There is no 
provision for forecasting freezing mist (FZBR) for conditions in which icing is expected to 
occur on surfaces, with visibility of ⅝ SM or greater, in the absence of precipitation.
Similar guidance is found in the International Civil Aviation Organization’s (ICAO’s) Manual 
of Aeronautical Meteorological Practice34 and the U.S. Federal Aviation Administration (FAA)
 
were not already included in the graphic area forecast (GFA). The message describes potentially hazardous 
weather conditions up to and including 24 000 ft (FL 240).” (Source: Ibid., section 5.1.)
32 Aerodrome forecasts have various validity periods and can be valid for up to 30 hours.
33 Environment Canada, Manual of Standards and Procedures for Aviation Forecasts (MANAIR), 7th Edition, 
Amendment 1 (April 2015).
34 International Civil Aviation Organization (ICAO), document no. 8896, Manual of Aeronautical Meteorological 
Practice, 12th Edition (2019). 

20 | TRANSPORTATION SAFETY BOARD OF CANADA
Advisory Circular (AC) 00-45H.
35 The FAA circular specifically states, “FZBR is not a valid 
significant weather combination and will not be used in TAFs.”
1.7.1.3 Graphic area forecasts
GFAs are issued 4 times daily, with a validity period of 12 hours. Each issue is a collection of 
6 charts: 2 charts valid at the beginning of the forecast period, 2 charts valid 6 hours into 
the forecast period, and the final 2 charts valid 12 hours into the forecast period. Each 
specified time has a chart depicting clouds and weather conditions, and a second chart 
depicting icing, turbulence, and freezing level conditions. 
The most recent GFAs for the Prairies region at the time of briefing had been issued at 
approximately 1130 and were valid for 1200 and 1800. The information in the GFAs
relevant to CZFD is provided in Table 4.
Table 4. Information from the graphic area forecast for the Fond-du-Lac Airport area issued at 1131 on 
13 December 2017
Valid 
time Clouds and weather Icing, turbulence, and freezing level
1200
Overcast clouds based at 2000 to 3000 feet above 
sea level (ASL), topped at 8000 feet ASL, and 
visibility more than 6 SM
Moderate mixed icing in clouds based at 
2000 to 3000 feet ASL and topped at 
8000 feet ASL
Patchy areas of visibility 4 SM to greater than 6 SM
in light snow and mist, ceilings between 800 to 
1500 feet AGL
Moderate mixed icing in clouds based at 
2000 to 3000 feet ASL and topped at 
8000 feet ASL
1800
Broken layer of clouds based at 2000 to 3000 feet 
ASL, topped at 7000 feet ASL; visibility more than 6 
SM
Patchy areas of moderate rime icing in 
clouds based at 2000 feet ASL and 
topped at 7000 feet ASL
Patchy areas of visibility 3 to 6 SM in light snow;
ceilings between 600 and 1200 feet AGL
Local areas of moderate mixed icing 
from the surface to 2000 feet ASL due to 
local freezing drizzle
The GFA did not predict any icing outside of clouds or precipitation, such as FZFG.
The next GFA was issued at 1731 (clouds and weather) and 1732 (icing, turbulence, and 
freezing level) and forecast similar conditions for the CZFD area at 1800; however, the crew 
did not receive this new chart before their departure at 1812.
1.7.2 Actual conditions
1.7.2.1 Stony Rapids Airport aerodrome routine meteorological reports
At the time of initial briefing, the latest METAR for CYSF had been issued at 1300 and 
indicated calm winds, visibility 9 SM in light snow, an overcast ceiling at 900 feet AGL, 
temperature −11 °C, dew point −12 °C, and an altimeter setting of 30.00 inHg.
 35 Federal Aviation Administration (FAA), Advisory Circular (AC) 00-45H: Aviation Weather Services
(14 November 2016), at https://www.faa.gov/documentlibrary/media/advisory_circular/ac_00-45h.pdf (last 
accessed 03 September 2020). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 21
Conditions at CYSF stayed relatively consistent throughout the day. The winds remained 
light; however, the ceiling tended to rise toward 2000 feet AGL, and the visibility varied 
between 9 SM and 2 SM in light snow and occasionally mist.
While on descent into CZFD, the flight crew received the latest CYSF weather, which 
recorded the conditions at 1654 as winds from 260°T at 3 knots, visibility 2½ SM in light 
snow, a few clouds at 1400 feet AGL with a broken ceiling at 2300 feet AGL and an overcast 
layer at 3700 feet AGL, temperature −10 °C, dew point −10 °C, and an altimeter setting of 
30.00 inHg. The crew also used this weather report for CYSF during preparation for 
departure out of CZFD.
Between 1654 and WEW282’s taxi for departure from CZFD at 1807, there were 13 updates 
to the weather at CYSF. By 1722, the automatic system at CYSF started to record icing (ICG)
on its ground-based sensor, and it reported icing in each of the 7 updates between 1722 and 
1800.
The 1800 METAR for CYSF recorded the conditions as winds from 270°T at 4 knots, 
visibility 9 SM with no precipitation, an overcast ceiling of 1900 feet AGL, temperature 
−10 °C, dew point −10 °C, an altimeter setting of 30.06 inHg, with a remark of icing during 
the past hour.
The conditions at CZFD at the time of departure were determined to be similar to those at 
CYSF, although visibility was uncertain, and ceilings were slightly lower, at around 1000 to 
1500 feet AGL.
Guidelines for the reporting of METAR weather observations in Canada are found in the 
Manual of Surface Weather Observation Standards (MANOBS). Observations at some 
locations, such as CYSF, are taken by an AWOS, and these METARs are annotated with 
“AUTO.”
There are a few differences between AUTO stations and those with human observers. AUTO 
stations do not report drizzle (DZ) or FZDZ, but rather will normally report these conditions 
as rain (RA), FZRA, or freezing – unknown precipitation (FZUP).
If icing occurs that does not involve precipitation or fog, METARs produced by human 
observers report this icing in the remarks section at the end of the METAR.
36 In contrast, 
AUTO METARs report icing (ICG) in the remarks37 section, regardless of the source of the 
icing.
There is no provision in MANOBS for METARs (whether AUTO or human-observed) to 
report FZBR, similar to TAF reporting. 
 36 Environment Canada, Manual of Surface Weather Observation Standards (MANOBS), 8th Edition (February 
2019), paragraph 6.6.2.4, p. 6-34.
37 Transport Canada, TP 14371E (2017-2), Transport Canada Aeronautical Information Manual (TC AIM), MET –
Meteorology (12 October 2017), section 8.5.4, Table 8.3. 

22 | TRANSPORTATION SAFETY BOARD OF CANADA
The icing recorded by the CYSF AWOS at the time of WEW282’s ground stop at CZFD 
coincided with the presence of light snow; however, a review of reports from earlier in the 
day showed that icing was occasionally recorded during mist conditions, in the absence of 
fog or precipitation, therefore indicating FZBR was occurring. 
1.7.2.2 Fort Smith Airport aerodrome routine meteorological report
The nearest METAR to CZFD based on human observations is from the Fort Smith Airport 
(CYSM), Northwest Territories, located 151 NM west of CZFD. From 1500 to 1700, the CYSM 
METAR reported the presence of light freezing drizzle. From 1719 to 2110, CYSM was 
reporting light snow.
1.7.2.3 Flight crew observations
On the day of the occurrence, 2 other flights (WEW660 and TW280) were also being 
operated to and from CZFD. 
WEW660 was operating all day in the Lake Athabasca region and mine sites; it arrived at
CZFD from CYSF approximately 12 minutes before WEW282. Because of the short distance 
between CYSF and CZFD, WEW660 maintained an altitude of 4000 feet, which put the 
aircraft between 2 layers of cloud. 
On descent into CZFD, WEW660 picked up a trace of icing, which the crew was able to shed 
before landing at CZFD. The crew reported that there was no precipitation between when
they established visual contact with the runway while on approach and when they departed
from CZFD. The aircraft was on the ground for approximately 15 minutes and did not de-ice 
while there.
TW280, was a scheduled flight from CYXE operating the same route as WEW282. TW280 
was also inbound to CZFD from the south and was approximately 6 minutes ahead of 
WEW282. 
The crew of TW280 reported a significant amount of icing, which accumulated quickly on 
the descent from its cruise altitude of 20 000 feet. The crew expedited the descent to 
minimize exposure to the icing conditions and reported that the worst of the icing was in 
the latter part of the descent, while below 10 000 feet. After the crew established visual 
contact with the runway, the aircraft did not encounter any precipitation on approach.
After landing at CZFD, the crew determined that the aircraft’s de-icing systems were 
effective at keeping ice off the critical surfaces, although some ice remained on unprotected 
surfaces. The aircraft was not de-iced while on the ground at CZFD and departed after 
approximately 35 minutes.
WEW282 encountered icing conditions for approximately 8 minutes between 8100 feet and 
2900 feet while on descent and approach. The crew of WEW282 did not observe
precipitation between when they established visual contact on approach and when the 
flight departed. The aircraft was on the ground for approximately 48 minutes. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 23
1.7.3 Aircraft icing conditions
1.7.3.1 General
Atmospheric conditions can lead to the formation of ice on the leading-edge surfaces of an 
aircraft when in flight and on the whole aircraft when it is on the ground. These conditions 
are referred to as “atmospheric icing conditions” or “aircraft icing conditions.”
1.7.3.2 Hazards of icing
The hazards of aircraft icing are well known to the flying community; however, the fact that
small amounts of ice on an aircraft can have a detrimental effect is often misunderstood and 
underestimated. 
TC’s Guidelines for Aircraft Ground Icing Operations state the following:
A very small amount of roughness, in thickness as low as 0.40 mm (1/64 in.), caused 
by ice, snow or frost, disrupts the air flow over the lift and control surfaces of an 
aircraft. The consequence of this roughness is severe lift loss, increased drag and 
impaired manoeuvrability, particularly during the take off and initial climb phases 
of flight. Ice can also interfere with the movement of control surfaces or add 
significantly to aircraft weight. There is no such thing as an insignificant amount of 
ice.38
Aircraft manufacturers take the hazard of icing into consideration when designing an 
aircraft and its lifting and control surfaces. ATR’s Cold Weather Operations brochure states: 
In order to ensure a satisfactory behaviour, aircraft are carefully designed so that 
stall will occur initially at the inner portion of the wing and spread toward the tip as 
angle of attack increases. Roll moments and abruptness of lift drop are then 
minimised.
This stall behaviour can be completely jeopardized by ice accretions that have no 
particular reason to be symmetrical or regular along the entire span of the wing.39
1.7.3.3 In-flight icing
Ice can form on aircraft in flight, mainly as a result of 3 processes: supercooled water 
droplets, freezing of liquid water, or the transition of vapour directly to ice. Depending on 
the process involved and the conditions, these accretions are normally classified into 
4 categories: clear ice, rime ice, mixed ice, and hoarfrost. All of these types degrade 
performance, although to varying degrees.
All aircraft are affected negatively when accumulating ice in flight. However, many aircraft 
types are certified for flight in icing conditions and are equipped with systems to shed the 
ice or prevent it from forming on the aircraft’s critical surfaces when in flight. 
 38 Transport Canada, TP 14052E, Guidelines for Aircraft Ground Icing Operations, Second Edition (April 2005), 
section 1.3, p. 15. 
39 Avions de Transport Régional – ATR Customer Services, Cold Weather Operations: Be Prepared for Icing
[brochure] (March 2011), Chapter E, subsection E.1.4. 

24 | TRANSPORTATION SAFETY BOARD OF CANADA
Aircraft anti-icing systems are designed to prevent accumulation, and de-icing systems, to 
remove it. These systems are designed in general for in-flight icing, and, as a result, protect 
only the leading edges of the control surfaces where ice normally begins to adhere. 
As a result of this incomplete coverage and normal limitations of the de-icing system, any 
ice that accumulates on areas outside of the protected areas, or ice that is not entirely shed 
by the de-icing system, will remain on the aircraft following an icing encounter unless 
removed by airflow, vibration, contact with warmer or drier air, or ground de-icing
equipment. 
The FCOM describes the hazard of this residual ice.
Even with airframe de-icers used according to procedure (i.e. as soon as and as long 
as ice accretion develops on airframe), the leading edges cannot be completely 
cleared of ice accretion because of existence of “unprotected” elements on the 
leading edges and continued accretion between two consecutive boots [sic] cycles.
This residual ice on leading edges changes noticeably the characteristics of flight 
BELOW the minimum operating speeds defined for ice accretion, as follows:
– Control effectiveness remains good, but forces to manoeuver in roll and to a lesser 
degree in pitch, may increase somewhat.
– Above the reduced angle of attack:
• An aerodynamic buffeting maybe [sic] felt which will increase with the 
amount of ice accumulated and angle of attack increase. 
• Stability may be slightly affected in roll, but stick pusher should prevent 
angle of attack increase before wing rocking tend [sic] to develop [...]
40
1.7.3.4 Ground icing
1.7.3.4.1 Ground icing in the absence of precipitation
Most commonly, ground icing occurs as a result of freezing precipitation, such as freezing 
rain, freezing drizzle, or snow. However, ground icing can also occur in the absence of 
visible precipitation. Moisture in the air in liquid form (water droplets) or gaseous form 
(water vapour) can transition into ice or frost on contact with any aircraft surface that is 
below freezing temperature (0 °C).
Ice and frost affect aircraft performance by disrupting airflow around the critical surfaces,
thereby reducing lift, increasing drag, and increasing the stall speed of the aircraft. No 
aircraft is certified or approved to depart with frost, ice, or snow adhering to its critical 
surfaces, with the sole exception of a small amount of frost on cold-soaked fuel tanks on 
specified aircraft.41
 40 Avions de Transport Régional, ATR 42 Flight Crew Operating Manual, Revision no. 41 (August 2015), Part 2, 
Chapter 02, section 12, p. 3.
41 Transport Canada, SOR/96-433, Canadian Aviation Regulations, subsections 602.11(2) and (3). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 25
1.7.3.4.2 Terminology related to ground icing
The underlying source of the ground icing phenomenon can be very complex. The following 
description has been simplified to aid general understanding, but is by no means a complete
technical presentation of the subject.
Frost or ice formation without visible precipitation generally requires that the water 
vapour42 in the air be near saturation conditions. An abbreviated description of the relevant 
concepts follows.
Water vapour pressure
Air is a mixture of nitrogen, oxygen, water vapour, and other trace gases. Water vapour 
pressure is a measure of the amount of water vapour in the air (“humidity”). It is typically 
less than 1% of the total air pressure.
43
Saturation
There is a theoretical limit to the amount of water vapour in the air at any given 
temperature. At this limit, the water vapour is saturated.
44 The saturation limits differ 
depending on whether one is considering transition into liquid water or into ice.
Condensation
When air is saturated with water vapour, condensation occurs.45 Condensation is the 
transition of gaseous water vapour into liquid water droplets or solid ice crystals.
46
Condensation from water vapour directly to ice is called deposition or sometimes 
desublimation; ice conversion directly to water vapour is called sublimation.
Nucleation
Condensation commonly occurs on object surfaces or around microscopic dust particles in 
the air. These non-gaseous surfaces, called nucleation sites,
47 provide the necessary 
molecular structure for water molecules to organize into liquid droplets or ice crystals.
 42 It is important to distinguish between water vapour, which is the gas state, and tiny liquid water droplets 
suspended in the air.
43 For example, air at standard sea level conditions of 101.325 kPa and 15 °C might have a vapour pressure of 
1 kPa.
44 Saturation corresponds to a relative humidity of 100%.
45 In practice, water droplets do not form exactly at the saturation limit. There is some random variation 
(stochastic process), and it is typical for water vapour to become oversaturated by 1% to 2% before water 
droplets appear.
46 Oxford University Press, Encyclopedia of Climate and Weather, Second Edition (2011), p. 277.
47 Condensation onto a surface is called heterogeneous nucleation. If, instead, it occurs within the vapour away 
from any surface, it is called homogeneous nucleation. 

26 | TRANSPORTATION SAFETY BOARD OF CANADA
Dew point
The saturation limit is lower at lower temperatures.48 If air containing under-saturated 
water vapour cools at a constant pressure and by a sufficient amount, the water vapour will 
become saturated and condensation will occur, either as mist droplets suspended in the air 
or as dew on surfaces. The temperature at which saturation occurs is the dew point. At high 
relative humidity, water vapour is close to the saturation limit; therefore, the air 
temperature is close to the dew point.
Supercooled liquid water
Water that remains liquid when cooled below 0 °C instead of transitioning to ice is called 
supercooled liquid water. It also can form when condensation occurs at dew points below 
0 °C.49 The temperature to which liquid water can be supercooled depends, in part, on the 
size of the droplets. Smaller droplets can persist as liquid at lower temperatures than larger 
ones before freezing.50 In the atmosphere, the first cloud droplets may not begin to freeze 
until −10 °C to −20 °C. The smallest droplets may remain liquid until almost −40 °C.51
Therefore, saturated atmospheric conditions below freezing can involve a combination of 
water vapour, supercooled liquid water droplets suspended in the air (as mist, fog, or 
cloud), and ice crystals suspended in the air.
Frost point
Similar to dew point, cooling air with under-saturated water vapour can reach the 
saturation limit with respect to ice. If conditions are suitable for ice-crystal nucleation, 
water vapour will condense as ice crystals (frost). This temperature is the frost point, which
is always higher than the dew point temperature, by approximately 10%. For example, an 
air mass with a dew point of −10 °C has a frost point of −8.9 °C.
The frost deposition rate depends on a number of factors, including the temperature 
difference between the surface and the air, and the amount of over-saturation (the “surplus” 
water vapour beyond the saturation limit).52
Latent heat
The condensation or freezing of water releases thermal energy, known as latent heat, into 
the surrounding air. This energy can affect the rate of freezing. Although it may slow the 
initial deposition of frost or ice, it will not prevent it. The thermal energy released from 
 48 Although, practically, this means that warm air can have more water vapour than cold air, this is purely a 
property of the water vapour itself, and not the air with which it is mixed.
49 Clouds are a common example of supercooled liquid water droplets.
50 This is due, in part, to the Kelvin effect, by which curved liquid surfaces of small radius have a much higher 
vapour pressure than flat liquid surfaces.
51 Freezing at such low temperatures is typically by homogeneous nucleation away from any foreign surface.
52 Transport Canada, TP 14145E, Laboratory Test Parameters for Frost Endurance Time Tests (December 2003). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 27
condensation will eventually diffuse away from the aircraft by convection53 and conduction 
within the air.
Mist or fog
The only distinction between mist and fog is the visibility level, as fog is denser. Both mist 
and fog are liquid water droplets suspended in the air that form as the result of 
condensation of saturated water vapour. If the temperature is below 0 °C, they are 
supercooled droplets. Mist droplets (about 0.02 mm diameter)54 are about 100 times 
smaller than rain drops, and individual droplets are generally not discernible to the naked 
eye.
55 Mist droplets are about 25 times smaller than drizzle, which has the smallest 
precipitation drops that fall by gravity.
1.7.3.4.3 The cooling process
As an air mass that contains water vapour cools, whether the water vapour transitions to 
liquid water, supercooled liquid water, or ice depends on the vapour pressure and the 
temperature (Figure 5).
Figure 5. Graph showing the relationship between water vapour pressure and temperature 
(Source: TSB)
At temperatures above 0 °C, the saturation curve (line labelled vapour pressure over water 
in Figure 5) represents the transition boundary between water vapour and liquid water, 
 53 The air cooling occurs more effectively if winds are light, which aids frost formation. (Source: Transport 
Canada, TP 14145E, Laboratory Test Parameters for Frost Endurance Time Tests [December 2003]).
54 By volume, this is one-millionth the size of an average raindrop.
55 Light mist at −10 °C may not be perceptible in dark nighttime conditions with limited ambient lighting. 

28 | TRANSPORTATION SAFETY BOARD OF CANADA
with water vapour below the curve. The closer the temperature is to the curve, the higher 
the relative humidity. Directly on the curve, the water vapour is saturated with respect to 
liquid water (100% relative humidity), and, above the curve, the water vapour condenses 
into liquid water droplets in the air (mist or fog) or on an object’s surface (dew).
Below 0 °C, there are 2 saturation curves to consider. The first, the ice-vapour saturation 
curve (line labelled vapour pressure over ice in Figure 5), represents the transition 
boundary between water vapour and ice. Below the curve, the water is vapour. On the 
curve, the water vapour is saturated with respect to ice. Above the curve, the water vapour 
condenses directly to ice (frost deposition), provided suitable nucleation sites are available 
for ice crystals to form.
For example, in Figure 5, consider air with water vapour at point A that cools (at constant 
vapour pressure) upon contacting a cold surface. When it meets the ice-vapour saturation 
curve at point B, the water vapour will transition to frost crystals. The temperature at 
point B is the frost point.
If suitable nucleation sites are not available, ice crystals cannot form. Water can remain in 
the air as vapour that is over-saturated with respect to ice. 
The second saturation curve below 0 °C is for supercooled liquid water (line labelled vapour 
pressure over supercooled water in Figure 5). At point C, the water vapour becomes 
saturated with respect to liquid water. This temperature is the dew point, below which the 
water vapour will condense into supercooled liquid water droplets (sub-zero mist).
Supercooled droplets will transition into ice as soon as suitable nucleation conditions are 
encountered. This can occur rapidly as clear ice forming on contact with any cool surface.56
If such supercooled mist droplets at point D encounter an aircraft surface, they will freeze 
instantly as clear ice.
1.7.3.4.4 Formation of frost versus clear ice
Because supercooled mist droplets will freeze on contact with a cool surface, water vapour 
close to saturation (high relative humidity) presents a high risk for ground icing at sub-zero 
air and surface temperatures.
If the air contacts a sub-zero surface that causes the air temperature to drop, the water 
vapour will be saturated and transition to ice crystals as frost.
If, instead, the air cools on its own, the water vapour will be over-saturated with respect to 
ice until the dew point is reached. Once the dew point is reached, the vapour will condense 
to supercooled liquid water droplets as mist. If these supercooled mist droplets then contact 
a cold surface, they will instantly transition to ice crystals as clear ice.
 56 This is essentially how in-flight icing occurs in clouds. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 29
1.7.3.4.5 Aircraft surface temperature
During WEW282’s flight from CYPA to CZFD, the aircraft climbed to FL220. During the 
flight, the aircraft was in air below −10 °C for about 1 hour 40 minutes, of which more than 
an hour was in air from −35 °C to −38 °C. The aircraft structure would have cooled during 
the flight in the colder air at altitude.
Aircraft surface temperature following landing depends mainly on the air temperature and 
time spent at altitude. Although an aircraft descends into generally warmer air at lower 
altitudes, surface temperature change takes time. Some surfaces can still be colder than the 
surrounding air after the aircraft has landed. In particular, cold-soaked fuel57 in the tanks 
can keep some surfaces colder than the ambient temperature.
On the ground, there can be significant temperature differences across aircraft surfaces and 
between surfaces and the surrounding air, and these can change over time. Freezing 
conditions can be encountered on some, all, or none of the aircraft’s surfaces at any given 
moment.
After the aircraft shuts down, surface temperatures will continue to change in a complex 
way. Both cold and warm surfaces tend to approach the surrounding air temperature. Heat 
sources such as engines, an auxiliary power unit, or warm fuel can cause local areas of the 
aircraft to remain warmer than the ambient temperature. Ambient wind or propwash can 
carry heat to or away from the aircraft. Changes in air temperature, wind conditions, 
precipitation, and cloud cover can all affect the local surface temperatures over time. 
Surfaces ultimately tend to settle at several degrees below the ambient temperature 
because of radiational cooling.58
Any spot on the aircraft with a sub-zero surface temperature is vulnerable to ice formation.
1.8 Aids to navigation
All aids to navigation were serviceable and had no effect on this occurrence. WEW282 was 
using RNAV navigation for the flight to and from CZFD.
 57 Fuel has a relatively high thermal inertia. It warms up or cools down much more slowly than aluminum 
aircraft structure.
58 All objects radiate infra-red energy (which can be observed with an infra-red camera). They can also absorb 
energy radiated from other objects. If these processes result in a net loss of energy, the object’s temperature 
will drop over time (if no other energy is added) and can therefore drop below the ambient air temperature. 
For example, an aircraft under a clear night sky emits more energy than it receives from the sky. Under such 
conditions, the aircraft surface temperature can drop several degrees below the ambient air temperature. 
This radiational cooling is a common event on Earth that helps produce fog, mist, frost, and ice. (Source: 
Transport Canada, TP 14052E, Guidelines for Aircraft Ground Icing Operations, Fifth Edition [August 2020], 
Chapter 12, paragraph 12.1.7.3.) 

30 | TRANSPORTATION SAFETY BOARD OF CANADA
1.9 Communications
CZFD is an uncontrolled airport located within uncontrolled airspace. The airport has an 
aerodrome traffic frequency (ATF) area with a radius of 5 NM that is centred on the airport 
and extends vertically up to and including 3900 feet ASL. The ATF is 123.2 MHz.
The crew of WEW282 made all the required ATF calls during their arrival at and departure 
from CZFD.
1.10 Aerodrome information
The Fond-du-Lac Airport (CZFD) is owned and operated by the Saskatchewan Ministry of 
Highways and Infrastructure. The airport is located approximately ½ km north of the Fond 
Du Lac Denesuline First Nation.
CZFD is available for use 24 hours a day, 7 days per week, supporting both day and night 
visual flight rules and instrument flight rules operations. The airport is normally 
unattended, and hours of operation are at the discretion of the local contractor, who carries 
out daily inspections and maintenance work at the airport for the Ministry. There is no de￾icing/anti-icing facility or service provider at CZFD, nor is such a facility or provider 
required by regulations. 
1.10.1 Runway 10/28
CZFD has a single runway, Runway 10/28, and at the time of the occurrence Runway 28 was 
in use. The take-off run, accelerate-stop distance, and landing distance available are all 3805 
feet, whereas the take-off distance available is 4297 feet, accounting for a 492-foot clearway 
at the end. The runway is 75 feet wide and has a treated gravel surface with an uphill slope 
of 0.43%.
Runway 10/28 at CZFD was reconstructed and sealed in 1999. Before the reconstruction,
the runway surface was straight gravel. The process involved spreading and packing gravel 
over the sub-base before applying the seal (consisting of liquid asphalt and aggregate) to 
the runway, followed by compaction using a rubber tire roller. After a setting period, the 
loose gravel was swept off and a second layer of seal was applied using the same process.
1.10.2 Treated gravel guidance
A treated gravel surface, sometimes called chip seal, differs from both gravel and paved 
surfaces. The surface consists of a firm base of gravel pavement structure, covered with a 
thin layer of asphalt-stabilized material that helps to keep the moisture out. A variety of 
asphalt emulsions and cover aggregate combinations can be used when applying a treated 
(seal) coat, resulting in a surface that can accommodate varying loads.
Since the treated surface is not bonded to the sub-surface, as asphalt is, TC does not 
consider the runway surface as paved, stating in its 2012 Advisory Circular (AC) 700-011, 
that 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 31
[s]eal coated runways may lack the surface bearing strength of paved hard surface 
runways, and in this respect are more characteristic of runways with unpaved 
surfaces.59
Since the most common cause of operational problems on unpaved runways is failure of the 
surface layer caused by shear under high tire pressure, a measurement of the surface shear 
strength of the runway surface, called the California bearing ratio (CBR), is often used to 
determine a tire pressure limit for a given runway surface. 
This ratio can be expressed as a percentage or as a whole number from 0 to 100. In the 
summer of 2009, Runway 10/28 at CZFD was measured and determined to have an average 
CBR value of 44.4. This measurement met the requirements in the ATR 42 AFM for inclusion 
of a penalty when calculating take-off performance; however, the 44.4 CBR summer 
measurement may not have been representative of the actual surface strength during the 
winter season at CZFD. 
1.11 Flight recorders
The occurrence aircraft was equipped with a flight data recorder (FDR) and cockpit voice 
recorder (CVR), both installed in racks in the empennage. The FDR and CVR were recovered 
from the aircraft wreckage in undamaged condition and examined at the TSB Engineering 
Laboratory in Ottawa, Ontario. The data from both recorders were successfully recovered.
The FDR contained more than 536 hours of flight data, including the entire occurrence flight 
and 502 previous flights. The CVR had recorded 2 hours 4 minutes of audio from 4 separate 
microphones, including recordings from the captain’s and FO’s microphones, a cockpit area 
microphone, and an extra channel.
Further flight data were recovered from the aircraft’s EGPWS, and 2 separate FMS units. 
Additionally, ground-based radar data were recovered from NAV CANADA.
1.11.1 Flight data analysis
The aircraft’s detailed flight path was reconstructed using information from the aircraft’s 
FDR, CVR, FMS, and EGPWS, as well as the ground radar data.
The aircraft’s FMS recorded highly accurate 3-dimensional geodetic position data; however,
it was recorded at a sampling rate of only 1 Hz. This sampling rate was sufficient to
represent the trajectory of non-dynamic flight, such as the flight from CYPA to CZFD, but 
insufficient for the dynamics of the trajectory during the occurrence flight. 
The FDR recorded longitudinal, lateral, and vertical accelerations relative to the aircraft 
body’s frame. By transforming these accelerations into the Earth’s frame of reference, and 
correcting for biases, an accurate flight path of the aircraft on departure was determined. 
 59 Transport Canada, Advisory Circular (AC) 700-011: Operations on Runways with Unpaved Surfaces, Issue 01 
(16 March 2012), subsection 3.0(5). 

32 | TRANSPORTATION SAFETY BOARD OF CANADA
While reconstructing the flight path was relatively straightforward, accurately assessing the 
aircraft’s drag and lift performance, the performance of the roll control system, and the 
actuation of stall protection were significantly more complicated. 
1.11.1.1 Drag and lift performance
1.11.1.1.1 Background
Ice contamination, even in seemingly small amounts, can lead to significant aerodynamic 
penalties, primarily related to drag and lift.
Drag and lift penalties are mutually dependent: a degradation in lift performance causes a 
degradation in drag performance. For example, in a scenario where an ice-contaminated 
aircraft is attempting to maintain a desired airspeed, the ice contamination will deteriorate 
the lift-performance of the wing, requiring a higher AOA to generate the necessary lift. The 
higher AOA will, in turn, generate higher induced drag. As a result of this increase in 
induced drag, in combination with the parasite drag from the contaminated surfaces, the 
required power to maintain the desired airspeed will increase. 
To understand how the ice contamination affected the aircraft’s performance during the 
approach to and departure from CZFD, the investigation included a handling quality 
analysis to measure the aircraft drag and lift characteristics, using data from the aircraft’s 
FDR.
1.11.1.1.2 Methodology
The analysis was done collaboratively by the TSB, the Bureau d’Enquêtes et d’Analyses pour 
la sécurité de l’aviation civile of France (the BEA), and ATR to compare the expected and 
actual total forces and moments in order to identify the presence and effect of 
contamination on both the approach to and departure from CZFD. The analysis was carried 
out using an advanced desktop simulator60 and the aerodynamic characteristics of the 
ATR 42-320 aircraft. 
First, the engine and control inputs were analyzed to output the aircraft’s expected total 
forces and moments, assuming an uncontaminated aircraft. Second, the aircraft’s recorded 
accelerations and attitudes were analyzed to output the aircraft’s actual forces and 
moments. Third, the differences between the expected and actual forces and moments were 
analyzed to identify the effect of contamination. 
1.11.1.1.3 Approach phase
The APM’s DEG PERF alert is triggered by design when the 60-second average drag 
increases beyond 28% higher than the reference model for a clean aircraft. During the 
descent to CZFD, drag progressively increased and the DEG PERF alert triggered. The point 
in time when the simulation indicated a 28% drag increase coincided with the point in time 
when the FDR on the occurrence flight recorded the DEG PERF discrete parameter.
 60 Outil de Simulation des Mouvements Avion (OSMA) desktop simulator, developed by Airbus. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 33
The analysis determined that lift performance was degrading, and reached a 10% 
degradation at a similar time.
1.11.1.1.4 Ice detected
The FDR records an “icing detected” discrete parameter showing the status of the ice 
detection probe. This probe, located under the left wing, alerts the crew as soon as and as 
long as it senses ice accretion. 
When the probe accretes more than 0.5 mm of ice, it initiates a 7-second probe heating cycle 
in order to shed the ice and illuminates an ICING light in the cockpit for at least 60 seconds.
The time between heating cycles is an indication of the rate at which the aircraft is accreting 
ice. The first heating cycle and ICING light while on descent into CZFD commenced when the 
aircraft was at 7600 feet ASL. The second heating cycle occurred only 46 seconds later, and 
the time interval between subsequent heating cycles became progressively longer. 
Therefore, the rate of ice accretion was greatest at 7600 feet ASL and progressively reduced 
until ice accretion was no longer detected at 2900 feet ASL.
The airframe de-icing system remained on for 1 minute 54 seconds after the ICING light was 
extinguished for the final time. This permitted the system to cycle the wing boots twice after 
ice accretion had stopped.
1.11.1.1.5 Occurrence departure
The drag and lift performance on departure from CZFD were analyzed using the same 
method as that for the approach; however, it was recognized that the results were
considered accurate only once the aircraft had exited the influences of ground effect. 
It was determined that the aerodynamic characteristics during the departure deviated from 
their references by even greater amounts than those on approach. The analysis showed that 
drag increased by as much 58% and lift performance degraded by as much as 25% during 
the occurrence departure.
1.11.1.2 Roll control system performance
1.11.1.2.1 Background
The ATR 42 roll control system uses ailerons and spoilers to control the roll attitude of the 
aircraft.
The dynamic roll attitude of an aircraft is influenced by many factors, including the roll 
moment due to deflection of the control surfaces (referred to as roll control derivative), and 
the opposing roll moment due to the roll rate (referred to as roll damping).
The roll control derivative is a metric for evaluating an aircraft’s roll control performance. It 
defines the non-dimensional contribution to the rolling moment for a given deflection angle
of the control surfaces, or, to put it more generally, the effectiveness of the ailerons and 
spoilers. Normally, this control derivative is a constant characteristic of the airframe.  

34 | TRANSPORTATION SAFETY BOARD OF CANADA
However, if these control surfaces are contaminated, the aircraft’s roll control derivative 
may diminish.
Roll damping occurs during a roll and results from the down-going wing producing more lift 
than the up-going wing as a result of its increased AOA. This increased lift opposes the 
rolling motion and reduces or dampens the rate of roll.
When an aircraft is at or near the stall, and a roll is induced, the roll dampening that is 
normally present is greatly reduced. This reduced roll dampening occurs because the local 
span-wise AOA on the descending wing is high enough to cause local separation of the air 
flow over the wing and, as a result, the lift increase that normally occurs on the down-going 
wing (the roll dampening) is comparatively less. This changes the dynamic handling 
qualities of the aircraft and can lead to unexpected aircraft response to control inputs.
1.11.1.2.2 Comparison with previous flights
To assess the aircraft’s roll control performance on departure, the data from the occurrence 
flight was compared with that from the more than 500 flights recorded on the FDR. This 
comparison showed that, during the departure, the roll control derivative, or the 
effectiveness of the ailerons/spoilers, was reduced when compared with the average.
Because many variables can affect the calculation of the roll control derivative, this 
comparison could not determine the exact magnitude of the degradation.
1.11.1.2.3 Computer simulation
The computer simulation was used to analyze the roll performance. First, the simulation 
generated the expected rolling moment coefficient, based on aircraft control inputs; second, 
it generated the actual rolling moment coefficients based on the recorded angular rates. The 
results of the expected and actual coefficients were then compared. It was observed that a 
difference between the actual coefficients of lift on the left and right wings occurred without 
any roll control inputs, indicating that there was an asymmetry in the distribution of lift. 
Shortly after the introduction of this asymmetry of lift, the ailerons were deflected in an 
attempt to counteract the asymmetry. 
While this method was unable to directly evaluate the roll control derivative, the results 
indicate that the effectiveness of the ailerons was not significantly degraded and had 
sufficient control authority to overcome the asymmetry in the lift distribution. Since the 
ailerons maintained sufficient effectiveness to counteract the roll, it was determined that 
the roll oscillations were not the result of lost aileron effectiveness.
1.11.1.3 Stall warning 
The stall warning on the ATR 42 consists of an aural alert, called the stall warning cricket, a 
stick shaker, and a stick pusher. 
The stick shaker and cricket operate using the same logic and operate simultaneously in all 
cases. For a flap setting of 15°, as was set for departure from CZFD, the stick shaker and the 
cricket should occur at an AOA vane angle of 18.1° and the stick pusher should activate at an  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 35
AOA vane angle of 23.60° and deactivate at 20.10°. The stick pusher is inhibited for 
10 seconds after takeoff or if the left and right AOA disagree by more than 4°.
The audible stall warning cricket was captured on the CVR during the airborne portion of 
the occurrence flight, after rotation and before initial impact. However, the sound from the 
stick shaker could not be conclusively identified, and, therefore, it could not be determined 
whether it activated. 
During the occurrence departure, there were 2 instances of high AOA that exceeded the 
stick pusher threshold. At 1812:39.0, during the first instance of high AOA, although the 
stick pusher angle threshold was exceeded, operation of the stick pusher was inhibited 
because the aircraft was still within 10 seconds of weight-off-wheels. 
At 1812:46.5, during the second instance of high AOA vane angle, the conditions were met 
for the stick pusher to activate. However, at that point, the aircraft was in a steep left bank 
and was beginning to collide with trees. It is possible that the unrecorded left AOA sensor 
differed from the right AOA sensor by more than 4°.
During the second instance of high AOA, when the stick pusher may have activated, flight 
data showed that the elevator was moved to a trailing-edge up position. This movement is 
not consistent with stick-pusher activation, but rather indicates that the elevator movement
was a direct result of crew input or from the collision sequence.
1.12 Wreckage and impact information
1.12.1 Occurrence site
The aircraft took off from Runway 28, which has a runway heading of 284° magnetic or 
296°T. Immediately following takeoff, the aircraft began to deviate to the left, passed over a
road near the airport perimeter fence, and then proceeded toward a wooded area. 
The terrain in the wooded area rises slightly, and the aircraft struck treetops in this area
before contacting the ground near the top of the hill. As it made initial contact with the 
ground and then a secondary ridge, the aircraft left a debris trail before coming to rest. In 
relation to the departure end of the runway, the aircraft’s final resting position was 600 m
away, on a bearing of 270°T (Figure 6). 

36 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 6. Aerial view of occurrence site (Source: Royal Canadian Mounted Police, with TSB annotations)
1.12.1.1 Wreckage path
The occurrence aircraft initially struck the trees approximately 430 m west-northwest of 
the runway. The pattern of breakage in the treetops coincided with a left bank angle of 
approximately 45° (Figure 7). 
Figure 7. Photo of initial impact with trees (image facing towards the airport and showing the aircraft’s 
bank angle at the time of impact) (Source: TSB)
The aircraft made initial ground contact about 20 m following these tree strikes, on a track 
of approximately 258°T, which matched the track through the trees. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 37
Following initial ground contact, there was secondary contact, and, approximately 70 m 
following the initial contact, the aircraft went over a ridge before sliding down a hill for a 
further 90 m. 
The hill sloped down approximately 6.95° (12.11%) to the final resting position of the 
aircraft. While the aircraft was sliding, it rotated or yawed to its left. By the time it came to a 
rest, the longitudinal axis of its fuselage was almost perpendicular to the direction of travel
(Figure 8).
Most of the debris was contained on the downward slope after the ridge in an area of
broken trees. The path following the ridge was on a track of 247°T; 11° to the left of the 
aircraft’s track before the ridge.
Figure 8. Photo showing the path of the aircraft’s slide over the ridge (Source: TSB)
1.12.2 Aircraft wreckage
1.12.2.1 General
The aircraft came to rest rolled to its right side, with the right wing touching the ground and 
the left wing tipped upward (Figure 9). While the left wing tip was missing, the remainder 
of the wing did not fracture or bend. Both engines were still securely attached to the wings.
The bottom left of the nose section of the aircraft fuselage was crushed by the impact, 
although the crushing was localized just underneath the cockpit.
The fuselage had a partial, but nearly complete, transverse fracture just forward of the wing 
and between the 4th and 5th windows. The fracture resulted in a V-shape opening of the  

38 | TRANSPORTATION SAFETY BOARD OF CANADA
fuselage to the exterior environment. This transverse fracture resulted in the forward part 
of the fuselage partially separating from the main section of the fuselage. 
Without restrictions from the wings, the forward section of the fuselage rolled
approximately 90° to the right, and the remaining aft section of the fuselage rolled 
approximately 40° to the right, with the wing structure restricting further rotation.
The main wing structure above the centre fuselage section had collapsed downward, and 
some of the fuel contained in the wing had leaked into this section. The main landing gear 
housing structure, at the bottom of this area, was also displaced upward as a result of the 
impact. 
Figure 9. Photo of aircraft wreckage, as seen from above (Source: Royal Canadian Mounted Police, with 
TSB annotations)
1.12.2.2 Centre fuselage
During the initial on-site examination, significant damage was observed to the centre 
fuselage section, underneath the wing, which had collapsed during the impact.
The main wing structure was significantly displaced downward, and the forward bulkhead 
of the main landing gear housing structure was pushed upward. As a result, part of the cabin 
floor in this area was displaced well above the cabin window (Figure 10). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 39
Figure 10. Close-up view of the fractured fuselage forward of the wing (Source: Royal Canadian 
Mounted Police, with TSB annotations)
Examination of the upper portion of this centre fuselage section underneath the wing 
showed that the 2 strongest circular frames (frames 25 and 27), also called lift frames, had 
fractured. Since these lift frames support the wing and maintain the circular integrity of the 
cabin, these fractures had resulted in the collapse of this fuselage section. 
For each frame, the fracture was approximately level with the bottom of the cabin windows, 
which is consistent with the vertical centre of the frames. The radius of each fractured 
frame was calculated to be approximately 128 cm, almost the entire original radius of the 
frame, which was 135 cm. This indicates that the lift frames had limited deformation before 
being fractured.
The lower portion of the centre fuselage section, which was built with partial bulkheads on 
frames 25 and 27, included a keel beam and the main landing gear box structure. There was 
no sign of vertical crushing on either bulkhead, although they fractured at their 
approximate centres. This absence of deformation indicates that this structure was too rigid 
to absorb the impact energy in the vertical direction.
1.12.2.3 Forward and aft fuselage
At the time of the initial on-site examination, the aft fuselage section was twisted clockwise 
(if viewed from rear) relative to the centre fuselage, and the twisting and rolling of this 
section to its right side exposed the bottom of this fuselage section. There was no evidence
of significant crushing damage to the bottom of this aft fuselage section (Figure 11). 

40 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 11. Left side view of the lower centre and aft fuselage sections of the aircraft at the crash site
(Source: TSB)
Later off-site examination of the forward fuselage section, just aft of the cockpit, showed 
that the left bottom area of the fuselage and the stanchions underneath the floor were 
crushed to some extent. 
The fuselage above the floor in this area was hardly deformed by the impact, and 201 cm of 
the original 209 cm of interior height remained (Figure 12).  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 41
Figure 12. Cross-sectional view of the forward fuselage, just aft of the 
cockpit, looking forward, from later off-site examination (Source: TSB)
1.12.2.4 Cabin floor and seat tracks
The floor structure is an integrated part of the fuselage structure of the aircraft. The 
occurrence aircraft’s floor structure design uses the seat tracks as the longitudinal beams of 
the floor frame. Some other aircraft designs use a dedicated floor frame.
The difference between the 2 designs is that the former has the inertial load from seats 
(occupants) directly applied to the floor frame, whereas the latter has the inertial load from 
seats applied first to the seat tracks, then from the seat tracks to the floor panels, before 
being eventually transferred from the floor panels to the floor frames. In an accident
scenario, the load distribution on the floor frames can be expected to differ between these 
2 designs.
The cabin floor frame of the occurrence aircraft was constructed using transverse beams 
and seat tracks (Figure 13). There are 2 types of connection between a transverse beam and 
seat tracks, depending on whether a single piece of seat track passes over the transverse 
beam (type I) or if 2 seat tracks make an end-to-end connection at the transverse beam 
(type II). 

42 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 13. Diagram showing the floor structure with inset images showing examples of type I and 
type II joints (Source: TSB)
The floor structure, including the seat tracks, failed and buckled in several locations.
Examination found that, among all seat tracks examined, several type II joints had failed, 
whereas none of the type I joints had failed. The failure modes were either failure of the bolt 
or shear failure of the plate with the bolt holes on the upper cap of the transverse beam.
A longitudinal load on the seat tracks is induced when an inertial load is transmitted to the 
seat tracks. This can occur as a result of differential crushing deformation between different 
fuselage sections (due to differences in their rigidity) or as a result of deflection of the seat 
tracks (due to an inertial load in a vertical direction from the seat). 
In keeping with this, 2 fractured seat tracks extending from the floor on top of the lower 
portion of the centre fuselage section were bent downward, suggesting a differential 
crushing between the lower portion of the forward fuselage section and that of the centre 
fuselage section. 
The failure of the type II joints was consistent with tensile overstress due to transfer of 
longitudinal load from the seat track to the joint. No deformation was observed on the 
connecting ends of the seat tracks.
Given its smaller cross-sectional area for load transfer, the stresses experienced at the 
type II joint are higher than at a type I joint. This is because longitudinal tensile loads in the 
type II joint design must transfer through the upper cap, which is significantly thinner than
the track itself. As a result, the type II joint design is considered weaker than the type I 
design.
1.12.2.5 Passenger seats
The first 2 rows of seats on the left and the first row of seats on the right were not occupied 
by passengers and were not damaged in the occurrence. 
Seats from row 7 to row 11 at the rear of the passenger cabin were consistently deformed 
towards the right side of the aircraft; however, no sign of bending damage was observed on  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 43
the horizontal tubes of the seats. The damage to these seats was consistent with the damage 
caused by the inertial load from the occupants in a lateral direction.
The only seats that showed a different damage pattern were the 2 left-side seats in rows 5 
and 6 (Figure 14). On both of these seat pairs, the inboard legs had fractured, and the front 
outboard legs were deformed into a crossbow shape. This damage is consistent with an 
inertial load in a vertical (downward) direction from the occupants. 
The front horizontal tube of the seat frames had fractured at their lateral centre, which is 
consistent with bending failure caused by large inertial load in a vertical (downward) 
direction from the occupants.
Figure 14. Photo showing damage to the left-side seat pair from row 6 (Source: TSB)
1.12.2.6 Flight attendant seat
The cabin floor between the main entrance and emergency exit showed no sign of damage 
or deformation; however, the FA seat was missing and was found later, broken into pieces. 
The seat’s bottom mounting structure was found still fastened to the floor tracks. 
The FA seat was manufactured by SICMA Aero Seat of France (a part of Zodiac Aerospace of 
France at the time of the accident, now part of Safran). A key component of the FA seat is the 
structure assembly (Figure 15), a single-piece sandwich panel made of aluminum face
sheets and aluminum honeycomb. 

44 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 15. Diagram of flight attendant seat and assembly (left image) and photos from the occurrence 
seat showing the honeycombing (right image) (Source of diagram: Zodiac Seats France, Component 
Maintenance Manual with Illustrated Parts List – Cabin Crew Member Seat, Part Number 134-Series, 
Revision no. 13 [10 January 2017], with TSB annotations. Source of photos: TSB)
The structure assembly was found broken into pieces. Both the left and right legs had 
separated from the back panel and from their lower portions, which were still inserted into 
the slots of the lower fixing assembly.
Both left and right legs of the seat-structure assembly failed when their aluminum 
honeycomb core separated from the aluminum face sheets. The separated face sheets
showed no trace of adhesive, which is consistent with adhesive failure (i.e., failure at the 
interface between the face sheet and adhesive). 
There was evidence that extensive repairs had been made to these honeycomb panels on 
more than 1 occasion, as several drill holes of different diameters were identified, as were 
3 different adhesives types. 
Review of the service history and Component Maintenance Manual (CMM) for the FA seat 
indicated that the concerned FA seat had been repaired in 2014 by following a standard 
composite repair procedure for the ATR 42 aircraft. However, the ATR 42 structural repair 
manual does not cover the maintenance and repair of the seat structure. 
The shop that performed the last repair on the structural assembly of the FA seat is no 
longer in business. Because of this, no further information could be obtained as to why it 
selected a standard composite repair procedure not approved for the FA seat. 
The requirements for repair of the FA seat structure are detailed in the CMM from the seat 
manufacturer. While the general description of the seat uses the technical term “shaped 
honeycomb structure sandwich panel” for the seat-structure assembly, the CMM does not 
detail a repair procedure for such a structure assembly or for a honeycomb sandwich panel, 
nor does is it include the composite repair procedure found in the ATR 42 structural repair  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 45
manual. In contrast, the CMM states that “Metal components which have been damaged, 
must be replaced; they are considered “not repairable” [emphasis added].”61
Communication with the manufacturer of the FA seat (Zodiac Aerospace of France) 
confirmed that the structure assembly of the FA seat is considered not repairable and must 
be replaced when damage is detected.
To determine whether the unapproved repair to the FA seat of the ATR 42-320 aircraft in 
this occurrence was an isolated case, a reference FA seat from another West Wind aircraft 
(registration C-GWWC) was examined. The examination confirmed that the reference seat 
also had defects and unapproved repairs, effectively rendering it non-serviceable. The 
investigation did not determine when or by whom these unapproved repairs had been 
completed.
1.12.2.7 Engines and propellers
Examination of the engines and propellers on the aircraft following the accident determined 
that there were no abnormalities. 
The on-site inspection revealed that both engines had ingested wood, wood chips, and wood 
dust along the gas paths. This indicated that both engines were delivering power to the 
aircraft during its descent into the trees. Both propellers also showed clear indications of 
high-speed rotation. 
Subsequent analysis of recorded data confirmed that the engines were producing power as 
expected, and the propellers were performing as designed.
1.12.2.8 Flight controls
Flight controls were checked for proper attachment and continuity, and no defects were 
found in the aircraft. Trim tab positions were measured and recorded at the actuator and 
found to be in the proper position for takeoff. 
The horizontal stabilizers had leading-edge impact damage consistent with the aircraft 
descending through the trees; as a result of this impact, the elevator disconnect was found 
disconnected.
There were no recorded data that indicated any abnormalities with the flight controls or 
their operation. 
1.12.3 Remnants of ice contamination
1.12.3.1 TSB examination
TSB investigators arrived at the crash site 22 hours after the accident. 
 61 Zodiac Seats France, Component Maintenance Manual with Illustrated Parts List – Cabin Crew Member Seat, 
Part Number 134-Series, Revision no. 13 (10 January 2017), p. 6001. 

46 | TRANSPORTATION SAFETY BOARD OF CANADA
The right wing and control surfaces were the only parts of the aircraft where a tactile and 
close visual examination could be conducted. These surfaces were generally clear of 
contamination, except for about 1 cm of snow that had accumulated since the accident. This 
area of the wreckage experienced fuel leakage and substantial movement of people and 
equipment during the rescue operation, and it is almost certain this activity removed 
existing contaminants.
The left wing and empennage were photographed but were not accessible for tactile and 
close visual examination until 5 days after the accident. Precipitation during this period 
altered the condition of the surfaces, and it is impossible to precisely state the extent and 
severity of any contamination present during the occurrence flight based on this 
examination.
1.12.3.2 Earlier photographs of contamination
Examination of photographs taken by the Royal Canadian Mounted Police (RCMP) about 
8 hours after the accident revealed the presence of ice contamination on the aircraft
(figures 16, 17, and 18). Although ground icing conditions persisted following the crash, 
these figures provide some indication of the contamination present on the aircraft during 
the occurrence flight.
Figure 16. Photo of left horizontal stabilizer, with 2 inset images showing ice contamination on leading 
edge (Source: Royal Canadian Mounted Police, with TSB annotations) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 47
Figure 17. Photo of vertical stabilizer, with 2 inset images showing ice contamination on the leading edge 
of rudder horn and the right side of the stabilizer (Source: Royal Canadian Mounted Police, with TSB 
annotations)
Figure 18. Photo of inner left wing with inset image showing surface contamination on lower leading edge 
(Source: Royal Canadian Mounted Police, with TSB annotations)
1.13 Medical and pathological information
The investigation determined that there was nothing to indicate that the performance of the 
flight crew or the cabin crew was degraded by medical, pathological, or physiological 
factors. 

48 | TRANSPORTATION SAFETY BOARD OF CANADA
1.14 Fire
There was no pre- or post-impact fire.
1.15 Survival aspects
1.15.1 Crashworthiness
Crashworthiness is generally defined as the ability of an aircraft and its internal systems 
and components to protect the occupants from injury in the event of a crash. The key 
certification requirements and standards for crashworthiness applicable to transport 
category aircraft are contained in Chapter 525 – Transport Category Aeroplanes of the 
Airworthiness Manual , which is based on the FAA’s Code of Federal Regulations, Title 14: 
Aeronautics and Space, Part 25: Airworthiness Standards: Transport Category Airplanes 
(FAR 25).
1.15.1.1 Aircraft design and certification
When the ATR 42 was introduced in Canada in 1993, TC issued a Type Certificate based on 
the aircraft’s previous U.S. FAR 25 certification in 1985.
Because the certification date was 1985, the ATR 42-320 aircraft was certified as meeting 
the standards of FAR 25 in place at that time, up to and including amendment 54 (1980).
Hence, the ongoing production of the type had to comply only with regulations in effect in 
1980, and not with numerous amendments to the design standards made following that 
date. 
The FAR 25 section that primarily covered crashworthiness in amendment 54 (1980) was 
FAR 25.561, which stated:
(a) The airplane, although it may be damaged in emergency landing conditions on 
land or water, must be designed as prescribed in this section to protect each 
occupant under those conditions.
(b) The structure must be designed to give each occupant every reasonable 
chance of escaping serious injury in a minor crash landing [emphasis 
added] when—
(1) Proper use is made of seats, belts, and all other safety design provisions;
(2) The wheels are retracted (where applicable); and
(3) The occupant experiences the following ultimate inertia forces [acting 
separately] relative to the surrounding structure:
(i) Upward—2.0g.
(ii) Forward—9.0g.
(iii) Sideward—1.5g.
(iv)Downward—4.5g, or any lesser force that will not be exceeded when the 
airplane absorbs the landing loads resulting from impact with an 
ultimate descent velocity of five f.p.s. [feet per second] at design landing 
weight. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 49
(c) The supporting structure must be designed to restrain, under all loads up to 
those specified in paragraph (b)(3) of this section, each item of mass that could 
injure an occupant if it came loose in a minor crash landing.62,63
The design standards did not require an evaluation of the ATR 42-320 structural 
crashworthiness capability at an aircraft level.
This FAR 25.561 standard, from paragraph (b)(3) onward, was updated in 1988 to make an 
adjustment to the ultimate forces and to add a condition that would ensure passenger 
evacuation was not impeded:
(3) The occupant experiences the following ultimate inertia forces acting 
separately relative to the surrounding structure:
(i) [Upward, 3.0g.
(ii) Forward, 9.0g.
(iii)Sideward, 3.0g on the airframe; and 4.0g on the seats and their 
attachments.
(iv)Downward, 6.0g.
(v) Rearward, 1.5g]
(c) The supporting structure must be designed to restrain, under all loads up to 
those specified in paragraph (b)(3) of this section, each item of mass that could 
injure an occupant if it came loose in a minor crash landing.
[(d) Seats and items of mass (and their supporting structure) must not deform 
under any loads up to those specified in paragraph (b)(3) of this section in any 
manner that would impede subsequent rapid evacuation of occupants.]64
Crashworthiness was also enhanced in 1988 by the addition of FAR 25.562, which 
introduced dynamic condition requirements during an emergency landing, in addition to 
the static conditions required by FAR 25.561. FAR 25.562 required that seats remain 
attached to the floor when the floor accelerations reach 14g in a vertical (downward) 
direction and 16g in a longitudinal (forward) direction.
The aviation industry has widely seen the enhancements to FAR 25.561 and the 
introduction of the new FAR 25.562 as a step forward to enhance the crashworthiness 
requirements for transport category aircraft, although these were not applicable to the 
ATR 42. However, these amendments, and even those in effect at the time of this report’s 
 62 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, section 25.561 
(Amendment 25-23, effective 08 May 1970). 
63 The report will use the terms “longitudinal” for forward and rearward, “vertical” for upward and downward, 
and “lateral” for sideward forces.
64 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, section 25.561 
(Amendment 25-64, effective 16 June 1988). 

50 | TRANSPORTATION SAFETY BOARD OF CANADA
publication, do not dictate how the structure of an aircraft is to be designed to give each 
occupant “every reasonable chance of escaping serious injury in a minor crash landing.”65
1.15.1.2 Aircraft energy absorption
Scientific evidence dictates that the only way to achieve the survivability crashworthiness
requirements is to have a structural design that can effectively absorb the impact energy 
through structural deformation or crumpling, so as to attenuate the impact force.
On vertical impact, the lower portion of the aircraft fuselage should progressively collapse 
and crush, thus absorbing part of the kinetic energy and attenuating the severity of the force 
before it can reach the occupants66 and the upper portion of the fuselage. If the structure 
does not collapse and crush to absorb the kinetic energy, then the deceleration profile can 
transfer directly to the cabin and the seated occupants. Such a transfer of forces could cause 
significant structural damage to the fuselage and floor, which would breach the cabin and 
reduce the effectiveness of the aircraft’s restraint system while the occupants are 
experiencing the peak deceleration forces. 
1.15.1.2.1 Previous test involving ATR 42 impact response
In 2006, the FAA performed a vertical drop test on the ATR 42 to determine the impact 
response of the fuselage, fuel system, floor tracks, seats, and anthropomorphic test 
dummies when subjected to a severe, but survivable, simulated crash impact (figures 19
and 20). 
The aircraft was dropped from a height of 14 feet, which resulted in a vertical impact 
velocity of 30 fps (9.1 m/s). Although crushing of the lower portion of the forward and aft 
fuselage sections absorbed much of the impact energy, the following also occurred:
• The lower portion of the centre fuselage section underneath the wing, which was 
essentially the main landing gear housing structure, did not effectively absorb the 
vertical impact energy. As a result, the acceleration force (in g) transferred to the 
cabin floor of the centre fuselage section was more than 2 times higher than the 
acceleration force to the forward and aft fuselage sections. 
• The centre fuselage sustained major structural damage and the upper portion 
collapsed, which was attributed to (1) the inertial load of the wing as a result of the 
high acceleration forces that were transferred and the subsequent failure of 2 main 
supporting frames (lift frames) and (2), the fracturing and failure of the main 
landing gear housing structure along the vertical line in the centre of the fuselage. 
 65 Ibid. (Amendment 25-23, effective 08 May 1970).
66 M. E. Lewis, “Short duration acceleration,” in: D. Gradwell, and D. J. Rainford (eds.) Ernsting’s Aviation and 
Space Medicine, 5th Edition (CRC Press, 2016), pp. 157–164.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 51
• A habitable environment for the passengers in the centre fuselage section was not 
maintained due to the crushing of the upper fuselage section by the wing and the 
intrusion of the main landing housing structure into the cabin. 
• The passenger doors and the 2 emergency window exits were unusable.67
 67 Federal Aviation Administration (FAA), DOT/FAA/AR-05/56, Vertical Drop Test of an ATR 42-300 Airplane, 
(March 2006). 

52 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 19. Photo of main wing collapsing into the centre fuselage during 2006 drop test (Source: U.S. 
Federal Aviation Administration, with TSB annotations)
Figure 20. Photo of reduced habitable (survivable) space in centre cabin as a result of collapsed wing 
and intrusion of main landing gear structure during 2006 drop test (Source: U.S. Federal Aviation 
Administration, with TSB annotations) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 53
1.15.2 Impact sequence of events
During the occurrence takeoff, as aircraft bank oscillations increased in severity, the aircraft 
began to descend and contact trees. The aircraft then collided with the ground in a 32.0° left 
bank with approximately 4° of nose-up pitch. The aircraft then hit more trees and rocky 
ground and slid across the snowy terrain for approximately 9 seconds, travelling about 
90 m. 
On initial impact with terrain, the bottom of the main landing gear housing structure struck 
the ground and high vertical acceleration forces were transmitted to the upper fuselage. As 
a result of the high upper-fuselage forces, the inertial load from the wing and fuel (in the 
wing) crushed down onto the fuselage, resulting in collapse of the centre section of the 
aircraft and in fuel entering the cabin. The surrounding floor structure then also collapsed. 
Flight data analysis after the occurrence determined that at impact, the aircraft had a 
ground speed of approximately 107 knots. As a result, the longitudinal (forward)
deceleration forces in the direction of travel were approximately 4g when the fuselage 
initially collided with the terrain. As the aircraft continued its trajectory, it rotated (or 
yawed) to the left. As a result of this rotation, although the peak longitudinal (forward) 
acceleration force was estimated to be 4g in the direction of travel, the aircraft and its 
occupants also received significant lateral loads nearing 4g. Ground reaction forces in the 
longitudinal (forward) direction then caused a transverse fracture of the fuselage just 
forward of the wing. This transverse fracture resulted in the forward part of the fuselage 
separating from the main section of the fuselage and, without restrictions from the wings, 
this forward section rolled 90° to the right. The remaining section of the fuselage rolled 
approximately 40° to the right because the wing structure restricted further rotation.
1.15.2.1 Reduction in survivable space
The structural examination found that the extent of crushing damage to the bottom of the 
forward and aft fuselage sections by vertical impact forces was rather limited or localized, 
consistent with modest vertical impact energy. 
The damage to the centre fuselage section of the aircraft was similar to that found in the 
FAA’s drop test, although the occurrence aircraft had much lower vertical impact energy 
than the one in the drop test. Specifically, there were the following similarities:
• A much higher acceleration force was transmitted to the cabin floor of the centre 
fuselage section than that to the forward and aft fuselage sections.
• The upper portion of the centre fuselage section was crushed under the inertial load 
from the wing.
• The forward and aft bulkheads of the main landing gear housing structure fractured 
along a vertical line close to the lateral centre of the fuselage.
• The forward and aft spar bulkheads of the main landing gear housing structure did 
not exhibit signs of appreciable crushing in a vertical direction.  

54 | TRANSPORTATION SAFETY BOARD OF CANADA
All of these observations indicate that the lower portion of the centre fuselage section did 
not effectively absorb the vertical impact energy of the aircraft.
The main landing gear housing structure, located beneath the fuselage, directly under the 
centre-forward section of the cabin, did not progressively crush in the same way as the 
remaining fuselage. As a result, similar to what occurred during the FAA drop test, during an 
otherwise survivable impact, the remaining fuselage sustained major structural damage 
when the wing structure directly above the main landing gear collapsed into the cabin and 
the floor surrounding it collapsed, resulting in a loss of survivable space.
Inside the cabin, the last row of passenger seats was upright; however, the seats in the 
remaining rows were progressively displaced vertically toward the ceiling of the passenger 
cabin due to the upward movement of the cabin floor. Objects penetrated the cabin, and the 
aisle became unusable as a result of the displacement of the seats and floor (Figure 21).
Figure 21. Photos of the displaced cabin seats in rows 6 to 11, a tree that had penetrated the cabin (left), 
and the obstruction to the aisle (right). Seats are labelled by row number (6 to 11) from front to back, and 
seat designator (A to D) from left to right. (Source: TSB)
The tops of the seatbacks of the seats in rows 4 and 5 on the right side of the aisle had
contacted or penetrated the overhead luggage compartment. The survivable space for each 
seat in rows 4 to 6 had been reduced to 1 to 2 feet, and the head space had been reduced in 
many other nearby rows (Figure 22). 
Figure 22. Photos showing the reduced survivable space in rows 4 to 6, with seatbacks contacting or
penetrating overhead luggage compartment (Source: TSB)
The transverse fracture and rotation of the fuselage resulted in further breach of the cabin.
As the aircraft continued to slide, trees, beams, and aircraft structure pieces intruded into  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 55
the survivable space. Outside of the main collapsed area, differential crushing of the lower 
portions of the forward and aft fuselage sections also resulted in the collapse of parts of the 
cabin floor in these areas.
1.15.3 Systems to reduce impact injury
1.15.3.1 Tolerance
Human tolerances to dynamic loads vary depending on factors such as the magnitude, 
direction, duration, and onset rate of the impact forces.
68 Aircraft impact forces typically 
involve vertical and longitudinal forces and, occasionally, lateral forces (from the side). 
People withstand longitudinal forces better than they withstand vertical or lateral forces. 
Typical tolerance levels are 45g in the longitudinal (forward) direction, 20g to 25g in the 
vertical (downward) direction, and 20g in the lateral direction, assuming a 0.10 second 
crash pulse and the occupant is suitably restrained.
69
In addition to potential velocity-related injuries, an occupant has the potential to flail 
(uncontrolled arm, leg, and head movements), jackknife (upper torso folds forward or to the 
side), and/or submarine (slide out from under the belt). 
In general, tolerance and response to g forces vary considerably between individuals due to 
factors such as age, physiology, physical health, and fitness. 
Two of the most significant variables that determine how an occupant will cope with impact 
forces that are transferred through the cabin are the position and direction in which the 
occupant is seated (see section 1.15.3.2 Seats), and how well the occupant is restrained (see 
section 1.15.3.3 Restraints).
1.15.3.2 Seats
The regulations for transport category aircraft require that aircraft seats meet specific 
standards for dynamic load protection to ensure that occupants withstand as much of the 
loads that are transferred into the cabin during an impact as possible.
The ATR 42-320 cockpit has 2 forward-facing flight crew seats and 1 jump seat. In the aft
cabin, there is a forward-facing FA seat between the rear entry door and the service door. 
The occurrence aircraft had 22 pairs of passenger seats distributed across 11 rows, with 
2 seats on the left side (seats A and B) and 2 seats on the right side (seats C and D), for a 
total of 44 passenger seats. Each passenger seat was a forward-facing Geven lightweight
passenger seat, and all had been replaced in 2012. The passenger seats were the type with 
 68 D. F. Shanahan, “Human tolerance and crash survivability,” presented at the North Atlantic Treaty 
Organization (NATO) and Research and Technology Organization (RTO) Human Factors and Medicine Panel 
(HFM) lecture series: Pathological Aspects and Associated Biodynamics in Aircraft Accident Investigation, 
NATO RTO-EN-HFM-113 (2004), pp. 6-1 to 6-16.
69 Ibid. 

56 | TRANSPORTATION SAFETY BOARD OF CANADA
locked-out seatbacks, designed to remain upright after flexing following an impact from the 
rear.
Before 1988, seats were designed and tested to withstand inertial loads from the occupants 
of 9g in the longitudinal (forward) direction, 4.5g in the vertical (downward) direction,
and 1.5g in the lateral directions.
70 In 1988, the standard was changed and since then, it has 
required designs to meet an increased inertial load from the occupants acting on the seats 
in vertical (downward) direction (6g) and lateral direction (4g).
71
At the same time, an emergency landing dynamic conditions standard72 was added that 
required all seats to be tested to withstand floor acceleration of 16g in the longitudinal 
(forward) direction and 14g in the vertical (downward) direction. As well as protecting 
against acceleration forces, the new standard required that occupants be protected from 
head injury as a result of contacting the seat in front of them, or other aircraft structure.
Because the ATR 42 had been designed before 1988, when it was introduced into Canada in 
1993, TC issued a Type Certificate that permitted the continued use of seats designed for 9g, 
4.5g, and 1.5g inertial loads in the respective directions, and did not require head impact 
protection. The Geven lightweight passenger seats met this original requirement, having 
been tested to withstand ultimate inertial loads of 9g, 7.2g, and 4g, respectively, and the FA 
seat in the rear of the cabin was tested to withstand loads of 9g, 7.6g, and 3g, respectively.
1.15.3.3 Restraints
As is typical on most transport category aircraft, all passenger seats were equipped with 2-
point lap belts, without associated shoulder harnesses. The passenger 2-point lap belt does 
not restrain the upper torso and, as a result, passengers have a large flail envelope, allowing 
unrestrained torso, arm, and head movements on impact. In the event of an accident, 
occupants with 2-point lap belts are at a greater risk of concentrated acceleration forces 
around the hips and abdomen and can be at risk of injury as a result of potential flailing and 
jackknifing.
The flight crew and FA seats were each equipped with 4-point safety harnesses, and these 
were being worn at the time of impact. Four-point harnesses are known to be more effective 
at protecting the occupant, as they spread the load across the body.
The effectiveness of the overall restraint system relies on the seat remaining attached to the 
aircraft. On the occurrence aircraft, all of the seat structures were attached directly to the 
floor, and the floor deformation on impact significantly reduced the overall restraint 
effectiveness, regardless of seat or belt type.
 70 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, section 25.561 
(Amendment 25-23, effective 08 May 1970).
71 Ibid. (Amendment 25-64, effective 16 June 1988).
72 Ibid., section 25.562 (Amendment 25-64, effective 16 June 1988). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 57
As parts of the aircraft floor collapsed, passengers and crew experienced vertical, 
longitudinal, and lateral forces, but with reduced restraint protection. Most passenger seats 
remained in place, although they were displaced from the collapse and distortion. However, 
seats A and B in row 3 were ejected out of the aircraft through the transverse fracture. The 
passenger in seat 3B was ejected with the seat, but the passenger in 3A was projected into 
the back of seat 2B, slipping from his belt as the seat departed the aircraft.
The captain’s seat remained intact, but the floor beneath the seat collapsed as part of the 
initial impact forces. The integrity of the overall captain’s restraint system was 
compromised as a result.
The FA seat failed during the impact and, as a result, the attached restraint system was 
ineffective.
1.15.3.3.1 Child restraint system
The ATR 42-320 has no child restraint systems, nor is the aircraft required to have such 
equipment.
In 2015, following its investigation into the December 2012 low-energy rejected landing 
and collision with terrain in Sanikiluaq, Nunavut,73 the TSB found that infants and children 
who are not properly restrained are at risk of injury and death, and may cause injury or 
death to other passengers in the event of an accident or turbulence. 
It further concluded that, if new regulations on the use of child-restraint systems are not 
implemented, then lap-held infants and young children are exposed to undue risk and are 
not provided with a level of safety equivalent to that for adult passengers. 
Therefore, the Board recommended that 
[t]he Department of Transport work with industry to develop age- and size￾appropriate child restraint systems for infants and young children travelling
on commercial aircraft, and mandate their use to provide an equivalent level 
of safety compared to adults. 
TSB Recommendation A15-02 
In 2017, following its investigation into a March 2015 collision with terrain in Halifax, Nova 
Scotia,
74 the TSB restated the recommendation, after finding that an infant was injured 
because of a lack of appropriate child restraint. That investigation found that
[i]f new regulations on the use of child-restraint systems are not implemented, lap￾held infants and young children are exposed to undue risk and are not provided 
with a level of safety equivalent to that for adult passengers.
 73 TSB Aviation Investigation Report A12Q0216.
74 TSB Aviation Investigation Report A15H0002. 

58 | TRANSPORTATION SAFETY BOARD OF CANADA
When the present report was published, TC’s last response to Recommendation A15-02 had 
been received in February 2021 and was rated by the Board in March 2021 as showing 
Satisfactory Intent.
75
1.15.3.4 Bracing for impact
To mitigate the risk of injury to occupants seated in aircraft seats without torso restraints 
or head impact protection, such as those in the occurrence aircraft, it is important that those 
occupants assume a proper brace position.
In this occurrence, the flight crew, although aware of imminent collision, did not have time 
to communicate a “BRACE BRACE BRACE” command to the cabin. 
Because the FA was not aware of the imminent collision and did not receive any commands 
from the flight crew, she did not provide passengers with any emergency commands, such 
as “Bend over, keep your head down.”
Following the initial impact, although the impact sequence continued for a further 
9 seconds, the FA was unable to issue any commands because her seat had ejected from its 
position, projecting the FA into the aisle.
In an anticipated emergency and if time and circumstances permit, in accordance with 
regulations,76 West Wind FAs are required to provide passengers with an additional 
emergency briefing that includes a demonstration, practice, and observation of the brace 
position(s). 
However, in an emergency that is not anticipated by the cabin crew, or if the cabin crew 
become incapacitated, passengers who have not read the safety features card would have 
no information on how to assume the required brace position. 
West Wind’s pre-departure safety briefing did not include any explanation or 
demonstration of the brace position(s), nor was it required to. Passengers were instead 
instructed to review the safety-features cards, which contained illustrations on how to 
brace. Only those passengers with special requirements were provided with additional 
safety information briefings and/or demonstrations.
Passengers typically pay little attention to safety-features cards.77 A study by the U.S. 
National Transportation Safety Board found that 68% of commercial flying passengers do 
 75 TSB Recommendation A15-02: Required use of child restrain systems, at 
https://www.tsb.gc.ca/eng/recommandations-recommendations/aviation/2015/rec-a1502.html (last accessed 
08 February 2021).
76 Transport Canada, SOR/96-433, Canadian Aviation Regulations, subsection 705.43(4).
77 H. Muir and L. Thomas, “Passenger Safety Information Past and Future,” in: Proceedings of 58th Annual 
International Association for Shell and Spatial Structures (IASS), Moscow, Russia (2005), p. 125. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 59
not read the safety-features cards.78 A 2006 study by the Australian Transport Safety 
Bureau found that 65% of commercial flying passengers do not read the card.79 Instead, 
passengers typically rely more on information provided by the crew at the time of the 
emergency. 
In this occurrence, even if passengers had referred to the safety-features card, the brace 
position information did not reflect current advised brace positions. In 2016, TC issued an 
Advisory Circular80 to provide operators with updated guidance to modify the existing 
Canadian recommended brace position.
It recommended that passengers place their hands down by their lower legs instead of on 
the back of the seat in front of them. This recommendation is intended to reduce the chance 
of limb-flailing injuries and/or of the passenger pushing the seat in front of them forward. It 
also recommended that passengers place their legs either vertically (down) or aft, rather 
than extending them forward, which should reduce the chance of leg-flailing injuries. 
Although TC modified the recommended brace position, the Advisory Circular was not 
mandatory and therefore the continued use of the original brace position was permitted. As 
a result, at the time of the occurrence, the original brace position remained on the ATR 42 
safety-features card, which still advised passengers to place their hands on the seat in front 
of them and did not emphasize the importance of the leg position (Figure 23).
 78 U.S. National Transportation Safety Board (NTSB), Safety Report NTSB/SR-01/01, Survivability of Accidents 
Involving Part 121 U.S. Air Carrier Operations, 1983 Through 2000 (Washington, DC: March 2001), p. 5.
79 Australian Transport Safety Bureau (ATSB), Research and Analysis Report, Aviation Safety Research Grant –
B2004/0238, Public Attitudes, Perceptions and Behaviours Towards Cabin Safety Communications (June 
2006), p. 20.
80 Transport Canada, Advisory Circular (AC) 700-036: Brace for Impact Positions for All Aircraft Occupants, 
Issue 01 (30 September 2016). 

60 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 23. ATR 42 recommended brace position, as illustrated on the safety-features card (Source: West
Wind Aviation L.P.)
In a 2015 accident in Halifax, Nova Scotia, involving a transport category aircraft that 
collided with terrain,
81 similar to this accident, the passengers and cabin crew were not in a 
brace position at the time of the initial impact because no emergency was expected. In that 
occurrence, during subsequent impacts, the cabin crew was able to shout, “Bend over, keep 
your head down.” Some passengers attempted to adopt a brace position, either on their own 
or in response to the shouted command, but they did not know how to properly brace 
themselves because they had not read the safety-features card. 
Passengers involved in that accident had injuries to hands and wrists that were consistent 
with attempting to hold onto the backs of the seats in front of them or placing their hands 
forward to brace themselves. Most of the injuries sustained by passengers in that 
occurrence were consistent with not adopting an appropriate brace position. 
1.15.4 Direct effect on occupants
1.15.4.1 Injuries by location
All passengers and crew were injured during the accident sequence. Many were rendered 
temporarily unconscious. The captain and 9 passengers were seriously injured, and 1 of the 
seriously injured passengers died 12 days after the accident. The severity of the injuries was 
somewhat distributed throughout the aircraft (Figure 24); however, the passenger who was 
fatally injured was seated mid-cabin, directly beneath the wing. 
 81 TSB Aviation Investigation Report A15H0002. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 61
Figure 24. Injury distribution (Source: Avions de Transport Régional, Cabin Crew Operating Manual,
Revision no. 4 [April 2018], with TSB annotations)
1.15.4.2 Injuries to passengers
During the impact and resulting slide, most passengers were thrown about in their seats, 
striking the seats in front of them and then the aircraft structure as a result of the 
acceleration forces and the changing direction of those forces. 
As the impact sequence progressed, passengers experienced more severe flailing injuries 
when the aircraft structure and external objects, such as trees, intruded into their
survivable space. Passengers experienced injuries consistent with acceleration forces, 
jackknifing, and flailing, such as back, head, arm, and leg injuries.
Passengers in the middle-forward left section of the aircraft also suffered crushing injuries, 
such as major head, body, and leg trauma. These injuries resulted from the reduction in
survivable space between the floor above the main landing gear and the collapsed upper 
fuselage. Of the 3 passengers in this area, 2 received serious, life-changing injuries, and the 
third died as a result of these injuries 12 days after the accident.
Back-related trauma was more common in the right middle to rear section of the aircraft. 
This type of trauma is consistent with the lateral forces and rotation applied to this side of 
the aircraft, which resulted in lateral deceleration forces affecting the passengers in seats 
that had a compromised restraint system.
One passenger suffered projection injuries when their seat ejected from the aircraft. Many 
passengers throughout the aircraft had their legs trapped when the floor collapsed, 
resulting in knee and leg bruising. The floor collapse reduced the integrity of the restraint 
system and deformed the seats’ structure, which resulted in many seats being squashed 
together and trapping the legs of the passengers.
Those who braced by placing their arms on the back of the seat in front of them still
experienced flailing-arm injuries. One passenger braced with their head down between 
their legs. This passenger did not have flailing injuries, but they did have head and neck 
injuries from the seat in front of them pushing back into their survivable space. 

62 | TRANSPORTATION SAFETY BOARD OF CANADA
1.15.4.3 Injuries to crew
When the FA’s seat detached during the impact sequence, she became unrestrained and was 
propelled forward into the aisle, suffering multiple projection injuries to the legs, hands,
and head. 
As the floor collapsed underneath the captain’s seat, compromising the restraint system, the 
captain suffered acceleration forces injuries, namely, serious back fractures, which limited 
his ability to evacuate on his own. 
The FO suffered minor flailing and leg-compression injuries as a result of the damaged 
aircraft structure imposing into his survivable space.
1.15.4.4 Injury to infant
An infant, who was held unrestrained on the lap of their parent who was seated in 11C,
experienced projection injuries as a result of hitting the seat in front. This infant then 
experienced crushing injuries when that seat was pushed back into the survivable space.
1.15.5 Effect on evacuation routes
1.15.5.1 Cabin configuration
The occurrence aircraft was configured with a cargo bay toward the front of the aircraft 
between the cabin and the cockpit, a main cabin area with 44 passenger seats and a small 
galley, and a cargo bay at the rear (Figure 25).
Figure 25. Occurrence aircraft’s cabin configuration (Source: Avions de Transport Régional, Cabin Crew 
Operating Manual, Revision no. 4 [April 2018], with TSB annotations)
1.15.5.2 Main and evacuation aisle
Differential crushing of the fuselage area caused the floor and seat tracks to deform, which,
in turn, resulted in a significant reduction or elimination of the main aisle. Without the main 
aisle, passengers did not have access to the primary route to the emergency exits, and many 
passengers had to climb over seatbacks to gain access to an evacuation route.
1.15.5.3 Emergency exits
The ATR 42 has 4 doors in the cabin that can be used as emergency exits by the passengers, 
and a pilot emergency hatch for emergency egress from the cockpit (Figure 26).  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 63
Figure 26. Normal and emergency exits on the ATR 42 (Source: Avions de Transport Régional, ATR 42 
Flight Crew Operating Manual, Revision no. 41 [August 2015], Part 1, Chapter 00, section 30, p. 1, with 
TSB modifications and annotations)
The main entry/exit point for passengers and crew is the rear entry door (L2), which is 
located on the rear left side of the aircraft and is equipped with stairs on the reverse side. 
To open from the inside, this door is manually unlocked by moving the door control handle 
up to the OPEN position and then pushing the door forward until the door and stairs swing 
down to the ground (Figure 27).
Figure 27. In-flight safety card pictorial instruction of how to open the main exit door (Source: West 
Wind Aviation L.P.)
Opposite the rear entry door, on the rear right side of the aircraft, is the service door (R2). 
This door is manually opened outwards and can be used as an emergency exit if required. 
At the front of the passenger cabin, in row 1, there are 2 emergency exits—one located on 
each side of the aircraft (L1 and R1). Both of these emergency exits are removed manually
and must be opened, pulled in, then rotated and thrown out of the aircraft.
All 4 doors can be opened from either inside or outside the aircraft.
The aircraft is also equipped with a main cargo door on the forward left side of the aircraft, 
which provides the main loading point for cargo. This door opens outward either 
electrically or manually (with a hand crank), but can be operated only once unlatched from 
the outside. For this reason, the cargo door is not useful as an emergency exit.
The main access point to the flight deck from the cabin is the cockpit door, which is forward 
of the cargo bay. To exit the aircraft, the flight crew must first go through the cockpit door 
into the cabin, and then out of one of the cabin exits. 

64 | TRANSPORTATION SAFETY BOARD OF CANADA
If the cockpit door is blocked, there is an emergency overhead escape hatch in the cockpit 
that is equipped with a stowed emergency rope ladder and built-in steps for egress. This 
hatch opens inward and can be opened from either inside or outside the aircraft.
1.15.5.4 Effect of damage on exits
The crushing, fracture, and differential rotation of the fuselage resulted in significant 
obstructions to the aircraft’s exits. 
The forward part of the aircraft, including the cockpit, rolled 90° to the right and came to
rest lying on its right side. Emergency exit R1 was squashed at the bottom of the fuselage,
and emergency exit L1 was vertically at the top. The 90° orientation also placed the cockpit 
emergency hatch on the side of the aircraft, where it was partially blocked by trees
(Figure 28). 
Figure 28. Orientation and access to emergency exits L1 and R1 (left image) and the cockpit emergency
hatch (right and left images) (Source: Royal Canadian Mounted Police, with TSB annotations)
Because the main passenger cabin had rolled approximately 40° to the right, the service 
door (R2) was partially blocked by external terrain. The main exit point, the rear entry door 
(L2), was facing up, making it difficult to be opened (Figure 29). 
Figure 29. Orientation of the service door (R2) (left image) and the rear entry door (L2) (right image)
(Source: TSB) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 65
1.15.5.5 Equipment, cargo, and other large masses
The current design standards for transport category aircraft require that equipment, cargo 
in the passenger compartment, and any other large masses must be positioned so that, if 
they come loose, they will be unlikely to prevent the use of any of the escape facilities.
82,83
However, when the ATR 42 was certified, this requirement was not as restrictive, and the 
standard in place at the time only required that the
supporting structure must be designed to restrain, under all loads up to those 
specified in paragraph (b)(3) of this section, each item of mass that could injure an 
occupant if it came loose in a minor crash landing.84
The cabin area of the aircraft was divided by partitions. Some partitions divided the 
passenger cabin from the forward cargo hold and from the rear entry door (L2). 
Examination of the partitions in other West Wind ATRs showed that the partition fixtures 
varied from aircraft to aircraft. Some were attached by cargo poles and some by hinges. In 
all cases, it was observed that these partitions, along with the cargo poles, may be easily 
displaced by limited vertical forces. Some partitions were immediately in front of the 
emergency exits. 
During the accident sequence, many of the partitions became dislodged. The partition that 
separated the forward cargo area from the passenger cabin had dislodged and fallen into
seats 1A and 1B, blocking access and identification of the L1 emergency exit (Figure 30).
 82 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, 
subsection 25.561(c)(1)(iii) (Amendment 25-91, effective 29 July 1997).
83 Transport Canada, Airworthiness Manual, Chapter 525 – Transport Category Aeroplanes, 
subparagraph 525.561(c)(1)(iii).
84 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, subsection 25.561(c) 
(Amendment 25-23, effective 08 May 1970). 

66 | TRANSPORTATION SAFETY BOARD OF CANADA
The partition that 
separated the passenger
cabin from the rear entry
door (L2) was also 
dislodged and fell across 
the door, blocking access 
to the door handle,
which was on the other 
side of the partition
(Figure 31). 
In the forward cargo 
hold, immediately 
outside the cockpit door, 
cargo was secured with 
cargo nets, which were 
hooked onto vertical cargo poles. These cargo poles were latched into the aircraft structure. 
During the accident, the cargo poles became dislodged, and, although the nets remained 
attached, the luggage that was retained by the poles and nets came loose. The loose luggage 
and the dislodged poles and nets blocked the cockpit door, preventing egress from the 
cockpit into the main cabin of the aircraft (Figure 32).
Figure 30. Photos of the L1 emergency exit (dashed line) blocked by displaced partition (solid line) 
(Source: TSB)
Figure 31. Partition displaced toward the aft, blocking access to the L2 
rear entry door handle (Source: TSB) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 67
1.15.6 Post-impact survival factors
1.15.6.1 Environment 
During the accident sequence, the 
aircraft cabin was breached by several 
tree branches, metal beams, panels, and 
other structural hazards. This exposed 
the occupants to the −10 °C ambient 
external temperature and it was dark 
and there was no available light.
Fuel leaked into the cabin and soaked 
the passengers; some got it in their 
eyes, affecting their vision. Some 
passengers were covered in blood, and 
some had lost their glasses. All 
passengers were injured, and most 
were trapped to some degree. Because 
of the angle of the aircraft, those on the 
right side were pushed into the 
intruding aircraft wall and those on the 
left side were crushed and/or hanging 
sideways in their seatbelts. Some 
passengers were partially inverted. 
1.15.6.2 Aircraft evacuation
Figure 33 shows the methods of egress for all aircraft occupants. More details on the 
evacuation of the aircraft are provided in the following sections.
Figure 32. Main cockpit door blocked by loose luggage 
as a result of dislodged cargo pole (Source: TSB) 

68 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 33. Seating plan of occurrence aircraft showing locations of injured passengers and methods of 
egress for all aircraft occupants (Source: Avions de Transport Régional, Cabin Crew Operating Manual, 
Revision no. 4 [April 2018], with TSB annotations)
1.15.6.2.1 Cockpit 
The FO was able to free himself from the right-hand seat. He assessed the normal exit route 
through the cockpit but found it was blocked by luggage that had become loose in the main 
cargo area. 
The FO then freed the captain from the left-hand seat and opened the emergency cockpit 
hatch, because this was the only viable evacuation route. The FO evacuated through the 
cockpit hatch, and the captain was extracted through the cockpit hatch with help from the 
FO and other outside responders.
1.15.6.2.2 Cabin 
The collapse of parts of the cabin floor on impact, followed by a subsequent aircraft fracture 
and rotation, resulted in several factors that significantly impeded the evacuation. 
Once the aircraft came to rest, the FA was able to free herself from under the broken seat 
and attempted to check the outside conditions, in accordance with her FA training. 
However, it was dark both inside and outside. With the aircraft on its right side, the right 
windows were facing the ground and the left windows were facing up.
Due to the transverse fracture, communication from the cabin to the cockpit was disabled, 
and the FA was unable to communicate with the flight crew. Therefore, she initiated an 
evacuation of the passengers. 
The FA reportedly attempted to turn on the emergency lights, but the lights did not activate. 
Later examination of the emergency lights switch on the FA panel found that it was not 
depressed. The floor photo-luminescent strips were not visible or useful because the aisle 
had deformed and collapsed during the impact sequence. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 69
Because there was no cabin lighting, the FA requested a cellphone from one of the 
passengers to use as a light. By this point, other passengers were also turning on their 
cellphone lights.
The FA attempted to open the rear entry door (L2) to evacuate the aircraft; however, the 
door handle was blocked by the adjacent partition that had been dislodged from its 
position. In addition, because the aircraft was positioned at an angle to the right, the rear 
entry door was above the occupants’ heads, making operation difficult in terms of reach and 
strength, even if the handle had been accessible. 
Furthermore, there was no way to evacuate through the front of the aircraft, because the 
cabin and aisle had been crushed inwards. The FA and able-bodied passengers attempted to 
open the service door (R2), which was the only remaining accessible emergency exit; 
however, because the aircraft was lying on its right side, this door was partially blocked by 
external terrain. Passengers and the FA had to kick the door for several minutes before it
eventually opened. 
Fifteen passengers climbed out of or over seats to evacuate via the service door (R2). Some 
of those trapped in the middle of the aircraft had to remove outer clothing to get through 
the remaining gap of 1 to 2 feet leading to the rear exits. Some passengers, including the 
infant, had to be freed by other passengers before they could evacuate. 
One passenger was ejected out of the transverse fracture during the initial impact sequence 
and 2 passengers seated in the front left side of the aircraft evacuated through the fracture. 
It took approximately 20 minutes for the first 17 passengers to evacuate the aircraft. Some 
passengers evacuated but then re-entered the aircraft to help free other passengers. Three
passengers remained trapped in the aircraft, and 1 passenger stayed to provide comfort.
The last passenger was removed from the wreckage 3 hours after the accident.
1.15.6.3 Emergency response
The aircraft came to a stop at 1812:56. The wreckage was in a wooded area, approximately 
600 m from the departure end of Runway 28. This location was close enough to the 
community that cellular service was still available.
Shortly after the end of the impact sequence and before the evacuation, passengers used 
their cellphones to request help by calling, texting, or sending social media messages. The 
FA borrowed a passenger’s cellphone to call 911.
Local people received the messages and calls that were made within minutes of the impact. 
Responders included family members, the 4th Canadian Ranger Patrol Group – Fond du Lac, 
community members, airport employees, and an airport contractor. All responders quickly 
set out to locate the aircraft and help in any way they could.
Because the initial information about where the aircraft went down was not clear, there was 
a delay before rescuers could find the accident site. Once the wreckage had been located, as  

70 | TRANSPORTATION SAFETY BOARD OF CANADA
more community members arrived, they were tasked with getting help, equipment, 
supplies, and directing rescuers to the site. 
The site was dark, and the terrain was covered in snow. There was no road, so access was 
only possible by snowmobile. As more responders arrived, some left to get more help and 
equipment, while others started to assist passengers and crew and to ascertain who still 
needed to be evacuated. 
The airport contractor, once informed of the accident, went to the crash site with highway 
equipment to provide light and to assist with the evacuation.
1.15.6.4 Royal Canadian Mounted Police response
The RCMP received the first of multiple calls regarding the accident at approximately 1815
and proceeded to the airport and the crash site, arriving at approximately 1830. Several 
community members were already at work helping passengers exit the wreckage, 
evacuating passengers using toboggans as they became available.
An aircraft carrying additional RCMP personnel and medical resources to assist at the site 
departed CYSF at approximately 1935. 
1.15.6.5 Rescue
Passengers who had evacuated and the passenger who had been ejected from the aircraft
were transferred to the local Fond-du-Lac medical facility on toboggans and snowmobiles. 
Once there, they were triaged and medically evacuated, if required, to hospitals and clinics 
in Stony Rapids, Prince Albert, and Saskatoon, Saskatchewan. 
The responders also worked to free the passenger trapped on the right side, in seat 4D. This 
passenger was protruding out of a hole on the right side of the aircraft and, after 
approximately 1 hour, was extracted through the hole after responders had enlarged it 
using tools and their hands.
Responders then used equipment to free the trapped passengers in seats 5B and 6A. This 
extraction was difficult because every effort to free the passenger in seat 6A affected the 
passenger in seat 5B. Because of the fuel spilled and the risk of fire, it was impossible to use 
equipment to cut through the metal structures. Once it was available, responders used a 
hydraulic “jaws of life,” without having had any extraction training, to prise the seats and 
structure apart enough to free the passengers.
The passenger in seat 6A was extracted after approximately 1.5 hours. The passenger in 
seat 5B was extracted at around 2120, just over 3 hours after the crash.
1.16 Tests and research
1.16.1 TSB laboratory reports
The TSB completed the following reports in support of this investigation:
• GR301/2017 – Flight Recorders Group Report 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 71
• GR021/2018 – Site Survey
• GR028/2018 – Power Plant Group Report
• GR030/2018 – Photo/Video Group Report
• GR232/2018 – Structural Examination
• LP022/2018 – NVM Data Recovery
• LP008/2019 – Aircraft Ground Icing Analysis
1.17 Organizational and management information
1.17.1 Transport Canada
1.17.1.1 General
TC’s vision is to have a transportation system “that is recognized worldwide as safe and 
secure, efficient and environmentally responsible.”85 For Transport Canada Civil Aviation 
(TCCA), that means “an integrated and progressive civil aviation system that promotes a 
proactive safety culture.”86 One of the main tools TC uses to promote a safe and secure 
transportation system is oversight.87
1.17.1.2 Organizational structure
TC carries out its civil aviation responsibilities through the Civil Aviation Directorate in 
Ottawa, Ontario, and its 5 regional Civil Aviation branches at offices across the country.
Each of these offices is responsible for overseeing TC’s Civil Aviation Program in their
respective region.
1.17.1.3 Evolution of oversight
TC defines oversight as “[a]ctivities that support the systematic promotion, monitoring, or 
enforcement of compliance with Transport Canada requirements governing safety or 
security and that contribute to departmental strategic outcomes.”88
 85 Transport Canada, Aviation Safety Program Manual for the Civil Aviation Directorate, Issue 4 
(31 December 2015), section 3.0, at https://www.tc.gc.ca/en/services/aviation/reference-centre/aviation￾safety-program-manual-civil-aviation-directorate.html (last accessed 10 February 2021).
86 Ibid., section 4.2(1).
87 Transport Canada, Civil Aviation: What we do, https://www2.tc.gc.ca/en/transport￾canada/corporate/aboutus-whatwedo.html (last accessed 10 February 2021).
88 Transport Canada, Civil Aviation – Oversight Program Description and Delivery – Fiscal Year 2018 to 2019, at 
https://www.tc.gc.ca/en/transport-canada/corporate/transparency/civil-aviation-oversight-program￾description-delivery-2018-2019.html (last accessed 10 February 2021). 

72 | TRANSPORTATION SAFETY BOARD OF CANADA
In 2005, TC made a shift to a new approach to its oversight functions with the introduction 
of safety management systems (SMS).
89 Since that time, there has been a significant change
in the way TC conducts oversight of civil aviation in Canada. 
Traditional oversight was largely composed of audits and inspections aimed at ensuring 
regulatory compliance. This approach, however, is only a first step, as ensuring compliance 
with regulations alone does not assure the regulator that identified problems will not recur. 
TC has therefore moved toward a systems approach to oversight whereby, in addition to 
verifying a company’s regulatory compliance, TC examines its internal processes to verify 
that the organization has an effective system to manage the risks associated with its 
operations.
To develop a regulatory environment conducive to the successful implementation of SMS, 
TC has translated its philosophy of greater cooperation into policies and procedures that 
favour the use of an operator’s safety management processes to address issues over the use 
of punitive sanctions. For example, Civil Aviation Directive (CAD) 107-004 states the 
following:
Transport Canada agrees to promote voluntary compliance with regulatory 
requirements, without necessarily resorting to punitive action, by providing 
certificate holders governed by an SMS, the opportunity to determine, by 
themselves, proposed corrective measures to prevent recurrence of a contravention, 
as well as the best course of action to help foster future compliance.
90
1.17.1.4 Transport Canada’s approach to surveillance
Regulatory oversight requires the regulator to 
determine what surveillance activities will be 
carried out, to conduct surveillance activities, 
and to follow up to verify that identified 
deficiencies have been addressed. The sections 
that follow describe TC’s approach to the 
planning, conduct, and follow-up of oversight, 
including the guidance material used by inspectors in each phase—and how that approach 
evolved during the period leading up to and following the occurrence.
 89 Safety management system means “[a] documented process for managing risks that integrates operations 
and technical systems with the management of financial and human resources to ensure aviation safety or 
the safety of the public.” (Source: Transport Canada, Basic Definition: Safety Management Systems, at 
https://www.tc.gc.ca/en/services/aviation/general-operating-flight-rules/safety￾management/systems/definition.html [last accessed 10 February 2021]).
90 Transport Canada, Civil Aviation Directive (CAD) 107-004: Aviation Enforcement – Safety Management 
Systems, Issue 02 (19 August 2009), section 4.0: Policy Statement, pp. 2–3.
Since this accident, TC has initiated a number 
of changes to its surveillance policies and 
procedures. Due to the scope of this 
investigation, the report will focus primarily 
on the policies and procedures in place 
leading up to the accident. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 73
1.17.1.4.1 Surveillance planning
In Issue 06 of TC’s staff instruction (SI) SUR-001, which was in effect at the time of the 
occurrence, surveillance is defined as “all activities directly related to TCCA evaluating an 
enterprise’s compliance with applicable regulatory requirements including assessments, 
program validation inspections and process inspections.”91
TC surveillance of an operator may be a planned activity based on predetermined intervals 
and an approved surveillance plan, or an unplanned activity in response to an unforeseen 
occurrence (accident, incident, or increase in operator risk indicators92 [see 
section 1.17.1.4.2 National Aviation Safety Information Management System]).
In 2009, TC published Issue 01 of Civil Aviation Directive (CAD) SUR-008, establishing the 
following baseline surveillance intervals for all enterprises that are issued a TCCA 
certificate:
• Assessments (for SMS enterprises) will be conducted at 36-month intervals unless 
specific risk indicators indicate that a shorter cycle should be applied.
• Program validation inspections (PVIs) (SMS and non-SMS enterprises) will be 
conducted at 12-month intervals unless specific risk indicators indicate that a 
shorter cycle should be applied.93
On 29 May 2012, TC published Issue 02 of CAD SUR-008, describing TC’s new risk-based 
approach to determining surveillance intervals for all companies, whether or not the 
companies have an SMS.94 According to the revised guidance, “surveillance intervals shall 
range from 1 year (high risk and/or high impact enterprises) to 5 years (low risk and/or 
low impact enterprises).”95
This change in surveillance intervals differs significantly from the recommendations laid 
out in ICAO’s Manual of Procedures for Operations Inspection, Certification, and Continued 
Surveillance, which states that “all significant aspects of the operator’s procedures and 
practices should be evaluated and appropriate inspections, commensurate with the scale of 
the operator’s activities, conducted at least once every 12 months.”96 In addition, ICAO’s 
Safety Oversight Manual states that “Scheduled inspections must be augmented by periodic 
random inspections of all facets of the operation.”97
 91 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), section 2.3.
92 Ibid., section 4.2.
93 Transport Canada, Civil Aviation Directive (CAD) SUR-008: Surveillance Policy, Issue 01 (22 January 2009), 
Appendix A.
94 Ibid., Issue 02 (29 May 2012).
95 Ibid., p. 7.
96 International Civil Aviation Organization (ICAO), document no. 8335, Manual of Procedures for Operations 
Inspection, Certification, and Continued Surveillance, 5th Edition (2010), p. IV-2-2.
97 International Civil Aviation Organization (ICAO), document no. 9734, Safety Oversight Manual, 2nd Edition 
(2006), Part A: The Establishment and Management of a State’s Safety Oversight System, p. 3-17. 

74 | TRANSPORTATION SAFETY BOARD OF CANADA
1.17.1.4.2 National Aviation Safety Information Management System
According to TC’s surveillance planning policy at the time of the accident (i.e., CAD SUR￾008), surveillance intervals were subject to an annual review and were determined using 
the following 2 criteria:
• Risk-indication level: This is a number from 1 (little to no risk) to 5 (significant risk). 
The elements considered in determining this rating are the National Aviation Safety 
Information Management System (NASIMS) risk-indicator number (RIN), the results 
of the most recent surveillance activity, the availability of safety information, and 
whether the company has an SMS.
• Impact-value determination: This is a rating from A (negligible impact) to E 
(extensive impact) that takes into account the number of certificates held, number 
of employees, bases, aircraft types, type of operations, and whether the operator 
conducts international operations.98
At the time of the accident, the primary tool TC used to prioritize surveillance activities was 
the NASIMS. NASIMS was the result of a 2007 TC working group comprising various 
technical specialties formed “to develop a comprehensive risk indicator program.”99
The NASIMS risk-indicator module consists of 77 close-ended questions pertaining to 
10 key hazard areas. Each question is responded to with yes, no, or unknown, and
comments can be added with a justification. According to SI SUR-005 Issue 01, “[q]uestion 
responses must be updated as new safety intelligence is received. This provides a near real￾time risk picture […] .”100
The responses are analyzed to calculate an operator’s RIN. Each year, TC reviews the 
surveillance intervals to prioritize its surveillance activities for each upcoming year.101 In 
addition to the annual review, these surveillance intervals may be adjusted at any time if TC 
determines that such adjustment is warranted by changes in an operator’s risk indicators. 
However, there are no pre-set thresholds that automatically trigger such action.
On 01 April 2019, TC discontinued using the risk indicator module of NASIMS, which 
produced the RIN TC used to support the creation of the national surveillance plan. 
According to TC, the one-size-fits-all approach to risk-based surveillance planning created
 98 Transport Canada, Civil Aviation Directive SUR-008: Surveillance Policy, Issue 02 (29 May 2012), pp. 5–6.
99 Transport Canada, Transport Canada’s Risk Based Surveillance and Planning System, presented at the EASA 
Safety Conference, Safety Oversight: Managing Safety in a Performance Based Regulatory Environment 
(October 2012).
100 Transport Canada, Staff Instruction (SI) SUR-005: Guidance on the Use of Risk Indicators in the National 
Aviation Safety Information Management System, Issue 01 (29 May 2012), section 7.4.
101 Ibid., sections 4.0–9.0. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 75
distortion in the national surveillance plan at the 2 extremes of enterprise complexity 
scales.
102
One of the reasons identified by TC to discontinue the use of the NASIMS was that the 
“quality of the data contained in NASIMS did not always reflect the current risk level 
present in the enterprise at the time the annual surveillance plan was created [...].
[C]onstant reminders had to be issued for the inspectors to populate the database.”103
Some of NASIMS’ other functions are still in use at the time of writing of this report; 
however, TC is looking for a new solution based on business intelligence principles to 
replace NASIMS. At the time of report writing, TC had reverted to using peer groups and 
local intelligence, as detailed in SI SUR-028, for surveillance planning in fiscal year 2019–20, 
until a new system is in place and operational in 2 to 5 years.104
1.17.1.4.3 Conduct of surveillance
Under section 8.7(1)(a) of the Aeronautics Act, the Minister of Transport has the authority 
to conduct inspections to monitor compliance with the Act.
As a result of TC’s shift to a systems approach to oversight, traditional audits and 
inspections have been replaced by system-level and process-level surveillance tools. These 
tools are intended to allow TC’s surveillance “to evolve beyond compliance auditing to 
include the review of an enterprise’s systems to determine if they are effective at achieving 
compliance both currently and on an on-going basis.”105
SI SUR-001 describes each of these surveillance tools in detail. SI SUR-001 has undergone 
multiple revisions since its inception in 2005. At the time of the occurrence, SI SUR-001 
Issue 06, issued on 22 June 2016, was in effect.
1.17.1.4.4 Surveillance findings
According to SI SUR-001, a finding is “a factual account, supported by evidence, of how an 
enterprise is not in compliance with regulatory requirements.”106 In the contemporary 
system-based surveillance model, TC inspectors are required to write findings (stand-alone 
or system-level) against failures (i.e., non-compliance with regulations), and they must be 
documented using a standardized finding form. The finding form identifies the regulation(s) 
not being complied with, as well as examples that demonstrate the non-compliance. 
 102 Transport Canada, Email correspondence with the TSB (12 July 2019).
103 Transport Canada, Email correspondence with the TSB (12 July 2019).
104 Transport Canada, Staff Instruction (SI) SUR-028: Surveillance Planning Instructions – Fiscal Year 2019–2020,
Issue 04 (29 October 2018).
105 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), section 3.0.
106 Ibid., section 2.3. 

76 | TRANSPORTATION SAFETY BOARD OF CANADA
SI SUR-001 requires that the surveillance team ensure that they have sufficient evidence to 
support their observations and any issues of non-compliance before they issue a finding.
107
This means that a finding must be supported by sufficient specific and factual evidence that 
clearly shows how it resulted in the operator being non-compliant with the regulations. If 
there is not enough evidence to support a finding, further sampling must be conducted.108
At the time of the accident, findings of non-conformance identified during systems-level 
surveillance activities were classified as shown in Table 5.
109
Table 5. Transport Canada classification of surveillance findings at the time of the accident (Source: 
Transport Canada, Staff Instruction [SI] SUR-001: Surveillance Procedures, Issue 06 [22 June 2016], 
section 10.2.4)
Classification Criteria
Minor
A finding is considered minor where a surveillance activity has identified that the area 
under surveillance has been maintained and demonstrated to be effective; however, it
requires administrative enhancement. 
Moderate 
A finding is considered moderate where a surveillance activity has identified that the 
area under surveillance has not been fully maintained and examples of non-compliance 
indicate that it is not fully effective; however, the enterprise has clearly demonstrated 
the ability to carry out the activity and a simple modification to their process is likely to 
correct the issue. 
Major 
A finding is considered major where a surveillance activity has identified that the area 
under surveillance has not been established, maintained and adhered to or is not 
effective, and a system-wide failure is evident. A major finding will typically require 
more rigorous and lengthy corrective action than a minor or moderate finding. 
Enterprises are required to submit corrective action plans (CAPs) to TC when findings are 
generated during a surveillance activity. These CAPs, which must be accepted by TC, outline 
how the enterprise plans to address the regulatory non-compliance and ensure ongoing 
compliance in the future. 
According to SI SUR-001, assessments and PVIs must be closed within 12 months of CAP 
acceptance.110 To facilitate this timetable, “the CAP shall aim at having all corrective action 
in place within 90 days of acceptance by the applicable inspector.”111
In some cases, it may take longer than 90 days to implement long-term action items. If a 
CAP will take more than 90 days but less than 1 year to complete, TC must decide whether it 
is acceptable, and that decision must be documented.112 SI SUR-001 also recommends that a 
 107 Ibid., section 9.4.4.
108 Ibid.
109 As of 01 April 2019, TC ceased applying a classification to findings discovered during surveillance activities.
110 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), 
section 12.5(1).
111 Ibid., section 12.5(2).
112 Ibid., subsection 12.5(4)(b). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 77
risk assessment be considered before acceptance; however, it is not mandatory. When CAP 
completion will take more than 1 year, the decision must be escalated to TC regional 
management and the National Civil Aviation Management Executive Committee (NCAMX)113
for review and decision.114
1.17.1.4.5 Assessments and program validation inspections
TC expects companies to proactively manage safety, and to ensure that risks are managed to 
acceptable levels. TC also expects companies to have programs in place to ensure continued 
compliance with regulatory requirements.115 The 2 primary systems-level surveillance tools 
that TC uses to ensure these expectations are met are assessments and PVIs.
According to SI SUR-001, an assessment evaluates the effectiveness and the ability of the 
enterprise’s SMS to maintain compliance with the CARs. TC uses its SMS Framework 
(Appendix A), which outlines the components and elements of an SMS, when conducting an 
assessment. 
While an assessment involves looking at the SMS components and elements, a PVI is “a 
process comprised of research and on-site review of one or more components of a SMS or 
other regulated areas of an enterprise.”116 Assessments and PVIs are conducted at intervals 
based on risk indicators described earlier in this report (i.e., from 1 to 5 years).
According to SI SUR-001, the overall procedures are the same for assessments and PVIs. The 
only differences are the timeline—due to the difference in scope—and the focus of the 
surveillance.117 A PVI is not as in-depth as an assessment; therefore, it typically takes 
considerably less time to complete.
For assessments and PVIs, the Regional Director of Civil Aviation designates a convening 
authority (CA)118 who assembles a team and designates a manager to oversee the activity. 
The team typically consists of civil aviation inspectors in areas of flight operations, 
airworthiness, and cabin safety, as well as administrative personnel.
 113 The National Civil Aviation Management Executive Committee (NCAMX) is TC Civil Aviation’s governing 
body. The committee is made up of the director general, Civil Aviation, as the accountable executive for the 
Directorate, as well as directors at headquarters and in the regions. The committee acts as a forum for high￾level decision making regarding TC Civil Aviation. (Source: Transport Canada, Aviation Safety Program 
Manual for the Civil Aviation Directorate, Issue 04 [31 December 2015], section 4.5).
114 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), 
section 12.5(4)(b).
115 Ibid., section 3.0.
116 Ibid., section 2.3.
117 Ibid., section 7.1.
118 The convening authority is “the individual who oversees and is accountable for the conduct of a surveillance 
activity.” (Source: Ibid., section 2.3). 

78 | TRANSPORTATION SAFETY BOARD OF CANADA
1.17.1.4.6 Process inspections 
A process inspection (PI) is “an in depth review of an enterprise process utilised to produce 
an output to verify whether it functions or not.”119 Unlike assessments or PVIs, a PI looks at 
a single process within an enterprise to verify whether regulatory requirements are being 
met and to ensure that the process is functioning as intended. Any process required by 
regulation may be the focus of a PI.
According to SI SUR-001, “a process inspection shall only be conducted for cause.”120 For 
example, SI SUR-001 states that PIs may be used for several reasons, including:
1. in response to an event or change in risk indicator within an enterprise;
2. in support of a systems level surveillance activity;
3. to gather safety intelligence; or
4. as a scheduled surveillance activity, for example to supplement planned surveillance 
intervals.
When conducted as a stand-alone surveillance activity, the results of a PI can also result in 
initiating, or accelerating timelines for, a systems-level surveillance activity.121
Much like an assessment or a PVI, a PI can generate findings; however, those findings are 
not assigned a classification. Findings resulting from a PI must be addressed using a CAP.122
Timelines for a PI CAP are the same as described for PVIs and assessments. SI SUR-001 does 
not specify a closure time for PIs.
The PI report must indicate whether the process meets applicable regulatory requirements 
and is being followed as published in approved operator manuals, or whether the process is 
not documented, implemented, or effective.
1.17.1.4.7 Follow-up
SI SUR-001 identifies 4 processes that can be used in response to issues of non-compliance 
detected during surveillance activities.123 These processes are, in increasing order of 
severity, 
• CAP;
• enforcement action;
• enhanced monitoring; and
• certificate action. 
 119 Ibid., section 2.3.
120 Ibid., section 17.2.
121 Ibid., section 17.7.3(1).
122 Ibid., section 17.7.2(6).
123 Ibid., section 11.0. 

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Corrective action plan
In line with TC’s cooperative approach to oversight, if issues of non-compliance are found 
during a surveillance activity, operators are given the opportunity to provide CAPs to rectify 
the deficiencies. A CAP “outlines how the enterprise proposes to address identified 
regulatory non-compliances and ensure on-going compliance.”124 CAPs are required by TC 
policy rather than by regulation.
SI SUR-001 states that CAPs must be submitted for each finding and within 30 days of 
receipt of the report of non-compliance, unless there are extenuating circumstances and TC 
approves an extension.125
The CAPs must be completed in accordance with Advisory Circular (AC) SUR-002 and 
submitted to TC for acceptance.
126 AC SUR-002 explains that CAPs must identify the reasons 
underlying the deficiency and include an action plan to address them. In contrast to SI SUR￾001, AC SUR-002 does not specify a requirement to submit CAPs within 30 days of receipt of 
the report.
TC inspectors are responsible for assessing whether CAPs are acceptable, selecting either 
administrative or on-site follow-up to verify implementation of the CAP, and proposing a 
date for the follow-up selected. If CAPs are rejected, they are returned to the operator for 
revision, and the operator then has 7 days to re-submit the revised CAP.127 If the revised 
CAP is rejected, SI SUR-001 indicates that the CA must be informed and that the CA will then 
determine the most appropriate course of action. According to SI SUR-001 section 12.3.4, 
the CA may select any 1 or combination of 
• another opportunity for the enterprise to revise the CAP;
• enforcement action; or
• certificate action. 
Enforcement action
When TC determines that a finding warrants some type of enforcement action (i.e., 
administrative or monetary penalties), a detection notice128 must be submitted to TCCA 
Aviation Enforcement.
 124 Ibid., section 2.3.
125 Ibid., section 12.1.
126 Transport Canada, Advisory Circular (AC) SUR-002: Root Cause Analysis and Corrective Action for TCCA 
Findings, Issue 01 (15 September 2015).
127 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), 
section 12.3.2.
128 A detection notice is a form (form #26-0471) submitted by a TC inspector in response to discovering a 
possible violation of the Aeronautics Act or the CARs. 

80 | TRANSPORTATION SAFETY BOARD OF CANADA
According to SI SUR-001, “CARs cited within the detection notice shall be offence 
creating [sic] provisions, whether they serve as the basis of the finding or quoted within the 
examples of the finding.”129 The detection notice, associated finding(s), and any supporting 
evidence are then forwarded to TCCA Aviation Enforcement for action/follow-up, in 
accordance with the Enforcement Procedures Manual.
130
When a detection notice is submitted, TCCA Aviation Enforcement ensures that the 
condition that led to the enforcement action no longer exists so that the surveillance activity 
can be closed. This is performed via the CAP process.
Enhanced monitoring 
The third option presented in SI SUR-001 for follow-up on issues of non-compliance is 
enhanced monitoring (EM). If EM is the chosen follow-up process, SI SUR-001 directs that it 
must be conducted and closed in accordance with SI SUR-002.
EM is used when a company’s compliance and/or safety record indicates that an increased 
TC presence is necessary to return the operator to a state of compliance and to gain 
confidence that the operator can maintain compliance with regulations. According to 
SI SUR-002, EM is used either when “major findings of systemic failures”131 leading to non￾compliance have been identified during an assessment or PVI, or there is a history of non￾compliance or a failure to demonstrate an ability to comply with regulations.132
The 2 goals of EM are 
• [t]hat the enterprise develops and implements measures to deal with its non￾compliances, ensuring compliance with regulations during and after the period 
of EM; and 
• [t]hat TCCA takes a comprehensive look at the operator’s systems, through 
increased regulatory surveillance activities, in order to confirm the operator’s 
ability to maintain compliance with applicable regulations.133
When EM is to be conducted, the CA appoints an EM manager, who develops a plan for the 
EM. SI SUR-002134 lists a number of elements that must be included in the EM plan:
• Team roles/responsibilities
• Communication protocols
• Activities that are to take place
 129 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), 
section 13.2.
130 The Enforcement Procedures Manual was superseded by Transport Canada, Staff Instruction (SI) 103-001:
Enforcement Procedures, Issue 3 (01 January 2018).
131 Transport Canada, Staff Instruction (SI) SUR-002: Enhanced Monitoring Program, Issue 03 
(02 December 2013), section 2.3(1)(e).
132 Ibid., section 2.3(1)(e).
133 Ibid., section 5.0(1).
134 Ibid., section 7.0(3). 

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• Timeframes
• Conditions for termination of EM
• Budgetary details
• Administrative details relevant to EM
The EM team members are responsible for completing and documenting assigned EM 
activities and for providing updates to the EM manager. 
According to SI SUR-002, EM must be composed of the following:
(a) A verification period of a maximum of 90 days following CAP acceptance during 
which EM team members verify that the enterprise has implemented corrective 
actions; and 
Note: It is acknowledged that certain long term corrective actions may take 
longer than 90 days to implement. However, at a minimum a state of compliance 
must be verified to have been reached by the enterprise during the 90 day 
verification period.
(b) An EM terminating PVI within 12 months of initiation of EM, conducted in 
accordance with SI SUR-001 that, at a minimum, covers the same areas that led 
to the initiation of EM.135
According to SI SUR-002, if an enterprise has not implemented corrective actions effectively 
by the end of the verification period, an EM-terminating PVI will be commenced so that 
appropriate action can be taken.
When an EM-terminating PVI is conducted, the CA must document any decision to take 
action, along with the process used to arrive at the action. If there are no findings, or only 
minor findings that the company subsequently corrects, the company returns to its routine 
surveillance schedule and the EM is closed. If there are moderate and/or major findings, the 
CA determines the most appropriate course of action, on a case-by-case basis, in 
consultation with TCCA regional/headquarters management and enforcement personnel.
Since “EM is not intended to be a perpetual state in which an enterprise operates,”136 if the 
EM-terminating PVI137 determines that the enterprise is not ready to return to routine 
monitoring, it may be subject to another round of EM. Unless authorized by a Regional 
Director of Civil Aviation or a director at TC headquarters, an enterprise can only undergo 
EM twice in succession.138
Without this authorization, the failure of a second EM-terminating PVI results in certificate 
action, in accordance with SI SUR-014.139
 135 Ibid., section 5.1.3(2).
136 Ibid., section 11.1(1).
137 Conducted in accordance with SI SUR-001.
138 Transport Canada, Staff Instruction (SI) SUR-002: Enhanced Monitoring Program, Issue 03 
(02 December 2013), section 5.1.3.
139 Ibid., section 11.1(2). 

82 | TRANSPORTATION SAFETY BOARD OF CANADA
The investigation determined that TC personnel from the Prairie and Northern Region, at 
both the operational and management level, were uncertain of specific steps and timelines 
associated with EM. The EM guidance provided to regional personnel is largely in text 
format and does not include clear decision-making or planning tools such as flow charts, 
timeline templates, or specific checklists to follow to ensure EM is conducted in accordance 
with national policy.
Certificate action
When certificate action is selected as a follow-up process, it must be conducted in 
accordance with the provisions of SI SUR-014. This SI applies to TC inspectors delegated to 
act on behalf of the Minister of Transport for issues related to safety, in relation to 
subsection 7(1) (immediate threat to safety) and subsection 7.1(1) (other grounds) of the 
Aeronautics Act. 
These delegates (acting on behalf of the Minister) may take certificate action under 
section 7.1 of the Aeronautics Act for the following reasons:
• Incompetence: SI SUR-014 defines incompetence as the “inability to perform 
activities that are authorized in a [Canadian Aviation Document] in compliance with 
the regulations and standards applicable to that type of activity.”140 It also states 
that certificate action based on incompetence is applicable only to individuals and 
not to organizations.
• Cessation of meeting qualifications: Certificate action under this section of the Act is 
appropriate when an operator no longer meets the qualifications required for the 
certificate to be issued.141
• Public interest: This category is used “when past non-compliance is serious and 
repeated enough to conclude that there is a risk of further offences.”142 In pursuing 
certificate action under this section of the Act, SI SUR-014 states that it would be 
appropriate to consider records, including accident records; compliance records 
(Aviation Enforcement Division records); and audit, PVI or assessment records 
related to system compliance.
In 2013, TC issued internal process bulletin (IPB) 2013-02 to provide additional direction 
for taking certificate action. The IPB noted that some inspectors believed that they did not 
have the appropriate tools to take certificate action when it is warranted. IPB 2013-02 
 140 Transport Canada, Staff Instruction (SI) SUR-014: Suspension or Cancellation of Canadian Aviation Documents 
for Safety Reasons, Issue 01 (19 July 2011), section 5.4.
141 Ibid., section 5.5.
142 Ibid., section 5.6.1. 

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stated that, when inspectors select certificate action, “functional guidance to support the 
selection is available from the Standards Branch.”143
Further to IPB 2013-02, in 2015, TC issued IPB 2015-03 to provide an overarching policy on 
certificate action within TCCA. In the graduated approach section of the IPB, it stated that 
the decision to take certificate action should be based on several factors, including the 
enterprise’s safety record, the number of findings, the classification of findings, the 
enterprise’s compliance history, and its ability to produce a CAP.144 Specifically, it stated
that the greater the number and classification of findings, the more severe the follow-up 
action. However, IPB 2015-03 did not provide any further guidance to determine the most 
appropriate follow-up action. 
Several TC inspectors that were interviewed during this investigation indicated that they 
perceived that the graduated-approach policy meant that enforcement and/or certificate 
action could only be taken once all attempts at the CAP process had been exhausted. This is 
also consistent with SI SUR-001 Issue 06, which stated that “the CAP process should be 
considered first, followed by Enforcement Action, then Enhanced Monitoring, and finally 
Certificate Action.”145
The investigation also determined that several of the regional TC inspectors involved in a 
2016 assessment of West Wind (see section 1.17.1.7.6 Assessment of West Wind (September 
2016)) believed that detection notices (i.e., enforcement action) could not be filed against an
SMS enterprise unless that enterprise had first been given the opportunity to address the 
issues of non-conformance via the CAP process.
1.17.1.5 Dissemination of policies and procedures at Transport Canada
When a new document is issued or a new issue of an existing document is released, it is 
made available to all TCCA staff as follows:
• It is added to the Civil Aviation Document Collection.
• It is made available via TC’s “myTC Oversight” app.
• It is mentioned in a monthly email sent to all personnel informing them of new 
publications on those platforms.
TC does not have a process to ensure that inspectors read or review newly issued or 
updated publications. Instead, the onus is on the inspectors to do so. 
The investigation determined that inspectors routinely refer to the latest SI that is effective; 
however, they do not normally review the supporting documents, which may supplement 
 143 Transport Canada, Internal Process Bulletin (IPB) 2013-02: Clarification in Respect to Certificate Action in 
Accordance with Sections 7.(1), 7.1(1)(B) and 7.1(1)(C) of the Aeronautics Act, (06 August 2013), p. 6.
144 Transport Canada, Internal Process Bulletin (IPB) 2015-03: Transport Canada Civil Aviation Certificate Action 
Policy, Issue 01 (02 March 2015), pp. 3–4.
145 Transport Canada, Staff Instruction (SI) SUR-001: Surveillance Procedures, Issue 06 (22 June 2016), 
section 10.3(3). 

84 | TRANSPORTATION SAFETY BOARD OF CANADA
the material in the SI. In addition, inspectors typically do not review newly released 
publications unless they become aware that they are pertinent to the inspectors’ activities. 
1.17.1.6 Transport Canada’s efforts to improve oversight of commercial aviation
1.17.1.6.1 General
Since 2015, TC has undertaken a number of initiatives to improve the oversight of 
commercial aviation in Canada. Some of those initiatives are briefly described below.
1.17.1.6.2 Transport Canada’s Civil Aviation Transformation project 
In 2015, TC’s Civil Aviation Transformation project identified national oversight as one of 
several areas requiring action. To address concerns about TC’s national-level oversight of its 
surveillance program (also identified by the TSB),146 TC established a National Oversight 
Office (NOO) and an Oversight Advisory Board (OAB).
1.17.1.6.3 National Oversight Office 
The NOO was established in 2015 to assist with managing the way safety oversight is 
delivered and monitored. The NOO facilitates discussion with management on a monthly 
basis to review national and regional oversight risks related to industry performance and 
compliance as well as oversight delivery performance. This provides a platform for decision 
making on issues related to complex oversight matters as well as continuous monitoring of 
enterprise performance and compliance.
1.17.1.6.4 Oversight Advisory Board 
The OAB was created to provide “support and recommendations to operational branches 
for addressing concerns and processing complex oversight decisions rapidly, effectively, 
and consistently allowing operational branches to take timely action against certificate 
holders that are not operating within regulatory requirements.”147
Before the creation of the OAB, TC regional offices operated largely in isolation when it 
came to selecting the most appropriate method for addressing issues of non-conformance 
identified during surveillance activities. As a result, there was considerable variation among 
how the national standards were being applied across the country.148
The OAB activities began in 2015 and, on 16 March 2016, TC issued IPB 2016-04 to 
communicate temporary changes to SI SUR-001, SI SUR-002, and SI SUR-014 and to provide 
the process to follow and criteria for when to engage the OAB.
IPB 2016-04 states that operational branches must invoke the OAB, by submitting a TCCA 
OAB issue report to the NOO, under the following circumstances:
 146 TSB Aviation Investigation Report A13H0001.
147 Transport Canada, Civil Aviation – Update: Briefing to the Transportation Safety Board [presentation] 
(04 April 2016).
148 TSB Aviation Investigation Report A13H0001. 

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• Issues of non-compliance and decisions pertaining to enhanced monitoring 
involving high profile enterprises
• Enterprises with any combination of:
∘ Multiple/major findings
∘ Repeat findings/non-compliance
∘ Ineffective correction actions
• Impact to the public or Minister
• Certificate actions that may significantly impact the public or public 
confidence149
IPB 2016-04 also encourages operational branches to consult the NOO for guidance on 
applying the criteria above.
In October 2017, TC issued SI SUR-027, formalizing the OAB and outlining its role. In May 
2020, TC released SI SUR-027 Issue 02 which incorporated, and therefore cancelled,
IPB 2016-04. 
1.17.1.7 Transport Canada’s oversight of West Wind Aviation
1.17.1.7.1 Assessment of West Wind (18–22 January 2010)
In January 2010, TC conducted an assessment of West Wind’s recently implemented SMS.
150
The assessment resulted in 13 minor and 6 moderate SMS component-related findings.
Furthermore, the assessment report stated that West Wind’s risk management program 
(i.e., SMS component 3.4 – Risk Management) did not meet the following minimum 
regulatory requirement:
There is a structured process for the management of risk that includes the 
assessment of risk associated with identified hazards, expressed in terms of severity 
and probability of occurrence and where applicable the level of exposure.151
The assessment determined that “West Wind Aviation Limited’s SMS does not fully meet 
applicable regulatory requirements for a system that is documented, implemented, in use 
and effective.”152 West Wind was required by TC policy to produce CAPs to address the 
 149 Transport Canada, Internal Process Bulletin (IPB) 2016-04: Introduction of the Transport Canada Civil Aviation 
Oversight Advisory Board (TCCA OAB), Issue 01 (16 March 2016), p. 4.
150 Transport Canada, Assessment Report – West Wind Aviation between 18–22 January 2010, RDIMS #5635276 
(January 2010).
151 Transport Canada, Advisory Circular (AC) SUR-004: Civil Aviation Surveillance Program, Issue 01 
(19 November 2015), p. 67.
152 Ibid. 

86 | TRANSPORTATION SAFETY BOARD OF CANADA
assessment findings, and on 13 October 2010, TC advised West Wind that all corrective 
action and follow-up had been completed and that the assessment was considered closed.153
Following the 2010 assessment, TC considered West Wind to be an SMS enterprise; 
however, TC was unable to provide any documentation showing that West Wind met all the 
requirements, per the regulations, to have SMS enterprise status.
1.17.1.7.2 Program validation inspection (07–11 March 2011)
From 07 to 11 March 2011, TC conducted a PVI of West Wind. The stated purpose was “to 
verify that the organization has an effective Quality Assurance Program and Operational 
Control System.”154
The resulting PVI report stated, “Your organization has demonstrated that the areas of both 
Quality Assurance and Safety Oversight did not conform to the minimum Regulatory 
requirements as set out in CAR 107.03.”155 The report identified 6 findings of non￾conformance, consisting of 3 classified as minor and 3 as moderate. The 2011 PVI findings 
were dealt with via CAPs that were implemented and closed in a timely manner. On 
16 January 2012, TC informed West Wind that all corrective action and follow-up were
completed and that the PVI was considered closed.
1.17.1.7.3 Program validation inspection (21–24 February 2012)
From 21 to 24 February 2012, TC conducted a PVI of West Wind. The stated purpose was 
“to verify that the organization has an effective Quality Assurance Program and Safety 
Oversight System.” As in the 2011 PVI report, the 2012 PVI report stated, “Your 
organization has demonstrated that the areas of both Quality Assurance and Safety 
Oversight did not conform to the minimum Regulatory requirements as set out in 
CAR 107.03.”156 However, the TC report did not include findings specifically related to West 
Wind’s internal safety oversight. The report contained 5 findings, 1 classified as minor, and 
4 as moderate. The TSB was unable to confirm, with documentation provided by TC, that 
the 2012 PVI CAP had been verified through appropriate follow-up and that the PVI was 
considered closed.
1.17.1.7.4 Program validation inspection (21–25 January 2013)
From 21 to 25 January 2013, TC conducted a PVI of West Wind to “verify that the 
organization has an effective Quality Assurance Program and Safety Oversight System […] to 
 153 Transport Canada, Letter to West Wind – Safety Management System (SMS) Assessment, RDIMS #6207505
(13 October 2010).
154 Transport Canada, Letter to West Wind following 2011 Program Validation Inspection (PVI), 
RDIMS #6595401 (24 March 2011).
155 Ibid.
156 Transport Canada, Letter to West Wind following 2012 Program Validation Inspection (PVI), 
RDIMS #7406167 (16 March 2012). 

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determine the effectiveness of the company’s systems.”157 The PVI team used Appendix B of 
SI SUR-001 to determine the degree of conformance to the CARs and approved company 
manuals/documents.158 The January 2013 PVI resulted in 7 findings, consisting of 3 
classified as minor, 3 as moderate, and 1 as major. The major finding was related to training, 
awareness and competence.
West Wind submitted a CAP to TC on 25 March 2013. On 27 August 2013, TC sent a letter to 
West Wind stating that “all corrective action and follow-up in regards to the PVI findings 
has now been taken; the PVI is considered closed.”159
1.17.1.7.5 Routine surveillance (September 2013–August 2016)
From September 2013 to August 2016, TC conducted the following surveillance activities at 
West Wind:
• Administrative review of documents
• Approved check pilot (ACP) monitors
• Cabin safety in-flight checks
These activities are not governed by SI SUR-001.
During this 3-year period, West Wind was not subject to any additional surveillance 
activities such as assessments, PVIs, or PIs.
1.17.1.7.6 Assessment of West Wind (September 2016)
General
On 20 July 2016, the CA approved an assessment plan for West Wind, and a 12-inspector 
team was tasked to carry out an assessment, in accordance with SI SUR-001, from 29 August 
to 23 September 2016. 
Assessment plan
The objective of the assessment160 was to evaluate West Wind’s SMS, including all 
components and elements; the aircraft maintenance organization; and elements related to 
the Air Operator Certificate, such as training, operational control, quality assurance, and the 
company’s ability to maintain compliance with the CARs.
 157 Transport Canada, Letter to West Wind following 2013 Program Validation Inspection (PVI), 
RDIMS #8192880 (13 February 2013).
158 Ibid.
159 Transport Canada, Letter to West Wind regarding Program Validation Inspection (PVI) Closure, 
RDIMS #8714843 (27 August 2013).
160 Transport Canada, Surveillance Plan – West Wind Aviation (29 July 2016). 

88 | TRANSPORTATION SAFETY BOARD OF CANADA
On-site activities 12–16 and 19–23 September 2016
At the completion of the first on-site period from 12 to 16 September 2016, the assessment 
team identified several issues (Appendix B), including with the operator’s training 
documentation and noted that items from those training programs needed to meet the 
Commercial Air Services Standards (CASS) were missing.
161 As a result, 3 major on-site 
findings were issued detailing concerns with the company’s training programs.
162
On 16 September 2016, West Wind responded to on-site finding 01 with a short-term CAP. 
This short-term CAP, which TC accepted, resulted in West Wind grounding all ATR 42 
pilots163 immediately until the identified issues with the company’s Subpart 705 ATR 42 
training program were resolved. On 19 September 2016, West Wind’s ATR 42 flight crews
were retrained and flight operations resumed.
West Wind also produced short-term CAPs for on-site findings 02 and 03, which TC 
accepted on 20 September 2016. As a result, the company voluntarily grounded its
Subpart 703 and Subpart 704 operations until similar issues with these training programs 
were resolved.
On 19 September 2016, as stated in the surveillance report, “due to the significance and 
classifications of the non-compliances including the systemic failures of West Wind Aviation 
Limited Safety Management System,”164 TC cancelled the remaining assessment activities. 
These planned activities included in-flight inspections, ramp inspections, and interviews.165
On 21 September 2016, discussions took place at TC regarding the possible issuance of a 
notice of suspension (NOS) to West Wind, but an NOS was deemed counterproductive,
because West Wind was working to address the on-site findings.166 A decision was made to 
complete the findings and ensure all supporting documentation was obtained. 
On 23 September 2016, the assessment team held an exit meeting with senior West Wind 
executives and managers. During the exit meeting, the team advised West Wind that the 
deficiencies identified could lead to enforcement action, EM, or certificate action.167
 161 The investigation determined that the missing documented training items did not contribute to this 
occurrence.
162 Transport Canada, Surveillance Report – West Wind Aviation between 12–23 September 2016, 
RDIMS #12439289 (September 2016).
163 Additional information regarding the size and scope of West Wind’s operations can be found in 
section 1.17.2.1 General.
164 Transport Canada, Surveillance Report – West Wind Aviation between 12–23 September 2016, 
RDIMS #12439289 (September 2016).
165 Transport Canada, Assessment Manager Notes – West Wind Aviation, RDIMS #12452092 (September 2016).
166 Ibid.
167 Transport Canada, Exit meeting – West Wind Aviation, RDIMS #12392831 (23 September 2016). 

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Post-surveillance decision making
Within a couple of weeks of terminating the 2016 assessment, and due to the extent and 
severity of the findings, the CA decided that the company would be placed under EM. 
At the time, the regional TC staff’s understanding of TC’s graduated approach did not allow 
for the issuance of an NOS to an SMS enterprise. It was the team’s understanding that an 
SMS enterprise had to be given the opportunity to address the identified areas of non￾compliance via the CAP process. Likewise, there was no consideration given to engaging the 
OAB or the NOO, as team members were unaware of their existence, nor were they aware of
or familiar with the contents of IPB 2016-04. 
Assessment report
On 09 November 2016, the CA sent the assessment report to West Wind.168 The report’s 
executive summary stated that, “as a result of this surveillance activity, West Wind Aviation 
Limited is being placed under enhanced monitoring”169 in accordance with SI SUR-002. The 
report also stated that further details about the EM process would be forthcoming.
The 2016 assessment of West Wind resulted in 10 findings: 3 major findings that were 
issued on site, and 5 additional major findings and 2 moderate findings that were issued 
later (Appendix C). 
The assessment report concluded that the company must submit CAPs to address all 
findings no later than 28 December 2016 and that TC would conduct further follow-up to 
ensure that the CAPs addressed the areas of non-compliance. The report also stated that the 
3 on-site findings would be sent to TC Enforcement for further review and the other 
findings would be reviewed against the supplied CAPs to determine what, if any, further 
action would be required.
Follow-up of the September 2016 assessment
West Wind submitted CAPs for all the assessment findings within the prescribed time limit 
(i.e., within 30 days of receipt of the non-compliance report).
On 22 December 2016, TC advised West Wind that all CAPs had been accepted, and that on￾site verification of CAP implementation and effectiveness would take place at an unspecified 
later date.170 However, at the time of the accident (approximately 12 months later), some of 
the long-term CAPs had not yet been verified by TC. 
 168 Transport Canada, Surveillance Report – West Wind Aviation between 12–23 September 2016, 
RDIMS #12439289 (September 2016).
169 Ibid., p. 3.
170 Transport Canada, Letter to West Wind regard CAP Acceptance, RDIMS #12564422 (22 December 2016). 

90 | TRANSPORTATION SAFETY BOARD OF CANADA
1.17.1.7.7 Enhanced monitoring
On 12 December 2016, TC sent a letter to West Wind advising it again that the company 
would be under EM because of systemic issues of non-compliance identified during the 
assessment.171
TC recorded that it conducted an EM entry meeting with West Wind management over the 
course of 2 days (20–21 December 2016);
172 however, TC was unable to provide the TSB 
with any documentation regarding the details of this meeting.
According to SI SUR-002, the EM surveillance manager must develop an EM plan. The TSB 
requested a copy of the West Wind EM plan from TC. However, TC was unable to produce 
any EM plan or a record that an EM plan had been considered for West Wind. TC was unable 
to provide a reason why a plan for EM of West Wind had not been developed.173
From December 2016 to April 2017, as part of the EM, TC conducted several surveillance 
activities at West Wind that included monitoring training, reviewing quality assurance
audits and SMS reports, and assessing the effectiveness of CAPs that resulted from the 2016 
assessment.
In April 2017, the CA and the EM team reviewed the EM records and concluded that the 
company was unable to demonstrate that it had “the resources, ability or willingness to 
implement systemic changes required to comply with the applicable requirements.” As a 
result, in accordance with SI-SUR-002,174 TC decided that West Wind was not ready to 
terminate EM and that EM would continue.175
From April to December 2017, as part of the continued EM, TC conducted and documented a 
number of surveillance activities that took place during at least 17 separate visits to the 
operator. These activities included monitoring training and check rides, flight operations 
and cabin safety inspections, meetings with management, interviews with prospective 
management candidates, and document and process reviews.
At the time of the occurrence, West Wind had been under EM for almost 12 months;
however, at no point during the EM was the OAB invoked or the NOO consulted with 
regards to how to best handle the oversight and monitoring of West Wind.
1.17.1.7.8 Post-occurrence process inspection and certificate suspension
As a result of the occurrence, on 18–20 December 2017, TC conducted a post-occurrence PI 
at West Wind headquarters. On 20 December 2017, TC issued an on-site major finding due 
 171 Transport Canada, Letter to West Wind, Notification of Enhanced Monitoring, RDIMS #12525576 
(12 December 2016). 
172 Transport Canada, Oversight Advisory Board Issue Report (21 December 2017).
173 Transport Canada, Email to the TSB regarding Enhanced Monitoring Plan (22 June 2018).
174 Transport Canada, Staff Instruction (SI) SUR-002: Enhanced Monitoring Program, Issue 03 
(02 December 2013), section 11.1.
175 Transport Canada, Email to the TSB regarding continuance of Enhanced Monitoring (22 March 2018). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 91
to several areas of non-compliance related to CAR 705.02. TC concluded that there was a 
loss of operational control and suspected this also included the subparts 703 and 704 
operations. 
In response, West Wind temporarily ceased all airline operations (CARs Subpart 705) and,
shortly thereafter, all operations (i.e., including CARs subparts 703 and 704), pending a full 
analysis of its systems and processes.
On 21 December 2017, the OAB convened to help determine the most appropriate course of 
action. Following these discussions, TC was of the opinion that an immediate threat to 
aviation safety existed because of a lack of operational control at West Wind, and that it was 
in the public interest to suspend West Wind’s air operator certificate.176
On 22 December 2017, TC issued an NOS, effective immediately, to West Wind. The NOS 
cited the grounds for suspension, which included the following:
177
• Flight crews are not consistently performing daily aircraft safety checks.
• The operator did not effectively manage flying into possible known icing conditions 
for flights at remote locations.
One of the conditions for terminating the suspension listed on the NOS was for the operator 
to have a functioning SMS that meets the CARs requirements.
1.17.1.7.9 Surveillance planning for West Wind
To gain a better understanding of TC’s surveillance planning for West Wind, the 
investigation looked at the company’s NASIMS risk-profile scores and TC’s interpretation of 
those scores.
From June to November 2012, TC established a NASIMS baseline profile of West Wind using 
the 77 closed-ended questions to produce a RIN.178 Based on the RIN and the risk-indicator 
level, West Wind’s surveillance-interval matrix value was rated as 2D, or low risk, high 
impact (Appendix D). According to CAD SUR-008, an SMS enterprise with a score of 2D is 
subject to a 4-year assessment interval; however, there is no requirement for planned PVIs.
In light of the 2010, 2011, and 2012 findings of non-compliance at West Wind, the 
investigation sought to better understand the rationale behind the 2D rating, as TC was 
unable to provide such a rationale.
The investigation reviewed West Wind’s NASIMS risk profile (Appendix E). When a change 
in response is made to 1 of the 77 questions used to determine the company’s risk profile, 
the date of the change is indicated. If the response to the question does not change, the date 
 176 Transport Canada, Notice of Suspension Air Operator Certificate (22 December 2017).
177 Ibid.
178 Transport Canada, West Wind – NASIMS Risk Indicator [screen print] (23 February 2018). 

92 | TRANSPORTATION SAFETY BOARD OF CANADA
of the last change remains. Of the 77 questions 55 responses were last changed in 2012, 
7 were changed in 2013, none in 2014, 1 in 2015, 13 in 2016, and 1 in 2017.
This absence of timely updates to NASIMS was identified in a previous TSB accident 
investigation report.179 Likewise, the 2012 Spring Report of the Auditor General of Canada
highlighted that “the risk indicators that Transport Canada uses to identify the high-risk 
aviation companies that should be inspected is not always available or kept up to date.”180
The NASIMS printout for West Wind for this time period also states that all responses were 
verified in 2013, 2014, 2015, and 2016; however, for the planning year 2013–14, the 
findings under “surveillance results” were incorrectly classified as moderate, and the major 
finding raised during the January 2013 PVI was not recorded as such. As a result of this 
error, West Wind’s risk-profile score kept the company at a 4-year surveillance interval. 
Had the major finding been correctly entered in NASIMS, the company would have been 
rated as 3E, which would have resulted in the company being subject to a 3-year PVI and 5-
year assessment schedule.
For planning year 2017–2018, the surveillance-interval matrix value was increased to 4E in 
response to the 8 major findings identified during the 2016 assessment. This changed the 
company’s surveillance to a 2-year PVI and 4-year assessment schedule.
1.17.2 West Wind Aviation L.P.
1.17.2.1 General
West Wind was established in 1983. West Wind’s corporate offices and its main operating 
base are located in Saskatoon, Saskatchewan. Sub-bases are located in La Ronge and Stony 
Rapids, Saskatchewan. At the time of the occurrence, the company employed approximately 
153 people, of whom 53 were pilots.
The organization provides both scheduled and non-scheduled domestic and international 
air transportation services for passengers and for all types of cargo, including dangerous 
goods. At the time of the accident, the company operated 5 ATR 42 aircraft under CARs 
Subpart 705, as well as several other aircraft types under CARs subparts 703 and 704.
1.17.2.2 Organizational structure
West Wind’s organizational structure is detailed in Figure 34. On the operational side of the 
structure, the 2 Chief Pilots both report directly to the Director of Flight Operations 
(DFO),
181 whereas the SMS Manager reports to both the DFO and Director of Maintenance.
 179 TSB Aviation Investigation Report A13H0001.
180 Office of the Auditor General of Canada, 2012 Spring Report of the Auditor General of Canada (April 2012), 
Chapter 5.
181 At West Wind, the Director of Flight Operations assumed the regulatory role of Operations Manager. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 93
Figure 34. West Wind’s organizational chart (Source: West Wind Aviation L.P.,
West Wind Aviation 705 Operations Manual, Amendment 34 
[21 December 2015])
1.17.2.2.1 Personnel changes
Between 2010 and 2017, there were 7 personnel changes to the DFO position and
4 personnel changes to the Chief Pilot 703/704 position. 
On 19 September 2016, the DFO assumed the additional role of acting Subpart 705 Chief 
Pilot, to replace an interim Chief Pilot who was retiring later that month. Shortly thereafter, 
the company completed an internal risk assessment to examine the risks of replacing the 
previous Chief Pilot, who had occupied that position for the past 13 years. 
The risk assessment identified the risk of assigning the DFO to hold the Chief Pilot position 
until a permanent candidate could be found as “changes in management can result in a loss 
of operational control.” The risk was assessed as “low,” and a CAP was developed and 
accepted by the DFO. 
The report outlined various risk controls related to the hiring of a new chief pilot; however, 
no risk controls were focused on the additional pressures on the DFO due to the increased 
workload associated with assuming the chief pilot duties, as this pressure was not 
specifically identified as a risk.182
On 22 December 2016, TC approved the dual-role position of DFO and Subpart 705 Chief 
Pilot for a period of 1 year ending 01 January 2018.183 By the end of December 2016, the 
 182 West Wind, SMS Process Report RMR003647 (26 September 2016).
183 Transport Canada, Letter to West Wind regarding approval of dual role, RDIMS #12567088 
(22 December 2016). 

94 | TRANSPORTATION SAFETY BOARD OF CANADA
DFO had taken on the Subpart 705 Chief Pilot roles and responsibilities. At the same time, 
the position of Director of Regulatory Standards and Compliance was eliminated at West 
Wind, and the duties assigned to this position were transferred to the DFO.
In the summer of 2017, the DFO announced his retirement effective 03 November 2017. 
Because this change could present a risk to operations, West Wind carried out a safety 
case184 in August 2017.185 The safety case, which West Wind submitted to TC as part of the 
application/approval process for the appointment of a new DFO, identified several risk 
areas and control measures to reduce the risks associated with hiring a new candidate. 
Following the departure of the DFO, and approximately 1 month before the accident, West 
Wind assigned different individuals to the Subpart 705 Chief Pilot and the DFO positions, 
putting an end to the dual role.
1.17.2.3 West Wind’s operations manual
West Wind policies common to all company flight operations are contained in the West 
Wind Aviation L.P. Operations Manual (COM). This manual is comprised of several parts: 
West Wind Aviation 705 Operations Manual, West Wind Aviation 703/704 Operations Manual,
Flight Dispatch Operational Control Manual, and Flight Crew Training Manual.
The COM provides information required by the CARs and the CASS, and is intended to 
implement, and in some instances supplement, the requirements of the CARs and CASS. The 
West Wind COM and amendments were reviewed and approved by TC.
Flight operations staff are required to be familiar with the contents of the COM and to 
comply with its policies and procedures. Training provided by the company to its 
employees is required to cover the necessary information detailed in the company manuals, 
procedures, and TC regulations.
1.17.2.4 West Wind’s methods of monitoring flight operations
West Wind employed several methods to monitor flight crew performance and adherence 
to company policies and procedures, including:
• initial technical ground training, which provided an opportunity to indoctrinate 
pilots with the company’s operating philosophy, policies, and procedures (West 
Wind COM), AFM, FCOM, Quick Reference Handbook, and the West Wind ATR 42 
standard operating procedures (SOPs);
• initial simulator training, in which pilots received training that reinforced the 
company’s operating philosophy, policies, and procedures;
 184 Safety cases help organizations anticipate hazards that can result from organizational change. (Source: 
Transport Canada, Advisory Circular [AC] 107-001: Guidance on Safety Management Systems Development, 
Issue 01 [01 January 2008].)
185 West Wind, Safety Case, Management Change Executive Summary (August 2017). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 95
• pilot proficiency checks, which were performance checks conducted in a simulator 
to verify that pilots had met the required standard and to validate the training 
process;
• line indoctrination, which was conducted by training pilots to expose pilots to the 
company’s operational environment and to further reinforce the company’s 
operating philosophy, policies, and procedures;
• line checks, which were conducted at the completion of line indoctrination to verify 
that pilots’ performance met the required standard;
• recurrent training, which involved annual ground and simulator training that 
provided opportunities to reinforce the company’s operating philosophy, policies, 
and procedures;
• recurrent pilot proficiency checks and line checks, which provided another 
opportunity annually for the company to verify that pilots met the required 
standard and to verify their compliance with company policies and procedures;
• line reports, which provided company management with a limited opportunity to 
monitor flight operations as reported by captains; and
• management flying, which involved company flight operations managers flying 
periodically with line pilots, and provided managers with an opportunity to directly 
observe pilot performance.
1.17.2.4.1 Flight data monitoring
Flight data monitoring (FDM) is a program to improve flight safety by providing more 
information about, and greater insight into, the total flight operations environment through 
selective automated recording and analysis against objective data generated during flight 
operations. FDM is also known as flight operational quality assurance (FOQA) or flight data 
analysis.
An FDM program is intended to enable an operator to identify, quantify, assess, and address 
operational risks through discreet and anonymous collection of electronic flight data from 
routine operations. Proactive and non-punitive analysis of this de-identified data is used to 
improve aviation safety through development and upgrade of training programs, policy, and 
procedures to address the identified risk areas and to measure the results of these 
initiatives.
FDM has been implemented in many countries, and it is widely recognized as a cost￾effective tool for improving safety. Many carriers in the U.S. and Europe have had the 
program for years.
In Canada, carriers are not required to have an FDM program. However, many operators 
routinely download their flight data to conduct FDM of normal operations. Air carriers with 
FDM programs have used flight data to identify problems such as unstabilized approaches 
and rushed approaches, exceedance of flap limit speeds, excessive bank angles after takeoff,
engine over-temperature events, exceedance of recommended speed thresholds, ground  

96 | TRANSPORTATION SAFETY BOARD OF CANADA
proximity warning system/terrain awareness and warning system alerts; onset of stall 
conditions, excessive rates of rotation, glide path excursions, and vertical acceleration.186
At the time of the accident, West Wind did not have an FDM/FOQA program in place. In 
March 2014, a new employee was hired who eventually, after the 2016 TC assessment, 
became the FOQA coordinator and the security and dangerous goods coordinator. The new 
FOQA coordinator began efforts to implement a formal FOQA system, but West Wind 
management put these efforts on hold when the regulator began EM. As a result, there was 
no FOQA or FDM program in place at the time of the accident.
1.17.2.5 Safety culture
Safety culture is defined as the way safety is perceived, valued, and prioritized in an 
organization. Establishing a positive safety culture187 has many challenges; however, it is a 
necessary first step in creating the values, attitudes, and behaviours required for operators 
to effectively manage the risks associated with their operations. In practical terms, a 
positive safety culture can in part be built or supported by proactive safety management.
According to ICAO,
[a] healthy safety culture actively seeks improvements, vigilantly remains aware of 
hazards and utilizes systems and tools for continuous monitoring, analysis and 
investigation. It must exist in State aviation organizations as well as in product and 
service provider organizations. Other characteristics of a healthy safety culture 
include a shared commitment by personnel and management to personal safety 
responsibilities, confidence in the safety system, and a documented set of rules and 
policies. The ultimate responsibility for the establishment and adherence to sound 
safety practices rests with the management of the organization. A safety culture 
cannot be effective unless it is embedded within an organization’s own culture.188
The strength of an organization’s safety culture starts at the top and is characterized by 
proactive processes to identify, assess, and mitigate operational risks. If unsafe conditions
are not identified, are allowed to persist or are not effectively prioritized by the operator, an 
increased acceptance of such risks can result at all levels of the organization, reducing the 
effectiveness of the operator’s SMS and its safety performance. The hierarchy of influences 
on the way work is accomplished in an organization has been described as the “4 Ps:”189
• Philosophy: An organization’s philosophy provides a broad specification for how it 
wants to operate and communicates values throughout the organization. 
 186 Flight Safety Foundation, “Wealth of Guidance and Experience Encourage Wider Adoption of FOQA,” Flight 
Safety Digest, Vol. 23, No. 6–7 (June–July 2004), pp. 1–98.
187 There are several different ways to describe the safety culture within an organization. Terms such as “healthy” 
or “positive” safety culture are often used interchangeably, as are an “unhealthy” or “negative” safety culture. 
The TSB prefers to describe safety culture as either positive or negative.
188 International Civil Aviation Organization (ICAO), document no. 9859, Safety Management Manual (SMM),
Third Edition (2013), Chapter 2, paragraph 2.6.3.
189 A. Degani and E. L. Weiner, On the Design of Flight Deck Procedures, NASA Contractor Report 177642 (NASA 
Ames Research Center: 1994). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 97
• Policies: An organization’s policies represent broad specifications of how 
management expects tasks to be carried out. 
• Procedures: An organization’s procedures dictate the specific steps an individual 
should take to accomplish a task. They operationalize the philosophy and policies by 
indicating how work will be carried out. 
• Practices: An organization’s practices represent what actually happens in day-to￾day operations. In an ideal world, practices and procedures would be identical. 
However, in reality, practices may differ from procedures for any one of a number of 
reasons. 
One measure of a positive safety culture is alignment across the 4 Ps and efforts to identify
any gaps and continuously improve. If the 4 Ps are not focused on safety, and are not 
aligned to achieve the higher-level goal of safe operations, this is an indication of an 
inadequate safety culture within an organization.
1.17.2.6 Safety management at West Wind 
1.17.2.6.1 General
An SMS provides a formalized approach to managing safety through the use of processes 
and structures an organization puts in place to help it identify hazards and effectively 
mitigate their associated risks.190 According to ICAO, this includes establishing 
accountabilities, policies, and procedures.191 For an SMS to be effective, it must be 
supported by a safety culture that provides the commitment, competence, and cognizance 
to develop and maintain safety management activities.192
The challenge for an organization is to collect and analyze meaningful information that 
provides insights into the actual level of safety within the operation—to identify new 
hazards, defences that are not functioning as planned, procedures that are not being used,
or practices that increase risk. 
As required by CAR 107.01, West Wind established and maintained an SMS for its 
Subpart 705 operations and its approved maintenance organization. The company’s SMS 
was applied to all aspects of West Wind’s operation. The company’s safety policy, which is 
signed by the accountable executive, is included in the SMS manual and states, “All 
employees, including the Accountable Executive, are accountable to ensure activities are 
governed by safety at all times.”193
 190 Transportation Safety Board of Canada, Guide to Investigating for Organizational and Management Factors,
2nd Edition (February 2014), p. 11.
191 International Civil Aviation Organization (ICAO), document no. 9859, Safety Management Manual (SMM),
Third Edition (2013).
192 J. Reason, Managing the Risks of Organizational Accidents (Ashgate Publishing: 1997).
193 West Wind, Safety Management System Manual, Revision no. 15 (03 June 2015), Chapter 1, p. 5.  

98 | TRANSPORTATION SAFETY BOARD OF CANADA
1.17.2.6.2 Safety promotion and training
West Wind promotes safety through bulletin boards, newsletters, messages, internal 
memoranda, lessons learned, and other safety information. 
All employees receive initial and annual recurrent SMS training. West Wind uses online SMS 
training as the primary method of training company personnel. The SMS manual states that 
in-class, one-on-one, or self-paced training may be used to supplement the online training 
program; however, the manual does not explain the circumstances under which this may 
occur.194
The company’s SMS training for employees includes several subjects, including operational 
risk management, hazard identification, and reporting of hazards and errors. The duration 
of the initial and recurrent training sessions is not outlined in the West Wind SMS manual.
1.17.2.6.3 Hazard reporting
According to ICAO, voluntary safety reporting is an important proactive tool that can be 
used to identify hazards before they lead to adverse consequences.195 In this light, West 
Wind’s SMS manual promotes and encourages “open and honest sharing of information,”196
stating that “investigations will be conducted with objectivity and confidentiality as 
referenced by our non-punitive reporting culture.”197
The investigation determined that West Wind encouraged employee hazard reporting and 
provided training on how to use the online SMS reporting system, called Incident Reporter 
(Appendix F).
Hazards reported using Incident Reporter go into the company’s SMS database. Once the 
hazard is in the system, the SMS department investigates and uses the database to capture 
key information about the root cause, the risk analysis completed, and any CAPs or risk 
controls and subsequent follow-up action required.
From 2008 to 2017, employees at West Wind filed a number of SMS reports (Figure 35),
covering a wide range of issues identified throughout the company’s operation. The 
investigation determined that most of the SMS reports were filed reactively to an incident 
that had already occurred; however, there were some proactive reports identified as well.
 194 Ibid., Chapter 4, p. 2.
195 International Civil Aviation Organization (ICAO), document no. 9859, Safety Management Manual (SMM),
Fourth Edition (2018), Chapter 2, paragraph 2.5.2.5.
196 West Wind, Safety Management System Manual, Revision no. 15 (03 June 2015), Chapter 2, p. 3.
197 Ibid. 

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Figure 35. West Wind safety management system (SMS) reports from 2008 to 2017 (Source: TSB, based 
on information provided by West Wind Aviation L.P.)
The investigation determined that from 2014 until the occurrence flight, West Wind
conducted 188 ATR 42 stopovers at CZFD, 101 of which were during the months of October, 
November, and December. The 188 flights had an average stopover time of 25 minutes. This 
quick turnaround time indicates that the ATR 42 was likely never de-iced, and that no 
takeoffs from CZFD were ever delayed or cancelled because of icing conditions. In fact, 
investigation data indicate that some takeoffs likely proceeded with ice on the aircraft. 
Although the 188 flights to CZFD represent a low percentage of West Wind’s total ATR 42 
operations, they are considered representative of West Wind’s operations into remote 
locations.
A review of West Wind’s SMS Incident Reporter system revealed a variety of icing-related 
reports. Some of the reports were related to de-icing procedures, hazards associated with 
some de-icing equipment, and cancellation of flights because ground de-icing equipment 
was unserviceable at airports typically served by de-icing equipment. None of the de-icing 
reports were specific to the inadequacy of de-icing equipment at airports such as CZFD or 
CZWL, or regarding departures performed with ice contamination.
1.17.2.6.4 Safety risk management
One of the 4 components of an SMS is safety risk management.198 According to ICAO, 
[s]afety risk management encompasses the assessment and mitigation of safety 
risks. The objective of safety risk management is to assess the risks associated with 
identified hazards and develop and implement effective and appropriate 
mitigations.199
 198 International Civil Aviation Organization (ICAO), document no. 9859, Safety Management Manual (SMM), 
Third Edition (2013).
199 Ibid., Chapter 2, paragraph 2.15.1. 

100 | TRANSPORTATION SAFETY BOARD OF CANADA
Safety risk management is a process involving the systematic application of management 
policies, procedures, and practices to ensure that risk is reduced as low as reasonably 
practicable.200 It involves observing the organization’s activities and operations, identifying 
hazards or risks, and deciding what mitigating measures to take to reduce the risk. 
According to ICAO, “understanding the system and its operating environment is essential 
for the achievement of high safety performance.”201 This means that environmental factors, 
if present, must be accounted for when conducting safety risk assessments. In addition, risk￾mitigation strategies must be continually reviewed to verify effectiveness. 
Chapter 9 of ICAO’s Safety Management Manual provides some guidance and best practices 
for effective safety risk management. The high-level steps in the process are outlined in
Figure 36.
Figure 36. Safety risk management process (Source: International Civil Aviation Organization 
[ICAO], Doc 9859, Safety Management Manual, 4th Edition [2018], Chapter 9, Figure 9-1, p. 9-11)
A fundamental element of risk management is the proper identification of hazards. If an 
organization does not identify, or improperly identifies these hazards, the rest of the 
 200 International Organization for Standardization (ISO), ISO 31000, Risk Management: Principles and Guidelines, 
1st Edition (15 November 2009).
201 International Civil Aviation Organization (ICAO), document no. 9859, Safety Management Manual (SMM),
Fourth Edition (2018), Chapter 9, paragraph 9.4.3. 

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process will be flawed. According to ICAO, a hazard is defined as “[a] condition or an object 
with the potential to cause or contribute to an aircraft incident or accident.”202 It also goes 
on to say people often confuse hazards with their consequences; the consequence is a 
potential outcome of the hazard. 
If a company is conducting a risk assessment before commencing operations at a new 
airport, it must consider the potential hazards that may be encountered. Once the hazards 
associated with the proposed operation have been identified, then those hazards can be 
examined further to determine whether the risk is acceptable, and whether risk-mitigation 
strategies can be implemented to ensure risk remains at an acceptable level. 
For example, runway contamination represents a hazard. The subsequent loss of control 
that may occur as a result of runway contamination is the potential consequence. Likewise, 
icing is a hazard associated with winter operations, and the potential consequence is a loss 
of control, which could ultimately result in an accident. If a company does not identify 
hazards, it will have an incomplete understanding of the risk that exists and may not 
implement adequate risk-mitigation strategies to ensure adequate safety margins.
Once the hazard and the consequences are clearly identified, the next steps involve 
determining the probability of the adverse consequence and its severity. If the hazard is not 
clearly identified, it is difficult to identify the potential consequences, which, in turn,
adversely affects the accuracy of the risk assessment.
In safety risk management, it can sometimes be difficult to determine which hazards pose 
the greatest risk.203 Additionally, management must also establish suitable structures and 
methods for anticipating, containing, and controlling the effect of unexpected events that 
threaten their organization.
Because of pressure to be cost-effective in an aggressive, competitive environment, 
organizations tend to migrate to the limits of acceptable performance.
204 In other words, 
they “drift.” Organizational drift results from normal processes of reconciling differential 
pressures on an organization (efficiency, capacity utilization, safety) against a background 
of uncertain technology and imperfect knowledge.
205 Therefore, balancing competing 
priorities and managing risk is part of a manager’s decision-making process.
 202 Ibid., Glossary.
203 B. Fishchoff, “Acceptable Risk: A Conceptual Approach,” in Risk: Health, Safety & Environment, Vol. 5, Issue 1 
(1994), pp. 1–28.
204 J. Rasmussen, “Risk Management in a Dynamic Society: A Modelling Problem,” in Safety Science, Vol. 27, 
Issue 2 (1997), pp. 183–213.
205 S. W. Dekker, Drift Into Failure: From Hunting Broken Components to Understanding Complex Systems, 
(Ashgate: 2011). 

102 | TRANSPORTATION SAFETY BOARD OF CANADA
1.17.2.6.5 Operational risk management
According to West Wind’s SMS manual, it has an operational risk management (ORM) 
program consisting of policies, instructions, and procedures for use by employees to 
manage risk during daily operations and for use by management for more complex 
organizational decisions (e.g., planned growth, acquisition, facilities, hiring/training 
procedures). The SMS manual states that West Wind’s objective is to reduce risk to an 
acceptable level and that company personnel are trained to identify hazards and mitigate 
risk using West Wind’s ORM program.206
West Wind’s SMS manual indicates that the company’s ORM program can be used in all 
aspects of day-to-day operations, by flight crew, maintenance personnel, and ground crew, 
with emphasis on the following principles:
• Accept no unnecessary risk
• Make risk decisions at appropriate levels
• Accept risk only when benefits outweigh the costs
• Integrate ORM into planning and policy at all levels
The manual goes on to identify that ORM will, at times, reveal hazards and systemic 
deficiencies that can be addressed by management through a more in-depth risk-control 
process. For this reason, the manual states, “it is essential [that] employees report hazards 
or deficiencies to their supervisor or manager for corrective action.”207
While West Wind’s SMS manual states that ORM can be applied in day-to-day operations, 
and identifies some basic ORM principles, it does not list the steps that operational 
personnel should follow when applying ORM to day-to-day operations.
1.17.2.6.6 Safety reviews
West Wind’s SMS manual describes an internal process called a “safety review,” although 
this process is not required or defined by regulation. According to the SMS manual, safety 
reviews are used for implementing risk controls in response to “detailed planning of a 
proposed task, operation, or operational change.”208
The West Wind SMS Manual states that safety reviews should be developed, at a minimum, 
when
• major operational change is planned,
• major organizational change is planned,
• key personnel change,
• a new route structure is contemplated,
• an additional aircraft type is introduced into the fleet, or
 206 West Wind, Safety Management System Manual, Revision no. 15 (03 June 2015), Chapter 2, section 17.
207 Ibid.
208 Ibid., section 18. 

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• a new geographic area of operation is being planned.
At the time of the occurrence, there was no defined procedure specific to the safety review. 
Instead, when a major change occurred, a safety review was initiated using the Incident 
Reporter system (Appendix F), following the same methodology used for SMS reports 
(referred to as the “flow of a report” methodology) (Appendix G). According to the SMS 
manual, “this process will ensure major changes, proposed tasks or operational changes 
identify the root causes, risks involved and risk controls required.”209
1.17.2.6.7 Commencing operations at Fond-du-Lac
In 2014, West Wind was preparing to activate new routes under contract to Pronto 
Airways,210 a subsidiary of West Wind. Because this involved a new route structure and a 
new geographic area, the company initiated a safety review.
On 28 May 2014, 2 SMS reports were initiated concerning scheduled flights with ATR 42 
aircraft to CZFD and CZWL:
• SMS process report RMR002653: Narrow runways for ATR 42 aircraft
• SMS process report RMR002654: ATR 42 operations into Fond-du-Lac and 
Wollaston Lake
Narrow runways for ATR 42 aircraft
SMS process report RMR002653 identified that the runways at these 2 airports were less 
than 98 feet wide, which would require an amendment to the ATR 42 AFM.211
Two of West Wind’s 5 ATR 42 aircraft already had the appropriate modification, so the 
unmitigated risk was assessed as low. As corrective action, the company issued a 
memorandum to all ATR 42 crew and dispatchers. The memorandum explained that a risk 
assessment had been completed and the risk was considered acceptable, and it included a 
copy of the ATR 42 AFM Appendix 9 regarding operations on narrow runways. 
On 27 June 2014, the SMS investigation was completed. Post-CAP residual risk was rated as 
low. The SMS report was internally audited and closed on 02 September 2014.
At the time of the occurrence, the information contained within the memorandum had not 
yet been incorporated into the COM, even though the COM had been updated twice in 2015.
ATR 42 operations into Fond-du-Lac Airport and Wollaston Lake Airport
SMS process report RMR002654 was initiated to conduct a risk assessment for scheduled 
ATR 42 operations into CZFD and CZWL. The West Wind Subpart 705 Chief Pilot and FA 
 209 Ibid.
210 Pronto Airways was formed in 2006 and was based in Saskatoon, Saskatchewan. In 2015, Pronto Airways’ 
cargo and passenger services were absorbed into those of West Wind Aviation.
211 To operate from runways less than 98 feet wide, the ATR requires modification 8319, which incorporates 
flight crew guidance into Appendix 9, section 7_01.09 of the Airplane Flight Manual. 

104 | TRANSPORTATION SAFETY BOARD OF CANADA
manager, along with the Pronto Airways manager, were assigned to conduct an ORM 
evaluation of the proposed operations. The Pronto Airways manager later moved to West 
Wind and was the captain of the occurrence flight.
In the SMS report, the event or hazard summary was recorded as “conduct risk assessment 
for the ATR 42 conducting flights for Pronto’s scheduled service operations into Fond du 
Lac and Wolliston [sic] Lake.” Similarly, the “detailed description of event/hazard” was 
recorded as “ORM exercise for proposed operations into Fond du Lac and Wollison [sic] 
Lake with the ATR 42.” 
The report focused on issues related to logistics, ranging from commissary supplies, impact 
on dispatch, aircraft movement to/from the terminal (i.e., taxi or tow), training of ground 
services personnel, aircraft loading, to accommodations for crew members who are 
required to spend the night.
The “investigation notes” section of the report mentioned that there was “no de-ice 
equipment able to de-ice an ATR 42;” however, this item was not identified as a hazard, and,
as a result, no risk controls were listed to mitigate the hazard.
The SMS report assessed that the overall risk of the identified hazards was low, with an 
assessment score of 28 using the company’s internal risk assessment tool, and a CAP was 
put in place. The CAP involved conducting an aerodrome inspection, providing ramp staff 
with manuals, and developing clear procedures for commissary, ramp positioning, and 
using auxiliary power units. Once the CAP was in place, the team proposed that the residual 
risk would be lower, as the severity would be decreased from “major” to “minor.” The 
residual risk assessment was still designated as “low” but now with a lower score of 14.
On 10 September 2014, the West Wind DFO accepted the residual risk, and the SMS report 
was audited and closed. The next day, a West Wind ATR 42 completed the first flight into 
CZFD. 
Although the SMS report was closed and operations had commenced, the CAP mitigations 
planned to address the logistical issues had not been implemented when operations 
commenced, and still had not been implemented by the time of the accident. 
1.17.2.6.8 Pronto Airways’ October 2014 review of ATR 42 winter operations
On 23 October 2014, the general manager of Pronto Airways tasked a company pilot with 
reviewing the winter infrastructure to support the ATR 42 flights at CZFD, CZWL, and 2
other airports. The tasking specifically mentioned de-icing equipment, and costs related to 
equipment and training. West Wind was unable to provide any documentation describing 
the outcome of this review or action taken as a result.
On 30 October 2014, the West Wind DFO sent a memorandum to the Pronto Airways 
general manager acknowledging that an estimated 4% of the scheduled flights would need 
to be delayed, rerouted, or cancelled because of icing conditions. The memorandum went on 
to state that “these challenges will not affect the safety of the operation; however, costs  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 105
associated with recovering an aircraft which becomes inadvertently iced up […] must be 
anticipated.”212
The company did not take any formal action to distribute this information to flight crews in 
order to raise awareness that the potential for flight cancellations had been considered. 
Instead, a word-of-mouth informal policy developed to avoid CZFD altogether if there were 
concerns about icing conditions. This unwritten and informal policy did not establish 
specific weather parameters or limits to guide and frame decision making for dispatchers 
and pilots who need to make a go/no-go decision to fly into CZFD.
1.17.3 Previous TSB investigations involving safety management systems and 
oversight
In previous investigations, the TSB has identified several safety deficiencies related to TC’s 
oversight of civil aviation and the implementation of SMS (Appendix H). In particular, the 
TSB has found a number of instances in which TC has been unable to either recognize or 
rectify regulatory non-conformance in a timely manner. In addition, the TSB has identified 
examples of ineffective SMS in both relatively new and mature organizations, and it has 
determined that TC often relies too heavily on a company’s willingness to rectify non￾conformances, rather than its actual capacity to do so. As a result, some companies have 
continued operating in a state of non-compliance for extended periods—in some cases, for 
years. 
Several of these investigations have resulted in findings as to cause and contributing factors, 
findings as to risk, and other findings. In only 1 of those occurrences did TC report having 
taken safety action as a direct result of the SMS/oversight findings.
The TSB investigations of the Buffalo Airways and Ornge air ambulance accidents identified 
deficiencies related to TC’s management of the national oversight program and determined 
there is an over-reliance on an operator’s SMS as a means of ensuring regulatory 
compliance.213 More specifically, both investigations highlighted the importance of a 
flexible, balanced approach to oversight that adjusts to the capabilities of the organization. 
Such an approach should allow for less frequent validation of programs and processes for 
operators that have shown themselves to be proactively managing risk, while providing for 
more frequent oversight to ensure at least a minimum level of compliance with regulations 
for operators at the other end of the spectrum.
While a move toward SMS has great potential to enhance safety by encouraging operators 
to put in place a systemic approach to proactively manage safety, the regulator must also 
have assurances of compliance with existing regulations, particularly for operators that 
have demonstrated a reluctance to exceed minimum regulatory compliance. In order to 
 212 West Wind, Memorandum from the Director of Flight Operations to Pronto: “ATR Winter Operations”
(30 October 2014).
213 TSB aviation investigation reports A13W0120 and A13H0001. 

106 | TRANSPORTATION SAFETY BOARD OF CANADA
assess regulatory compliance, and hence whether risks are sufficiently mitigated, inspectors 
must have appropriate processes and carry out detailed inspections of actual operating 
procedures and practices.
1.17.4 TSB recommendations involving safety management systems and oversight
TSB Aviation Investigation Report A13H0001, which examined the 2013 accident involving 
an Ornge air ambulance at Moosonee, Ontario, highlighted that transportation companies 
have a responsibility to manage safety risks in their operations. Since regulatory 
requirements cannot address all risks associated with a specific operation, companies need 
to be able to identify and address the hazards specific to their operation. Many companies 
are required to have, or have embraced, SMS in their organization. However, approximately 
90% of all Canadian aviation certificate holders are still not required by regulation to have 
an SMS. As a result, TC does not have assurance that these operators can manage safety 
effectively.
Therefore, the Board recommended that
[t]he Department of Transport require all commercial aviation operators in 
Canada to implement a formal safety management system. 
TSB Recommendation A16-12
Even companies with an SMS vary in their ability or commitment to effectively manage risk. 
As a result, the regulator must be able to vary the type, frequency, and focus of its 
surveillance activities to provide effective oversight to companies that are unwilling or 
unable to meet regulatory requirements or effectively manage risk. Furthermore, the 
regulator must be able to take appropriate enforcement action in these cases. As part of 
investigation A13H0001, the TSB found that TC’s approach to surveillance activities did not 
lead to the timely rectification of non-conformance.214
Therefore, the Board recommended that 
[t]he Department of Transport conduct regular SMS assessments to evaluate 
the capability of operators to effectively manage safety. 
TSB Recommendation A16-13
Recent investigations have highlighted the fact that, when faced with an operator that is 
unable or unwilling to address identified safety deficiencies, TC has had difficulty adapting 
its approach to ensure that deficiencies are effectively identified and addressed in a timely 
manner. 
Therefore, to ensure that companies use their SMS effectively, and to ensure that companies 
continue operating in compliance with regulations, the Board also recommended that 
 214 TSB Aviation Investigation Report A13H0001. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 107
[t]he Department of Transport enhance its oversight policies, procedures 
and training to ensure the frequency and focus of surveillance, as well as 
post-surveillance oversight activities, including enforcement, are 
commensurate with the capability of the operator to effectively manage risk. 
TSB Recommendation A16-14
Since that time, the TSB has followed up with TC on action being taken to address these 
recommendations. TC has provided responses to each recommendation indicating what 
action has been or will be taken, and the TSB has assessed those responses. When the 
present report was published, TC’s last responses had been received in September 2020.215
The TSB’s assessment of these responses, as well as previous responses and assessments, 
are available on the TSB website.216
1.18 Additional information
1.18.1 Crew resource management
The objective of CRM is to reduce human error in aviation. CRM is widely accepted as the 
use of all human, hardware, and information resources available to the flight crew to ensure 
safe and efficient flight operations.
In a multi-crew aircraft such as the ATR 42, pilots must successfully interact with each 
other, their aircraft, and their environment, using associated checklists and company SOPs 
to effectively manage threats, errors, or undesired aircraft states that may be encountered. 
As described in the FAA’s Advisory Circular (AC) 120-51E,
measurements of the impact of CRM training show that after initial indoctrination, 
significant improvement in attitudes occurs regarding crew coordination and flight 
deck management. In programs that also provide recurrent training and practice in 
CRM concepts, significant changes have been recorded in flightcrew performance 
during line-oriented flight training (LOFT) and during actual flight. CRM-trained 
crews operate more effectively as teams and cope better with non-routine 
situations.
Research also shows that when there is no reinforcement of CRM concepts by way 
of recurrent training, improvement in attitudes observed after initial indoctrination 
tends to disappear, and individuals’ attitudes tend to revert to former levels.
217
Researchers have recommended that future CRM training should be based on the 
underlying premise that human error is inevitable and cannot be entirely eliminated, and 
 215 An update to TC’s response to TSB Recommendation A16-12 was received in January 2021.
216 Air transportation safety recommendations, at http://bst-tsb.gc.ca/eng/recommandations￾recommendations/aviation/index.html (last accessed 12 May 2021).
217 Federal Aviation Administration (FAA), Advisory Circular (AC) 120-51E: Crew Resource Management Training
(22 January 2004). 

108 | TRANSPORTATION SAFETY BOARD OF CANADA
see CRM “as a set of error countermeasures with three lines of defense.”218 The 1st defence 
is avoiding error, the 2nd defence is trapping errors before they lead to adverse 
consequences, and the 3rd defence is mitigating the consequences of errors that occurred 
but were not trapped.
Modern CRM theory and training now include this premise, and TC defines contemporary 
CRM as a method that
integrates technical skill development with communications and crew 
coordination training and operational risk management by applying threat 
and error management (TEM) concepts.
219
1.18.1.1 Threat and error management
TEM is now considered a key component of effective CRM. The TEM framework has several 
potential applications, including organizational safety management and flight crews
conducting risk assessments. 
The TEM model is a conceptual framework that
• is used to describe how flight crews manage situations they encounter that increase 
the risks associated with flight;
• is used as a tool to analyze the development of situations that culminated in an 
occurrence;
• examines the key elements of threats, errors, and undesired aircraft states; and
• outlines countermeasures that have been shown to be effective in managing those 
elements.
The key principles of TEM are anticipation of, recognition of, and recovery from threats and 
errors. It advocates carefully analyzing potential hazards and taking appropriate steps to 
avoid, trap, or mitigate threats and errors before they lead to an undesired aircraft state.
Flight crews may trap an error by identifying and correcting it, exacerbate an error by 
making a subsequent error, or have no effect on the error as a result of not detecting it or 
ignoring it.
220
The TEM model identifies 5 types of errors:
• intentional non-compliance errors ([deviations from] SOPs)
• procedural errors (slips and lapses in the application of procedures)
• communication errors (information is incorrectly transmitted or interpreted)
 218 R. L. Helmreich et al., The Evolution of Crew Resource Management Training in Commercial Aviation (1999), 
University of Texas at Austin Human Factors Research Project 235.
219 Transport Canada, Advisory Circular (AC) 700-042: Crew Resources Management (CRM), Issue 02 
(14 March 2020), section 2.3.
220 International Civil Aviation Organization (ICAO), document no. 9803, Line Operation Safety Audit (LOSA), First 
Edition (2002), p. 2–4. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 109
• proficiency errors (skill or knowledge is lacking to manage the aircraft)
• operational decision errors (where a decision is taken that increases the risk of the 
flight)221
The most common crew behaviours that manage errors effectively include vigilance,
assertiveness, and inquiry. Although threats and errors occur in the majority of flight 
segments, they rarely carry significant consequences because they are effectively managed 
by the crew. The effective management of risks on the flight deck is inextricably linked to 
effective CRM. When managing errors,
[r]egardless of the type of error, an error’s effect on safety depends on whether the 
flight crew detects and responds to the error before it leads to an undesired aircraft 
state and to a potential unsafe outcome. This is why one of the objectives of TEM is 
to understand error management (i.e., detection and response), rather than solely 
focusing on error causality (i.e., causation and commission). From the safety 
perspective, operational errors that are timely detected and promptly responded to 
(i.e., properly managed), errors that do not lead to undesired aircraft states, do not 
reduce margins of safety in flight operations, and thus become operationally 
inconsequential. In addition to its safety value, proper error management 
represents an example of successful human performance, presenting both learning 
and training value.222
1.18.1.2 Training
At the time of the occurrence, subsection 725.124(39) of the CASS required airline 
operators under Subpart 705 of the CARs to provide all crew members (flight crew and 
flight attendant) with initial and annual recurrent CRM training. 
West Wind provided initial and recurrent CRM training to all crew members, in accordance 
with the existing regulations. West Wind’s initial CRM course was taught during new-hire 
ground schools, while the annual recurrent CRM training and exam were conducted via the 
online training system.
A review of the captain’s training record showed that the captain completed his initial CRM 
training in July 2010 during his initial ground school at West Wind. The captain’s last 
recurrent CRM training at West Wind was completed on 06 June 2017.
A review of the FO’s training record showed that the FO completed his initial CRM training 
in June 2010 during his initial ground school at West Wind. The FO’s last recurrent CRM 
training at West Wind was completed on 17 June 2017.
The standards for CRM training are found in CASS 725.124(39). The standard in effect at the 
time of the accident required initial CRM training to cover the following subjects:
• attitudes and behaviours;
 221 Ibid., pp. 2–3 and 2–4.
222 D. Maurino, “Threat and Error Management (TEM),” presented at the Canadian Aviation Safety Seminar, 
Vancouver, BC (April 2005). 

110 | TRANSPORTATION SAFETY BOARD OF CANADA
• communication skills;
• problem solving;
• human factors;
• conflict resolution;
• decision making;
• team building and maintenance;
• workload management;
• relationship of crew members;
• a review of accidents/incidents of air operators;
• presentation and discussion of selected coordinated emergency procedures 
(practice of CRM skills); and,
• crew member evacuation drills, including debriefing.223
A new revision to the CRM standard was published on 28 July 2017 with an 18 month 
implementation deadline of 31 January 2019. This revision to the standard included a focus 
on TEM; however, this was not required to have been implemented by West Wind at the 
time of the occurrence.
West Wind’s CRM training syllabus was outlined in West Wind’s Flight Crew Training 
Manual, which was approved by TC. This syllabus followed the requirements in
CASS 725.124(39) in effect at the time of the occurrence, but also included a focus on TEM, a 
concept that was not required. However, although the syllabus mentioned TEM, a review of 
the actual training materials did not find any reference to TEM.
1.18.1.3 Procedures
In contrast to training, the concept of threat and error has been incorporated in company 
procedures. West Wind’s SOPs for the ATR 42 include TEM. The SOPs stipulate that, before 
each takeoff, the PIC must conduct a take-off briefing. It also mentions that
[i]nternationally accepted best practices derived from Line Oriented Safety Audits 
(LOSA) and Threat Error Management (TEM) indicates [sic] “Crews that develop 
contingency management plans, such as proactively discussing strategies for 
anticipated threats, tend to have fewer mishandled threats. Crews that exhibit good 
monitoring and cross checking usually commit fewer errors and have fewer 
mismanaged errors.[”] The principals [sic] of TEM are applicable to all flight 
operations.224
The SOPs provide a TEM briefing reference card (Appendix I), which lists several potential 
threats that a crew might encounter on takeoff; however, they also indicate that the list is 
not exhaustive and that crews should brief any additional threats when present. 
 223 Transport Canada, Commercial Air Services Standards, subsection 725.124(39), amended 01 December 2004.
224 West Wind, ATR42 SOP (17 December 2016), section 3.10. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 111
The PIC completed a take-off briefing before departure on the occurrence flight, and the 
briefing addressed a threat posed by the black hole effect.
225 However, the briefing made no 
mention of any threat posed by icing or by contamination of critical surfaces. 
1.18.2 Decision making
Decision making in general is a cognitive process that involves identifying and choosing a 
course of action from several alternatives. Decision making for pilots occurs in a dynamic 
environment and includes 4 steps: gathering information, processing information, making a 
decision, and acting on that decision.
To do this successfully, pilots need to have an understanding of the relevant elements 
involved, a comprehension of their meaning, and the ability to project their future state.226 It 
is important that each pilot establish this situational awareness, but, in multi-crew cockpits, 
it is also important the crew members communicate to establish and maintain a common, 
shared situational awareness. 
There are several risks that can affect decision making: for example, information gathered 
may be incorrect or incomplete; competing tasks may hinder the gathering and processing 
of information; or decision makers may be affected by cognitive biases when processing 
that information. These risks can result in the selection of a choice that is less than ideal. 
There are many defences and aids designed to help pilots make good decisions, including 
rules and regulations, policies and procedures, checklists, training, and CRM/TEM. 
Sometimes pilots attempt to follow this guidance but make a mistake; as a result, the 
outcome will not be as planned. In other cases, pilots make decisions to act outside of the 
guidance, and these adaptations may prove successful, or, in situations such as this one, 
they may not. 
1.18.2.1 Situational awareness
Situational awareness is integral to pilot decision making. Situational awareness is “the 
continuous extraction of environmental information, the integration of this information 
with previous knowledge to form a coherent mental picture, and the use of that picture in 
directing further perception and anticipating future events.”227 Crew members must have a 
 225 The “black hole effect” is a visual sensory illusion that “typically occurs […] over water or over dark, 
featureless terrain where the only visual stimuli are lights located on and/or near the airport.” (Source: Flight 
Safety Foundation, “Approach and Landing Accident Reduction [FSF ALAR] Tool Kit, Briefing Note 5.3: Visual 
Illusions,” Flight Safety Digest Vol. 19, No. 8–11 [August–November 2000], p. 103–108.)
226 M. R. Endsley, “Design and evaluation for situation awareness enhancement,” in Proceedings of the Human 
Factors Society: 32nd Annual Meeting (Santa Monica, CA: 1988), pp. 97–101.
227 SKYbrary, "Situational Awareness," at http://www.skybrary.aero/index.php/Situational_Awareness (last 
accessed 20 May 2020). 

112 | TRANSPORTATION SAFETY BOARD OF CANADA
common, shared situational awareness;228 that is, each pilot’s awareness of the situation is
consistent with that of the other pilot. With a common understanding, crews can effectively 
anticipate and coordinate their actions to perform in an efficient and safe manner to 
manage threats.
Another important aspect of the decision-making process is the concept of shared mental 
models.229 An individual’s mental model depends largely on their understanding of the 
circumstances, expectations about the future, and past experience. The experience or 
knowledge that a person brings to a situation plays a significant role in their decision 
making.
SOPs and checklists are critical information resources that provide procedural guidance to 
pilots for the operation of an aircraft. They assist with pilot decision making and 
establishing shared mental models by providing pilots with predetermined successful 
solutions to various situations and accounting for risk factors that may not be readily 
apparent to a pilot during normal operations or an abnormal/emergency situation.
In a crew environment, every effort should be made to align mental models. If the crew 
members are unable to align mental models, critical information may not be accounted for 
when considering the implications of a situation and formulating plans and contingencies. 
Effective communication plays a critical role in the alignment of the crew’s mental models.
There are several known risks to effective crew communication, including degraded 
performance due to the decision hierarchy between the captain and FO (called the trans￾cockpit authority gradient). Several factors characterize this relationship, notably 
experience and role within the organization. A steep gradient can pose a barrier to 
communication for shared situational awareness and crew decision making. Conversely, a 
flat gradient can create a similar barrier to effective communication. Both pilots can make 
incorrect assumptions about the other pilot’s situational awareness and decision-making 
process, thus limiting communication between the pilots.
1.18.2.2 Cognitive biases
The information gathering and processing required for situational awareness can be 
significantly affected by a number of cognitive biases and heuristics; these factors can lead 
to non-optimal decisions.230
 228 M. R. Endsley, "Toward a Theory of Situation Awareness in Dynamic Systems," in Human Factors Vol. 37, Issue 
1 (1995), pp. 32−64, and E. Salas, C. Prince, D. P. Baker, and L. Shrestha, "Situation Awareness in Team 
Performance: Implications for Measurement and Training," in Human Factors Vol. 37, Issue 1 (1995), pp. 123–
136.
229 T. L. Seamster, R. E. Redding, and G. L. Kaempf, Applied Cognitive Task Analysis in Aviation (Ashgate 
Publishing: 1997).
230 J. A. Wise, V. D. Hopkin, and D. J. Garland, Handbook of Aviation Human Factors, 2nd Edition (CRC Press: 
2016), Chapter 12. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 113
These biases can result from information stored in memory or can affect the way that 
information is remembered. Similarly, these biases can be affected by attention and 
perception, and, in turn, can affect the way that attention is allocated, further affecting 
future perception. 
For example, confirmation bias is the tendency to seek (pay attention to) information that 
confirms what one already believes to be true (based on memory), while, at the same time,
ignoring (paying less attention to) or discounting information that is inconsistent with 
beliefs (perceiving it as less significant).
Plan continuation bias231 is a form of confirmation bias. It is the tendency to continue with 
the original plan even when changing circumstances require a new plan. 
Once a plan is made and committed to, it becomes more difficult to recognize stimuli or 
conditions in the environment that would suggest a new plan is necessary than it would be
if a plan had not already been made. For the new stimulus to be recognized and acted on, it 
needs to be significantly compelling, in that it strongly conflicts with the person’s mental
model or situational awareness. 
By contrast, in cases where plan continuation bias is a factor, people’s understanding of the 
situation gradually diverges from what is later understood to have occurred. This normally 
happens because early and sustained cues that suggested the plan was safe were compelling 
and unambiguous, and later cues that suggested the situation was changing were much 
weaker, difficult to process, ambiguous, or contradictory.232
1.18.2.3 Adaptations 
Adaptations are decisions to deviate from formalized rules or procedures that are 
intentionally performed with the individual being aware that their actions are contrary to 
the rules. Adaptations are often a result of not fully understanding the purpose of the rule or 
procedure, not anticipating the potential consequences of deviating from the rule, or from 
perceiving that the work can be accomplished more efficiently through an adaptation. 
Adaptations can be systemic practices not unique to one person or one crew.
There are 4 main types of adaptations: exceptional, routine, situational, and optimizing.
Exceptional adaptations are deviations that occur in only rare or special circumstances. 
Individuals make such adaptions when they are problem solving in unusual situations in 
which they believe the known rules and procedures do not apply. Because exceptional 
adaptations are rare and novel, it can be difficult to develop specific defences to address this 
behaviour, aside from standard CRM and TEM training. 
 231 B. A. Berman and R. Key Dismukes, "Pressing the Approach," in Aviation Safety World (December 2006), 
pp. 28–33.
232 S. Dekker, The Field Guide to Understanding Human Error (Ashgate: 2006). 

114 | TRANSPORTATION SAFETY BOARD OF CANADA
Routine adaptations are deviations repeated over time, which have become standard 
practice. They may have come into being because the procedure is considered unnecessary, 
difficult, time-consuming, or unworkable, or because it is simply not enforced. Because 
these adaptations are routine, the behaviour may be automatic or unconscious, but the 
person is aware that the formal procedure is not being followed. Management tools to 
address routine adaptations233 can include regular rationalization or simplification of the 
rules, or rewards for compliance. 
Situational adaptations are deviations when there is pressure to get the job done and/or
there are constraints on the availability of resources. These include the design and 
condition of the work area, equipment availability and design, time pressure, number of 
staff, supervision, and external environmental factors. Management tools to address 
situational adaptations234 can include making procedures realistic, involving employees in 
developing rules, improving the level of resources, and increasing supervision.
Optimizing adaptations are deviations that are actioned in order to achieve a personal or 
organizational goal. These involve making a decision that is in the person’s or organization’s 
perceived best interest. An example is pushing limits to achieve a salary bonus or to achieve 
a work goal to please a customer or supervisor. Management tools to address optimizing 
adaptations include making rules easier to follow through simplification and open 
communication between management and employees about the recognized hazard. 
While companies prescribe policies and SOPs to set boundaries for safe operations, 
individuals may gradually test these boundaries to become more productive or obtain some 
other benefit. This experimentation leads to adaptations of procedures and to a shift beyond 
the prescribed boundaries described in the SOPs toward unsafe practices. Without 
intervention, the communication of successful adaptations among crew members tends to 
lead to their spread throughout an organization.
Similarly, when adaptations of any type are performed with no adverse consequences, they 
can persist and become standard practice. This way of working becomes normalized and 
can erode the safety margins that the rules and procedures were intended to provide. As the 
adaptations slowly become normal behaviour, it becomes less likely that the persons 
involved will recognize the risk with the associated adaptation. 
Without regular supervision, education, and enforcement of the expected boundaries, 
individuals are likely to continue to adapt procedures until the edge of the actual unsafe 
boundary is found, by crossing it, and becoming involved in an accident. 
 233 Australian Civil Aviation Authority, SMS for Aviation – A Practical Guide, Booklet 6: Human Factors, 
2nd edition (December 2014), p. 15.
234 Ibid. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 115
1.18.3 Aircraft critical surface contamination
1.18.3.1 Clean aircraft concept
On 10 March 1989, an Air Ontario Fokker F-28 MK 1000 crashed on departure from Dryden, 
Ontario, just beyond the end of the runway. On board were 65 passengers and 4 crew 
members. Three crew members and 21 passengers died as a result of the crash. The aircraft 
was destroyed in the post-impact fire.
A Commission of Inquiry into this accident made several recommendations to address the 
safety deficiencies identified during the investigation. One of these recommendations was 
the following:
The Department of Transport immediately develop and promulgate an Air 
Navigation Order applicable to all aircraft that would prohibit take-offs when any 
frost, snow, or ice is adhering to the lifting surfaces of the aircraft, and the 
Department of Transport provide guidelines to assist aviation personnel in 
conforming to the amended orders.235
The Department of Transport responded to this recommendation by publishing an 
amendment to the Air Regulations. This new regulation, published in the Canada Gazette on 
21 November 1990,
236 subsequently became CAR 602.11(2): “No person shall conduct or 
attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its 
critical surfaces.”
As a result of this recommendation, there now exists an array of administrative defences in 
place to ensure that crews and other operational persons understand the need to ensure
that, before any takeoff is attempted, the aircraft is “clean,” meaning free from critical 
surface contamination. This is called the “clean aircraft concept.”
1.18.3.2 Direction from Transport Canada
1.18.3.2.1 Canadian Aviation Regulations
The CARs provide the regulatory grounds for the implementation of the clean aircraft 
concept. As stated in CAR 602.11:
(1) In this section, critical surfaces means the wings, control surfaces, rotors, 
propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing 
surface of an aircraft and, in the case of an aircraft that has rear-mounted 
engines, includes the upper surface of its fuselage.
(2) No person shall conduct or attempt to conduct a take-off in an aircraft that has 
frost, ice or snow adhering to any of its critical surfaces.
[…]
 235 Commission of Inquiry into the Air Ontario Crash at Dryden, Ontario, Final Report (1992), Volume III, p. 1203 
– MCR 2.
236 Air Regulation 540.2(5), Canada Gazette, Part II, Vol. 124, No. 24. 

116 | TRANSPORTATION SAFETY BOARD OF CANADA
(4) Where conditions are such that frost, ice or snow may reasonably be expected to 
adhere to the aircraft, no person shall conduct or attempt to conduct a take-off 
in an aircraft unless
[…]
(b) for aircraft that are operated under Subpart 5 of Part VII, the operator has 
established an aircraft inspection program in accordance with the Operating 
and Flight Rules Standards, and the dispatch and take-off of the aircraft are in 
accordance with that program.
[…]
(6) Where, before commencing take-off, a crew member of an aircraft observes that 
there is frost, ice or snow adhering to the wings of the aircraft, the crew member 
shall immediately report that observation to the pilot-in-command, and the 
pilot-in-command or a flight crew member designated by the pilot-in-command 
shall inspect the wings of the aircraft before take-off […].
237
1.18.3.2.2 Operating and Flight Rules Standards
The Operating and Flight Rules Standards lay out the specific methods that operators need 
to follow to comply with the associated regulations. Regarding the inspection program 
required under CARs 602.11(4)(b), the introduction to Standard 622.11 – Ground Icing 
Operations, states the following:
In order to operate an aircraft under icing conditions in accordance with the 
requirements of CAR Section 602.11, an operator must have a program as specified 
in these standards and the dispatch and take-off of the aircraft shall comply with 
that program. These Ground Icing Operations Standards specify the program 
elements, for both operations and training, that shall be addressed in an operator's 
Ground Icing Operations Program and described in the appropriate operator's 
manuals.238
The standard lists the program elements that must be included in the operator’s ground 
icing operations program (GIOP) and manuals, and what must be included within the 
elements. These elements are the operator’s management plan, the aircraft de-icing/anti￾icing procedures, the holdover timetables, the aircraft inspection and reporting procedures 
and the training and testing. 
As part of the inspection requirements within one of the elements, the standard states:
It is the pilot-in-command’s responsibility to ensure that aircraft critical surfaces are 
not contaminated at take-off.239
 237 Transport Canada, SOR/96-433, Canadian Aviation Regulations, section 602.11 (as amended 
25 November 2020).
238 Ibid., Standard 622.11, section 1.0.
239 Ibid., section 7.2. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 117
1.18.3.2.3 Transport Canada Aeronautical Information Manual
The TC AIM provides information and guidance to pilots and other individuals to help them 
operate safely within the aviation environment and in accordance with the regulations. In 
the chapter on Airmanship, section 2.12.2 contains guidance specific to aircraft 
contamination from frost, ice, or snow. It provides the rationale for this guidance:
The reasons for the regulations are straightforward. The degradation in aircraft 
performance and changes in flight characteristics when frozen contaminants are 
present are wide ranging and unpredictable.
240
The TC AIM also clearly restates the clean aircraft concept and the PIC’s role to ensure that 
the concept is adhered to:
It is imperative that takeoff not be attempted in any aircraft unless the pilot-in￾command has determined that all critical components of the aircraft are free of 
frost, ice or snow contamination.241
1.18.3.2.4 Guidelines for Aircraft Ground – Icing Operations
TC also publishes very specific and thorough guidance on certain topics, including ground 
icing operations, for which it publishes Guidelines for Aircraft Ground – Icing Operations. 
The guidance within this document is not mandated by regulation, but rather provides
specific information to help operators develop a GIOP. The foreword states:
It is intended that all of those involved in Ground Icing Operations will find some 
information in this document that will assist them in their understanding of such 
operations.
There are a very large number of variables involved in operating aircraft during 
ground icing conditions. For this reason it is difficult to prescribe a solution for each 
and every situation that may arise. Therefore, this document generally identifies the 
principles at play and it is understood that a large measure of sound judgement will 
be required in many instances to ensure the continuance of safe aircraft operations 
under ground icing conditions.242
The guidance contains information applicable to the operation of aircraft in Canada under 
ground icing conditions, which it defines as:
With due regard to aircraft skin temperature and weather conditions, ground icing 
conditions exist when frost, ice, or snow is adhering or may adhere to the critical 
surfaces of an aircraft.
 240 Transport Canada, TP 14371E (2017-2), Transport Canada Aeronautical Information Manual (TC AIM), AIR —
AIRMANSHIP (12 October 2017), section 2.12.2.
241 Ibid.
242 Transport Canada, TP 14052E, Guidelines for Aircraft Ground Icing Operations, Second Edition (April 2005), 
Foreward [sic]. 

118 | TRANSPORTATION SAFETY BOARD OF CANADA
An approved Ground Icing Program must specify the procedure for identifying 
the existence of ground icing conditions [emphasis added] and the initiation of 
ground icing operations.
Ground Icing Conditions also exist when active frost, frozen or freezing precipitation 
is reported or observed.
243
The document contains very detailed guidance on many related tasks; in section 11.2 
Deicing and Anti-icing Inspection – General, it states:
There have been ground icing accidents associated with the improper inspection of 
high wing turboprop aircraft employed in commercial service. Particularly 
vulnerable are those high wing turbo prop aircraft operated from remote locations 
with minimally equipped facilities. For these types of operations, the pilot is usually 
the final person to perform the pre-take-off inspection. It is often difficult to clearly 
see frozen contaminants from a brief view of the upper wing surface, especially if 
the pilot is balancing on a strut to gain the necessary view. The use of proper 
inspection equipment, such as wing inspection ladders, is highly 
recommended. [emphasis added]244
In section 11.2.3.4 – Traditional methods of conducting a Critical Surface Inspection, it 
states:
It becomes more difficult, during night operations, during conditions of poor lighting 
and during inclement weather when visibility is substantially reduced, to achieve 
consistent results with visual inspections.245
Because it can be difficult for flight crews to visually check the aircraft’s critical surfaces 
immediately before takeoff, section 11.2.5.2 provides guidance for using representative 
surfaces that have been approved by the manufacturer specifically for this purpose:
a) Particularly for large aircraft where very limited portions of the aircraft can be 
seen from inside, approved representative surfaces may be used to judge the 
condition of the aircraft’s critical surfaces during ground icing conditions […]
b) An aircraft’s Representative Surface is a portion of the aircraft that can be 
readily and clearly observed by flight crew from inside the aircraft and is used to 
judge whether or not the surface has become contaminated.246
1.18.3.3 Direction from Avions de Transport Régional
The aircraft’s manufacturer, Avions de Transport Régional (ATR), provides guidance to 
operators regarding operations in icing conditions in several manuals, including the AFM
and FCOM, as well as in informal documents, such as brochures.
1.18.3.3.1 Airplane Flight Manual
The ATR 42 AFM defines icing conditions in the limitations section:
 243 Ibid., Chapter 18.
244 Ibid., section 11.2.1.
245 Ibid., section 11.2.3.4.
246 Ibid., section 11.2.5.2. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 119
• Atmospheric icing conditions exist when :
- OAT [outside air temperature] on the ground and for take-off is at or below 
10° C or when TAT [total air temperature] in flight is at or below 10°C,
- and visible moisture in any form is present (such as clouds, fog with 
visibility of less than one mile, rain, snow, sleet and ice crystals).
• Ground Icing conditions exist when :
- OAT on the ground is at or below 10°C,
- and surface snow, standing water or slush is present on the ramps, taxiways 
and runways.247
It also reiterates: 
Take-off is prohibited when frost, snow or ice is adhering to the wings, control 
surfaces or propellers.248
In this manual, ATR defines ground icing conditions differently than the other guidance 
provided in this report. Other guidance refers to ground icing conditions existing whenever
frost, ice, or snow is adhering or may adhere to the critical surfaces of an aircraft that is on 
the ground, whereas ATR’s definition refers to aircraft icing conditions that result from 
contamination on the ground.
1.18.3.3.2 Flight Crew Operating Manual
The FCOM includes more detailed information and procedures for flight crews to follow in 
order to operate in accordance with the AFM.
In the adverse weather section, it clarifies when icing procedures must be used:
Even small quantities of ice accretions, which may be difficult to detect visually, may 
be sufficient to affect the aerodynamic efficiency of an airfoil. For this reason, ALL 
ANTI ICING PROCEDURES and SPEED LIMITATIONS MUST BE COMPLIED WITH as 
soon as and as long as ICING CONDITIONS are met and even before ice accretion 
actually takes place.
249
The FCOM also provides detailed information regarding how to complete an exterior safety 
inspection. During icing conditions, it adds the following guidance:
EXTERIOR SAFETY INSPECTION
• Perform normal exterior inspection.
• Check that the following items are free of frost, ice or snow. De ice as necessary :
– engine inlets, cowling and drains, propellers
– pack inlets
 247 Avions de Transport Régional, ATR 42 Airplane Flight Manual, Revision no. 24 (July 2013), Chapter 02, 
section 06, p. 1.
248 Ibid.
249 Avions de Transport Régional, ATR 42 Flight Crew Operating Manual, Revision no. 41 (August 2015), Part 2, 
Chapter 02, section 08, p. 2. 

120 | TRANSPORTATION SAFETY BOARD OF CANADA
– landing gear assemblies, landing gear doors
– drains, pitot and static vents, angle of attack sensors
– fuel tank vents
– all external surfaces (fuselage, wings, tailplane, vertical and horizontal 
stabilizers, control surfaces).
CAUTION: Wing, tailplane, vertical and horizontal stabilizers, all control surfaces 
and flaps should be clear of snow, frost and ice before take off.
250
1.18.3.3.3 Cold Weather Operations brochure
ATR published a Cold Weather Operations brochure in March 2011 to provide operators 
with a thorough understanding of ATR aircraft operations in cold weather conditions. The 
brochure covers topics such as icing phenomena, icing prevention or control systems, 
performance loss, and applicable procedures.
Section 2 of the brochure describes many different methods through which ice may 
accumulate on an aircraft. The only method mentioned in this section that involves icing 
accumulation in the absence of visible moisture (the type of ice accumulation that occurred 
while on the ground at CZFD) was the formation of hoar frost:
On ground
Anticyclonic conditions in winter, with clear night skies and little wind can cause a 
sharp drop in ground temperature, which leads to formation of hoar frost on an 
aircraft parked outside overnight.251
The brochure echoes the icing inspection guidance from the FCOM, and also contains 
significant guidance on the methods to de-ice an ATR aircraft. The brochure does not,
however, mention the minimum equipment required to inspect or de-ice high surfaces, such 
as the wing or horizontal tail.
1.18.3.4 Direction from West Wind
1.18.3.4.1 West Wind Aviation 705 Operations Manual
The overarching company guidance for all of West Wind’s Subpart 705 operations are 
contained within the West Wind Aviation 705 Operations Manual. 
The manual contains significant guidance on the potential hazards that exist when 
operating in conditions conducive to airframe icing.
With regard to critical surface contamination, the manual sets out the following definitions:
“Critical surfaces” — the wings, control surfaces, propellers, horizontal 
stabilizers, vertical stabilizers, or any other stabilizing surface of an aircraft.
 250 Ibid., pp. 16–17.
251 Avions de Transport Régional, Cold Weather Operations: Be Prepared for Icing [brochure] (March 2011), 
Chapter A, subsection A.2.4.1. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 121
“Critical surface inspection” — a pre-flight and for some aeroplanes a tactile 
inspection of critical surfaces conducted by a qualified person to determine 
if they are contaminated by frost, ice, or snow. Under ground icing 
conditions, this inspection is mandatory.
“Pre-take-off Contamination Inspection” — is an inspection conducted by a 
qualified person, immediately prior to take-off, to determine if an aircraft's 
critical surfaces are contaminated by frost, ice, or snow. This inspection is 
mandatory.252
The manual also further explains the hazard of surface contamination, who should ensure
that the aircraft critical surfaces are clean, and what to do if they are not:
A very small amount of surface contamination by ice, frost, or snow can disrupt air 
flow over the lift and control surfaces of an aircraft. This can result in:
• severe lift loss;
• increased drag; and,
• impaired maneuverability.
Ice can also interfere with the movement of control surfaces or add significantly to 
aircraft weight as well as block critical aircraft sensors. There is no such thing as an 
insignificant amount of ice.
When existing weather conditions are favorable to contamination formation, the 
Captain has the responsibility to ensure that the aircraft is inspected prior to takeoff 
to determine whether any frost, ice, or snow is adhering to any of its critical surfaces
Note: All contamination must be removed prior to departure. If a clean aircraft for 
departure cannot be assured, the only acceptable alternative is to cancel or postpone 
the flight until conditions are acceptable and the aircraft is free of contaminates.
253
1.18.3.4.2 West Wind ATR 42 standard operating procedures
West Wind flight crew policies and procedures specific to the ATR 42 are provided in the 
West Wind ATR 42 SOPs, which are derived from the AFM, FCOM, and ATR 42 Quick 
Reference Handbook.
SOPs and checklists provide procedural guidance to pilots for the operation of the aircraft. 
They assist with decision making and establishing shared mental models between flight 
crew members, as well as providing them with pre-determined solutions to various 
situations, whether the situations are associated with normal, abnormal, or emergency 
operations.
The West Wind ATR 42 SOPs specify the responsibilities of crew members regarding 
reporting and removal of aircraft surface contamination. These are contained in a section 
focusing on before engine start:
2.10 Aircraft Icing Operations – Before Engine Start
 252 West Wind, West Wind Aviation 705 Operations Manual, Amendment 34 (21 December 2015), Chapter 5, 
section 16, p. 31.
253 Ibid., p. 32 

122 | TRANSPORTATION SAFETY BOARD OF CANADA
Although the Captain is responsible to ensure that the aircraft is free from surface 
contamination prior to the start of an engine with the intent to fly the aircraft, any 
crew member who becomes aware of surface contamination has the responsibility 
to advise the Captain of its existence. If Surface contamination is detected it shall be 
removed prior to departure as outlined in the procedures contained in the West 
Wind Aviation Ground Icing Operations Program (GOIP) [sic].
254
They are also in a section focusing on the period before takeoff:
3.8 Aircraft Icing Operations – Taxi
Regardless of any previous actions taken to inspect for or remove frost, ice, or snow, 
if the crew suspects that such contamination is present, the following inspections 
shall be made immediately prior to take-off:
The PF and PNF shall each visually inspect the representative surface that is visible 
from their respective pilot seats.
If the Captain deems it appropriate, the PNF shall carry out an external inspection of 
the critical surfaces.
Should any frost, ice, or snow be found to be adhering to critical surfaces, the 
aircraft shall not take-off. Rather arrangements shall be made to de-ice the 
aircraft.255
The SOPs also include division of duties and standard calls made by the PF and PNF; these 
include standard calls associated with all phases of flight. Checklists associated with normal 
and abnormal operations are in a challenge-and-response format, and the SOPs provide 
greater detail about what is supposed to be done during these checks. 
For example, the fifth item in the BEFORE TAKE OFF CHECK simply states the challenge as 
“Flight Controls” and the Captain’s response as “Check;” however, the SOPs provide greater 
detail:
Flight Controls .............................................Captain ........................................................... Check 
F/O moves elevator up 1, down 2, left 3 (check left spoiler (captain) and spoiler light
(F/O)), right 4 (check right spoiler (F/O) and spoiler light (Capt)), and Captain 
checks rudders left 5 and right 6 full travel.256
This check not only ensures that the control surfaces are performing correctly, but it also 
serves as the final check to ensure that the representative surfaces (the spoilers, in the case 
of the ATR 42) are free from surface contamination.
 254 West Wind, ATR42 SOP (17 December 2016), Chapter 2, section 2.10, p. 49.
255 Ibid., Chapter 3, section 3.8, p. 57.
256 Ibid., Chapter 4, section 4.2, p. 60. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 123
1.18.3.4.3 West Wind ground icing operations program
General
As required by regulation, West Wind has a GIOP in place, the details of which are contained 
in the West Wind GIOP manual. The GIOP manual outlines the company’s policy, as well as 
the program and elements of the program, and applies to all company operations during 
ground icing conditions. 
The policy257 mirrors the clean aircraft concept, in that its intent is to ensure that
No flight shall commence where any frost, ice or snow is adhering to any critical 
surface of the aircraft.
The program elements include the management plan, aircraft procedures (including icing 
hazards, de-icing / anti-icing, and holdover times), inspection procedures, and training.
The ground icing program is required by regulation for all operations in ground icing 
conditions. With regard to this term, the GIOP manual contains exactly the same definition 
as TC’s Guidelines for Aircraft Ground Icing Operations:
Z. GROUND ICING CONDITIONS
With due regard to aircraft skin temperature and weather conditions, ground icing 
conditions exist when frost, ice, or snow is adhering or may adhere to the critical 
surfaces of an aircraft. An approved Ground Icing Program must specify the 
procedure for identifying the existence of ground icing conditions and the 
initiation of ground icing operations. [emphasis added] Ground Icing Conditions 
also exist when active frost, frozen or freezing precipitation is reported or 
observed.
258
Aircraft procedures 
The chapter of the GIOP manual on aircraft procedures lists many of the potential sources of 
ice, snow, frost, or other contaminants. With regard to conditions similar to those prevailing 
the evening of the occurrence flight, this section makes reference to the following 2 hazards:
5) Frost may form on aircraft surfaces on clear nights or conditions of fog, 
particularly when ambient temperatures are near 0°C. […]
10) Ice may remain on aircraft after flight in icing conditions where in-flight de-icing 
equipment has not been sufficient for complete removal or in areas where no 
onboard equipment is installed.259
Although the GIOP manual details many of the hazards involved with icing and various 
sources of ice, snow, or frost, it does not specify any explicit procedure for identifying 
ground icing conditions, even though TC’s Guidelines for Aircraft Ground Icing Operations
and the GIOP manual itself state that it must. 
 257 West Wind, Ground Icing Operations Program, Re-Issue (February 2016), Chapter 1, p. 9.
258 Ibid., Chapter 2, p. 5.
259 Ibid., Chapter 5, p. 2. 

124 | TRANSPORTATION SAFETY BOARD OF CANADA
The aircraft procedures section also describes the methods, equipment, and supplies 
required to de-ice or anti-ice an aircraft. The manual details how to manually remove snow 
or slush using tools such as brooms, squeegees, rope, or cloth strips. It also describes how to 
remove ice using a heated de-ice fluid that is sprayed under pressure. The manual specifies 
the types of fluid, and the method to use them, but does not specify what type of spray 
equipment is required or the quantity of fluid needed.
Inspection procedures
Chapter 7 of the GIOP manual lays out the procedure for inspecting the aircraft’s critical 
surfaces. The inspections are split into 2 basic types: critical surfaces inspections (while 
stationary) and pre-takeoff contamination inspection (immediately before takeoff).
A. CRITICAL SURFACE INSPECTIONS
Aircraft Acceptance:
During the pre-flight inspection and station stop walkarounds, inspect the aircraft 
giving special attention to the areas and surfaces detailed in Section 5 [of chapter 7]. 
Ensure the aircraft is inspected in lighting conditions which will provide for 
adequate visual inspection.
260
The referenced section includes guidance to pay special attention to certain areas and 
surfaces, such as landing gear, engine intakes, and flying control surfaces, and makes
specific mention of T-Tails / Elevated Control Surfaces:
The height of a T-Tail or other elevated control surface presents special difficulty in 
ensuring adequate anti-ice / de-ice fluid application and protection.
In many cases the entire tail surface is obscured from flightcrew vision at take-off; 
pre-flight inspection must be carried out immediately prior to the take-off roll.
Special equipment, such as lifts and/or ladders will be required to ensure 
adequate contaminant removal. [emphasis added]261
If this equipment is unavailable or inadequate, the manual describes what actions 
employees should take:
Operations Personnel are required to immediately report any deficiency in 
equipment or procedure relating to the detection, inspection or removal of aircraft 
surface contamination. Such deficiencies are to be reported directly to the Director 
of Flight Operations by SMS report.262
If contamination is identified during the pre-flight inspection, the manual describes the 
following:
Where a pre-flight inspection or station stop walkaround reveals the presence of 
critical surface contamination the aircraft Pilot-in-Command shall be advised 
 260 Ibid., Chapter 7, p. 3.
261 Ibid., Chapter 5, Section E, p. 19.
262 Ibid., Chapter 1, p. 10. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 125
immediately. The Pilot-in Command shall then inspect the aircraft and order the 
appropriate elements of the Ground Icing Operations Program into effect to remove 
the contamination.263
Once the aircraft has been inspected during the pre-flight or station stop walkaround, and 
either found to be clear of contamination or de-iced to remove contamination, another “last 
chance” inspection is required before takeoff:
B. PRE-TAKE-OFF CONTAMINATION INSPECTION
[…] the inspection is required immediately prior to the application of take-off power 
and requires that a Representative Surface be used in the inspection process. This 
inspection is commonly referred to as the Last Chance Inspection.264
The representative surfaces are designated for each aircraft type:
A. REPRESENTATIVE SURFACE – ATR 42
The representative surface designated for the ATR 42 aircraft is the Right and Left 
Spoiler. The Spoilers are painted Black and Yellow hashed pattern and are visible 
from the cockpit in the extended position.265
The manual describes the communication required during the conduct of the last chance 
inspections:
F. PRE-TAKE OFF (LAST CHANCE) INSPECTIONS – REPORTING
 263 Ibid., Chapter 7, Section 6(A), p. 14.
264 Ibid., Chapter 7, Section 2(B), p. 2.
265 Ibid., Chapter 7, Section 4, pp. 4–5. 

126 | TRANSPORTATION SAFETY BOARD OF CANADA
This inspection will be accomplished using a “Call and Response” method when 
trained crew members complete individual elements of the inspection.
When the Pilot-in-Command calls for the inspection at the runway threshold, crew 
members are to communicate clearly the result of the inspection. ie: "My wing is 
clean" or "I have snow on my wing".
Under no circumstances are vague or ambiguous terms to be used.266
Training
The GIOP manual also describes the training in place to meet the requirements of the 
regulations,
267 and relevant standards.
268
West Wind provided its pilots with an online initial and recurrent training program that 
covers the hazards of icing and the policies regarding the clean aircraft concept. The 
program did not include any specific information about the equipment required to inspect 
or de-ice an aircraft the size of an ATR 42, nor was this information required by regulation.
1.18.3.5 Equipment at Fond-du-Lac Airport
The ATR 42 aircraft’s main critical surfaces, the wing and horizontal stabilizer, are 3.76 m
and 7.75 m above the ground, respectively. 
At CZFD, there was no equipment available that would enable someone to visually inspect
the top portion of an ATR 42’s critical surfaces, given their height, nor to reach them to 
apply de-icing fluid. The only equipment available were 2 ladders, 1 approximately 3.44 m
and the other 1.83 m (Figure 37). The 3.44 m ladder had a maximum standing height of 
2.77 m.
 266 Ibid., Chapter 7, Section 6(F), p. 17.
267 Transport Canada, SOR/96-433, Canadian Aviation Regulations (CARs), section 602.11 and 
clause 705.124(2)(a)(4)(D).
268 Transport Canada, Operating and Flight Rules Standards, section 622.11, and Commercial Air Services 
Standards, subsection 725.124(23). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 127
Figure 37. Photos showing ladders available at the Fond-du-Lac Airport terminal (Source: TSB)
West Wind’s de-icing spray equipment at CZFD consisted of a hand-held spray system with 
a small-capacity heated fluid reservoir and 20 L container of additional type I fluid.
269
Another air operator also had a small (20 L), heated hand-held spray system in the terminal 
building that was available to West Wind personnel on request (Figure 38). 
Published de-icing standards recommend that the fluid quantity required to de-ice an 
aircraft is 1 L/m2 of aircraft surface. In the case of an ATR 42 aircraft, more than 66 L would 
be required.
270
1.18.3.6 Actual inspection at 
Fond-du-Lac Airport
Once the passengers had 
boarded the aircraft for 
departure, the FO walked 
around the aircraft to 
conduct a visual external 
inspection, as required in 
ground icing conditions.
Although it was dark and 
there was limited lighting 
on the apron, the FO 
observed contamination 
on the nose of the aircraft
and some residual ice on 
 269 “Aircraft deicing fluids are typically ethylene glycol, diethylene glycol or propylene glycol based while recent 
innovation has led to the commercialization of non-glycol based fluid. Most of these fluids contain corrosion 
inhibitors, surfactants (wetting agents) and dyes. These fluids are formulated to assist in removing ice, snow 
and frost from the exterior surfaces of aircraft and also provide a short period of anti-icing protection. Type I 
fluids are typically used for the deicing function.” (Source: Transport Canada, TP 14052E, Guidelines for 
Aircraft Ground Icing Operations, Second Edition [April 2005], Chapter 8, section 8.1.2.)
270 SAE International, Aerospace Standard AS6285 – Aircraft Ground Deicing/Anti-Icing Processes (Issued 2016-
08), section 8.8, Table 1, p. 34.
Figure 38. De-icing equipment available at Fond-du-Lac Airport: West 
Wind’s equipment on left, another operator's equipment on right 
(Source: TSB) 

128 | TRANSPORTATION SAFETY BOARD OF CANADA
the leading edges of the wings, engine intakes, and on the vertical stabilizer. The FO also 
noticed ice hanging from power lines near the terminal, and on nearby structures and 
vegetation. The external inspection ended with the FO visually examining the left wing from 
the top of the airstair door on the left side of the rear cabin before returning to the cockpit.
The FO did not request or make use of the available, albeit inadequate, ladders.
Although surface contamination was identified during the inspection, the FO did not request 
de-icing equipment or attempt to use the equipment himself. The FO informed the captain 
about the ice that he noticed on the power lines, and that this ice was on the aircraft as well. 
The captain responded in a manner that suggested he was not concerned, and, shortly 
afterward, requested the before-start checklist.
Once on the threshold, immediately before takeoff, the crew completed the last portion of 
the before-takeoff checklist, which included the “last-chance inspection” as part of the flight 
control check. The captain stated that he had the representative surface (the left spoiler) in 
sight. The FO responded that had the right spoiler in sight, but just barely. 
1.18.3.7 Similar occurrences
The problem of aircraft departing with frost, ice, or snow adhering to their critical surfaces 
is not a new one, nor is the problem isolated to Canada’s remote northern airports. The
investigation gathered a list of similar occurrences in Canada (Appendix J) and worldwide
(Appendix K) in which contaminants on critical surfaces of aircraft during takeoff was a 
factor.
1.18.4 TSB Watchlist
The TSB Watchlist identifies key safety issues that need to be addressed to make Canada’s 
transportation system even safer. 
Safety management and regulatory surveillance are Watchlist 2020 issues. 
As this occurrence demonstrates, some companies consider safety to be adequate as long as 
they are in compliance with regulatory requirements, but regulations alone cannot predict 
all risks unique to a particular operation. That is why the TSB has repeatedly emphasized 
the advantages of SMS, an internationally recognized framework that allows companies to 
manage risk effectively and make operations safer.
ACTIONS REQUIRED
Regulatory surveillance will remain on the Watchlist for the air transportation sector until TC 
demonstrates, through surveillance activity assessments, that the new surveillance procedures are 
identifying and rectifying non-compliances, and that TC is ensuring that a company returns to 
compliance in a timely fashion and is able to manage the safety of its operations.
ACTIONS REQUIRED
Safety management will remain on the Watchlist for the air transportation sector until:
• TC implements regulations requiring all commercial operators to have formal safety management 
processes; and 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 129
1.19 Useful or effective investigation techniques
1.19.1 TSB pilot survey
1.19.1.1 Objective
Early in this investigation, it became clear that more information was needed to determine 
whether the underlying factors identified in this occurrence were present elsewhere in the 
Canadian commercial aviation industry.
To assess the risks involved with winter operations at remote northern airports, and 
specifically the risk posed by aircraft taking off with frost, ice, or snow adhering to critical 
surfaces, the TSB decided to reach out to pilots who were directly exposed to operations in 
remote airports throughout Canada through an online data collection method, to quickly 
and efficiently reach a large number of these pilots. This took the form of an online 
questionnaire for commercial pilots employed by air operators operating at remote 
northern airports under Part VI or Part VII of the CARs. The online platform permitted 
anonymous collection of responses and stored the responses on servers located in Canada.
1.19.1.2 Participants
The TSB emailed bilingual pilot invitations to 83 Canadian commercial air operators that, on 
31 May 2018, operated under subparts 604, 702, 703, 704, and 705 of the CARs.271 The 
selected operators were those likely to have flights taking off from the airports shown in
Figure 39. Large national airline operators that operate primarily from airports in southern 
Canada were deliberately excluded.
 271 Transport Canada, Operator List Search [database], at http://wwwapps.tc.gc.ca/saf-sec-sur/2/CAS￾SAC/olsrlel.aspx?lang=eng (last accessed 15 February 2021).
• Transportation operators that do have an SMS demonstrate to TC that it is working—that hazards 
are being identified and effective risk-mitigation measures are being implemented. 

130 | TRANSPORTATION SAFETY BOARD OF CANADA
Figure 39. Remote northern airports (Source: Office of the Auditor General, 2017 Spring Reports, 
Report 6—Civil Aviation Infrastructure in the North—Transport Canada)
Invitations were also sent to several pilot unions representing pilots employed by the 
selected operators, and an aviation industry association of air operators.
All organizations that received the invitation had access to the questionnaire and could
choose whether to forward the invitation to their pilots. Questionnaire participation was 
both voluntary and anonymous; the questionnaire did not request location information or 
operator identities.
The selected air operators that provided staffing information employed 2768 pilots. Air 
operators that did not provide pilot numbers are estimated to employ an additional 
500 pilots. It is not known how many pilots received invitations forwarded by their 
operator or union. Additionally, because the invitation and hyperlink to the questionnaire 
web page were widely distributed, and redistributable, it is possible and likely that 
additional pilots outside the intended sampling frame had access to the questionnaire.
1.19.1.3 Questionnaire
The questionnaire (Appendix L) contained 24 items and was available online from 23 July to 
31 August 2018. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 131
Most questions were phrased as statements, and respondents were asked to rate their 
experiences on a 5-point Likert scale (Never, Rarely, Sometimes, Usually, or Always; or 
Strongly disagree, Disagree, Neither agree nor disagree, Agree, or Strongly Agree). A “Does 
not apply” option was also available. 
Statements and other questions explored the following issues:
• Access to ground equipment to inspect aircraft for contamination, de-icing, and anti￾icing at remote airports 
• Situations in which a flight crew may decide to divert to an alternate airport
• A crew’s ability to have their aircraft de-iced and anti-iced effectively at remote 
airports
• Whether the respondent’s employer had a company ground icing program
• Pilots’ self-assessed knowledge of the effects of contaminated critical surfaces
• Whether, in the past 5 years, respondents had witnessed other pilots taking off with 
contaminated critical surfaces
The remaining questions collected information about the pilots and their industry 
experience:
• Operations category
• Primary aircraft
• Type of pilot licence 
• Total flight time
• Total PIC flight time
• Number of years employed as a pilot
• Number of winter seasons in which they have flown to remote airports
• Number of years with current employer
• Primary role with current operator
• Crew position on aircraft they fly most frequently
• Total flight time on aircraft they fly most frequently
• PIC time on aircraft they fly most frequently
1.19.1.4 Responses
The ability to exit the questionnaire and continue progress at a later time was disabled 
because this option required storage of identifying “cookies,” and some respondents could 
be using a shared computer to respond to the questionnaire. Consequently, upon returning 
to the questionnaire page to complete it, respondents were forced to start again. Likely for 
that reason, many respondents entered duplicate responses: once in an incomplete 
response, and again in a completed response. To avoid including duplicate responses, only 
completed responses were used in the analysis. 

132 | TRANSPORTATION SAFETY BOARD OF CANADA
The questionnaire welcome page was opened 1022 times: 872 times in English and 
150 times in French. The welcome page explained the objectives and terms of the 
questionnaire, and concluded with an agreement button. Of the 1022 visitors, 110 opened 
the welcome page, but did not continue past the agreement button, and 912 continued by 
clicking the agreement button.
Not every visitor completed the questionnaire; there were 257 incomplete responses: 
228 in English and 29 in French.
Thus, there were 655 complete responses: 551 in English and 104 in French.
1.19.1.5 Key takeaways
Descriptive information about the questions, and the statistics collected from the 
655 complete responses, are summarized in Appendix M; however, the key takeaways are 
detailed in the following table (Table 6).
Table 6. Pilot survey responses (n=655)
Question Never Rarely Sometimes Usually Always
Does 
not 
apply
Yes No
When I am at a remote 
airport, I have access to 
ground equipment that 
enables effective 
inspection of all of the 
aircraft’s critical surfaces 
for contamination.
26 177 174 178 96 4 n/a n/a
When I am at a remote 
airport, I have access to 
ground equipment that 
enables adequate 
de‑icing of the aircraft’s 
critical surfaces before 
takeoff.
41 191 177 165 77 4 n/a n/a
When I am at a remote 
airport, I have access to 
ground equipment that 
enables adequate anti￾icing of the aircraft’s 
critical surfaces before 
takeoff.
207 206 98 83 45 16 n/a n/a
I am able to have my 
aircraft de-iced 
effectively at remote 
airports.
37 216 152 180 65 5 n/a n/a
I am able to have my 
aircraft anti-iced 
effectively at remote 
airports.
231 213 89 68 29 25 n/a n/a 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 133
In the past 5 years, I have 
seen pilots take off with 
contaminated critical 
surfaces.
n/a n/a n/a n/a n/a n/a 483 172
1.19.1.6 Recommendations issued following the survey
1.19.1.6.1 Access to adequate equipment
The responses received to several questions showed that operations at these remote 
airports were routinely affected by the unavailability and inadequacy of equipment to 
inspect, de-ice, or anti-ice aircraft.
Many survey respondents answered that they rarely have access to adequate inspection and 
de-icing equipment. The unavailability of adequate equipment is a significant underlying 
factor that prevents pilots from being able to conduct a proper pre-flight inspection for 
contaminants and from de-icing a contaminated aircraft. Only 37% of respondents reported 
that they can have their aircraft de-iced effectively at remote airports.
Most survey respondents answered that they rarely have access to adequate anti-icing 
equipment. Only 15% of respondents reported that they can have their aircraft anti-iced 
effectively at remote northern airports. Where anti-icing is not available, flights operating in 
active ground icing conditions can experience type I fluid failure272 because of the short 
amount of time that type I fluids are able to absorb frozen precipitation.
As demonstrated by this occurrence, when adequate inspection, de-icing, and anti-icing 
equipment or services are not available at remote airports, this may influence a flight crew’s 
decision to depart and ultimately result in aircraft being operated with contaminated 
surfaces. Similar occurrences investigated by the TSB and other agencies over the past 
36 years (Appendices J and K) indicate that departures with contaminated surfaces still 
occur, occasionally with catastrophic consequences. Canada is substantially exposed to the 
risk of such accidents, given its large and diverse fleet of aircraft operating at remote 
northern airports where icing conditions are present.
The combined probability and severity of this safety deficiency poses a high risk to aviation 
safety. The risk likely varies from airport to airport, depending somewhat on the frequency 
of operations. Identifying high-risk locations for immediate mitigation can quickly reduce 
the likelihood of aircraft taking off with frost, ice, or snow adhering to any critical surface at 
those locations.
TC, air operators, and airport authorities have the capacity to identify high‑risk locations, 
analyze them for hazards and risks, and take mitigating action.
 272 “A fluid is considered failed when it is no longer able to absorb frozen precipitation. Under these 
circumstances it must be assumed that the contamination is adhering to the critical surfaces.” (Source: 
Transport Canada, TP 10643E, When in Doubt...: Small and Large Aircraft – Aircraft Critical Surface 
Contamination Training For Aircrew and Groundcrew, 7th Edition [December 2004], Chapter 4, section 88, 
p. 54.) 

134 | TRANSPORTATION SAFETY BOARD OF CANADA
Therefore, in December 2018, the Board issued TSB Recommendation A18-02, which called 
for Transport Canada to collaborate with air operators and airport authorities to take action 
to ensure that the proper equipment is available to reduce the likelihood of aircraft taking 
off with contaminated critical surfaces. See section 4.1.1.1 TSB Recommendation A18-02 on 
access to adequate equipment for further details.
1.19.1.6.2 Compliance with the clean aircraft concept 
The most notable information received from the survey showed that, in the past 5 years, 
74% of pilots have seen aircraft take off with contaminated surfaces, in contravention of 
regulations and the clean aircraft concept. This majority indicates that the issue is systemic, 
rather than isolated to a small number of operators or a select few locations. 
There are many defences in place to ensure the clean aircraft concept is followed, such as 
regulations, company operating manuals, and SOPs. However, all of these defences rely 
singularly on flight crew compliance. As seen in this occurrence, when a single-point 
compliance adaptation is made, aircraft may depart with contaminated surfaces, despite 
several adequate administrative defences in place. 
To mitigate this hazard, TC and air operators must take urgent action to ensure better 
compliance.
The regulator and other organizations can audit equipment, policies, training, and 
operations. Air operators could take similar steps or make procedural changes such as 
incorporating questions in before-start and before-takeoff checklists, with a requirement 
for a clean aircraft or a mitigation response from the PIC. 
Accidents related to contaminated aircraft will continue to occur until the industry and the 
regulator approach the issue as systemic and take action to eliminate underlying factors 
that can negatively affect pilot compliance. 
Therefore, in December 2018, the Board issued TSB Recommendation A18-03, which called 
for Transport Canada and air operators to take action to increase compliance with 
CAR 602.11(2) and reduce the likelihood of aircraft taking off with contaminated critical 
surfaces. See section 4.1.1.2 TSB Recommendation A18-03 on compliance with the clean 
aircraft concept for further details. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 135
2.0 ANALYSIS
This accident involved an aircraft that departed with contamination on its critical surfaces, 
which resulted in a loss of control and collision with terrain that ultimately led to 1 person 
being fatally injured.
This analysis will focus on those factors that caused or contributed to the accident, 
including:
• How ice accumulated on the aircraft
• Why the crew were not aware of the extent of the ice
• Why the ice that was known was not removed before departure
• Which factors influenced the decision to depart
• Why the flight crew lost control of the aircraft during the initial climb
• How and why the airframe suffered significant damage during the impact 
• Why the occupants received the severity of injuries that they did
Additionally, this section will analyze several other risks that were not found to be a factor 
in this occurrence but could have adverse consequences in future occurrences. These risks
include issues related to guidance material, survivability, organizational safety, and 
regulatory oversight. 
2.1 Weather and icing
2.1.1 Flight planning
To prepare for the day’s flights, the flight crew, along with the dispatcher, reviewed the 
latest aerodrome routine meteorological reports (METARs) and the forecast weather, 
including the aerodrome forecasts (TAFs) and the graphic area forecasts (GFAs).
The GFAs forecast moderate icing in the area of Fond-du-Lac, in clouds, between 2000 and 
8000 feet. The forecast also predicted localized moderate icing from the surface to 2000 feet
while in the presence of freezing drizzle. However, the GFA did not predict any icing outside 
of clouds or precipitation from conditions such as freezing fog.
Similarly, the TAFs for Stony Rapids Airport (CYSF), the closest reporting station to Fond￾du-Lac Airport (CZFD), forecast conditions throughout the day that included visibilities as 
low as 2 statute miles (SM) in light snow and occasional mist, but did not forecast any type 
of icing such as freezing rain, freezing drizzle, or freezing fog. 
Weather conditions recorded at CYSF earlier on the occurrence day included icing (ice 
detected on the probe) without any form of precipitation and without visibilities below 
2 SM. Icing was also recorded shortly before the occurrence, with the presence of only light 
snow. 
Weather forecasting guidance is provided to weather specialists in Canada in the Manual of 
Standards and Procedures for Aviation Forecasts. The guidance in this manual, and in similar  

136 | TRANSPORTATION SAFETY BOARD OF CANADA
U.S. and international manuals, does not allow for the forecasting of icing in TAFs unless 
there is also rain (freezing rain), drizzle (freezing drizzle), or fog (freezing fog). Because fog 
is only reportable when the visibility is less than ⅝ SM, there is no provision for the 
reporting of icing conditions when the source of the icing is mist, in visibilities between 
⅝ SM and 6 SM. 
The phenomenon of ground ice accumulation in the absence of precipitation or fog, and the 
conditions that can cause it, are relatively complex and may not be widely understood. 
Finding as to risk
If weather forecasting guidance does not allow for the forecasting of icing that can occur in 
the absence of precipitation or fog, there is an increased risk that pilots will not have 
advance warning of foreseeable ground icing conditions. 
Although the TAFs that the crew and dispatcher reviewed did not contain any forecast icing, 
the GFAs did contain expected localized ground icing as a result of freezing drizzle in the 
area of several of the intended stops of West Wind Aviation L.P. (West Wind) flight 282
(WEW282). Although freezing drizzle was not observed by the crew while the aircraft was 
on the ground at CZFD, the crew of WEW282 and the dispatcher were aware, at the time of 
planning, of the possibility.
Finding as to causes and contributing factors
Although both the flight crew and the dispatcher were aware of the forecast ground icing, 
the decision was made to continue with the day’s planned route to several remote airports 
that had insufficient de-icing facilities. 
The acceptance of this plan indicates that the dispatcher and flight crew assessed that the 
forecast of icing conditions was not sufficient to warrant cancelling any of the planned 
stopovers. 
2.1.2 Icing on approach
Following departure from Saskatoon/John G. Diefenbaker International Airport (CYXE), the 
occurrence aircraft’s flight to Prince Albert (Glass Field) Airport (CYPA) was uneventful and 
clear of any icing conditions.
After WEW282 departed CYPA for CZFD, the climb and cruise portions of the flight were
also uneventful. While inbound to CZFD, the flight crew obtained a weather update from air 
traffic control for CYSF that indicated light snow and a ceiling at 2300 feet. 
Flight crews flying from CYPA to CZFD normally receive updates for the weather at CYSF, 
which is 42 nautical miles (NM) to the east of CZFD, because there are no weather 
observations available for CZFD. In this instance, the weather conditions at CZFD were 
generally similar to those reported at CYSF but they can vary significantly.
During the aircraft’s descent into CZFD, the flight crew were communicating with 2 flights 
(TW280 and WEW660) going ahead of them into CZFD, and these flights did not report any 
icing conditions. About 15 minutes before landing and before going into cloud, the WEW282  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 137
flight crew heard flight TW280 reporting that the ground was in sight 6 miles from the 
airport. This suggested to the flight crew that the weather conditions were not an issue.
Having flights ahead of WEW282 going into CZFD indirectly reinforced the flight crew’s plan 
to continue with the scheduled flight to CZFD. There is a tendency to continue with the 
original plan unless there is a sufficiently salient cue not to do so. This is consistent with 
plan continuation bias (discussed in section 2.2.4.3 Continuation bias).
On the descent to CZFD, while descending through approximately 7600 feet above sea 
level (ASL), WEW282 encountered light to moderate icing conditions, which persisted until 
the aircraft descended through the cloud base at 2100 feet ASL. In response to this icing 
encounter, the crew of WEW282 activated the aircraft anti-icing and de-icing systems. 
Finding as to causes and contributing factors
Although the aircraft’s ice-protection systems were activated on the approach to CZFD, the 
aircraft’s de-icing boots were not designed to shed all of the ice that can accumulate, and the 
anti-icing systems did not prevent ice accumulation on unprotected surfaces. As a result, 
some residual ice began to accumulate on the aircraft.
Shortly after ice began to accumulate, the flight crew was alerted by an ICING (ice detected) 
light, followed by a DEG PERF (degraded performance) light. The combination and timing of 
these 2 lights indicate that the degraded performance was due to the ice accumulation. 
The crew did not discuss the severity of the icing conditions or the option of diverting to 
another airport. This absence of discussion suggests that each pilot, in isolation, assessed 
that the icing conditions were not severe enough to warrant diverting from CZFD to a 
location where conditions were more favourable.
After the aircraft exited the in-flight icing conditions, the de-icing boots cycled twice more 
before being turned off.
Finding as to causes and contributing factors
Although the flight crew were aware of the ice, there were no handling anomalies noted on 
the approach. Consequently, the crew likely did not assess that the residual ice was severe 
enough to have a significant effect on aircraft performance. Subsequently, without any 
further discussion about the icing, the crew continued the approach and landed at CZFD.
The investigation determined that, despite some further ice removal during the approach, 
shortly before the aircraft landed at CZFD, drag had increased by 28% and the lift 
performance had degraded by 10%, compared with a clean aircraft. This increase in drag 
and decrease in lift performance indicate that the aircraft had significant residual ice 
adhering to its structure upon arrival. 
2.1.3 Icing on the ground
West Wind flight crews that flew into CZFD were generally aware that adequate ground 
inspection and de-icing equipment for the ATR 42 were unavailable. 

138 | TRANSPORTATION SAFETY BOARD OF CANADA
The occurrence flight crew were aware that some residual ice remained on the aircraft 
following the approach and landing at CZFD. The crew were also aware that adequate de￾icing equipment was not available at CZFD. The aircraft remained on the ground at CZFD for 
approximately 48 minutes in active icing conditions. 
2.1.3.1 Weather conditions on the ground in Fond-du-Lac Airport
The weather conditions at the time at CZFD included an overcast ceiling at approximately 
1000 to 1500 feet above ground level (AGL) and light westerly winds; however, no 
observable precipitation was reported. The estimated air temperature was below freezing,
at about −10°C, varying by 1 to 2 °C around the time of the occurrence. The estimated dew 
point ranged within 0 to 2 °C of the air temperature. The visibility was uncertain; however,
patchy areas of visibility between 3 to 6 SM were forecast to exist at the time. Also, freezing 
drizzle was being reported at the Fort Smith Airport (CYSM), Northwest Territories, located 
151 nautical miles to the west of CZFD in the hours before the occurrence. Freezing drizzle 
was not observed when WEW282 was on the ground at CZFD.
The small difference between the air temperature and dew point indicates that the water 
vapour in the air was very close to the saturation limit (90 to 100% relative humidity). 
Since the exact local air temperature and dew point at CZFD are not known, the most likely 
combinations were analyzed to determine the probability of active ground icing conditions. 
Table 7 provides the calculated frost point temperatures for an assumed air temperature of 
−10 °C with possible dew points ranging from −10 to −12 °C:
Table 7. Frost point temperatures
Air 
temperature (°C)
Relative 
humidity
Dew 
point (°C)
Frost 
point (°C)
−10 100% −10 −9
−10 92% −11 −10
−10 85% −12 −11
In the first row, the air temperature is below the frost point; therefore, active frost is 
occurring. Clear ice due to mist is also expected as the air and dew point temperatures are 
the same (100% relative humidity). In the second row, the air and frost point temperatures 
are equal, so, again, active frost is occurring. Mist may not be present because the air 
temperature is above the dew point (92% relative humidity). 
In the final row, the air temperature is above both the frost and dew points. However, in this 
case, as well as the others, a colder aircraft surface could locally chill the air below the 
−10 °C ambient temperature such that frost or mist could form near the surface. In this case,
cooling of only 1 °C could cause active frost conditions or clear ice due to mist.
The prevailing ambient conditions at CZFD consisted of nearly saturated water vapour at a 
sub-zero temperature almost coincident with the dew point and frost point. These 
conditions indicate that there was probably active frost while the aircraft was on the ground  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 139
at CZFD, and that clear ice due to mist was highly likely. Both cause ground icing without 
visible precipitation.
There were significant ice accretions on the structures and vegetation around CZFD before 
the occurrence. These were a result of the active ground icing conditions that prevailed 
before the occurrence, including frost and supercooled mist. These conditions continued 
even after the occurrence, as evidenced by the frozen contamination that formed on the 
wreckage shortly following the crash.
The weather data and ice observations before and after the occurrence indicated that 
ground icing was active and persistent at CZFD for an extended period of time.
2.1.3.2 Ground ice formation without falling precipitation
When any portion of an aircraft surface has a local temperature that is colder than the air 
temperature, the air in contact with the surface will cool by conduction and convection
(Table 8). 
Table 8. Summary of water state transitions
Water state Process Result
Water vapour (gas) Condenses on above-zero surface Dew
Water vapour (gas) Condenses on sub-zero surface Frost
Dew (liquid) Freezes when surface cools below 
zero
Ice
Dew (liquid) Runs down to sub-zero surface and 
freezes
Ice
Ice, frost Melts when surface warms above zero Water, shed ice
Ice, frost Sublimates while sub-zero Water vapour (negligible)
Supercooled water droplets (liquid) Freezes rapidly on contact with sub￾zero surface
Ice
If the air is near water vapour saturation, very little cooling is required before water begins 
to condense from the air. If the aircraft surface is below freezing, the condensation will be in 
the form of frost on the aircraft skin.
If the aircraft surface is above freezing, the condensation will be in the form of liquid water 
drops (dew). As these dew drops run down lower on the aircraft, they may reach surfaces 
that are below freezing, causing the drops to freeze to ice at that location.
Even if the water drops do not immediately encounter a surface below freezing and remain 
as liquid dew drops on the aircraft skin, if the aircraft surfaces continue to cool (such as 
around an engine nacelle after the engine has been shut down), the dew drops can 
eventually freeze to ice once the local surface temperature drops below freezing. Liquid 
water can also freeze to ice during taxi or takeoff.
If supercooled mist droplets have formed in the air, they will rapidly freeze on contact with 
a cold aircraft surface as clear ice. Clear ice can be very difficult to see because it is smooth 
and appears to be the same colour and finish as the aircraft paint beneath it. 

140 | TRANSPORTATION SAFETY BOARD OF CANADA
Such saturated conditions at freezing temperatures273 are active ground icing conditions 
(“active frost”). Although the time for the frost/ice to appear and the rate of growth of 
frost/ice may vary, the threat is the same: the aircraft surfaces can accumulate frozen 
contaminants if not protected by anti-icing fluid.
More so than with visible precipitation, ground icing from frost or clear ice requires
monitoring of weather data, such as temperature and humidity, to determine whether 
active ground icing conditions are present.
2.1.3.3 Aircraft temperature
During the flight to CZFD, the aircraft was in air below −10 °C for about 1 hour 40 minutes, 
of which more than an hour was in air between −35 and −38 °C. Although the actual surface 
temperature distribution of the aircraft when it landed at CZFD is unknown, much of it 
would have been significantly colder than the prevailing frost point. The fuel temperature 
was also likely below the ambient temperature.
2.1.3.4 Ground ice accretion
Once the aircraft was on the ground at CZFD, the moist air in contact with these cold-soaked 
surfaces would have cooled below the frost and dew points. Frost likely began forming on 
the aircraft shortly after it landed at CZFD. The frost deposition rate would have varied over 
the aircraft, being greater on surfaces that were coldest or already contaminated as a result 
of in-flight ice accretion.274 Research sponsored by Transport Canada (TC) has shown that 
frost normally forms in such conditions.275 The occurrence aircraft had no de-icing or anti￾icing fluid applied and was exposed for about 48 minutes. 
If mist or freezing drizzle occurred at the CZFD apron area at any time while the aircraft was 
on the ground, the supercooled droplets would have frozen instantly on contact with the 
aircraft. Although these surfaces would have begun to warm toward the ambient air 
temperature during the time on the ground, any ice or frost already formed would not have 
melted as long as they remained below 0 °C.
The aircraft almost certainly accreted frost on the coldest and/or ice-contaminated surfaces 
shortly after it arrived at CZFD and throughout the time on the ground. Clear ice may also 
have formed from supercooled mist droplets that froze on contact with sub-zero surfaces. If 
 273 “Freezing temperatures” may occur with ambient temperature above 0 °C. The frost point is higher than the 
dew point, and an aircraft can be colder than the air temperature (by cold-soaking, radiational cooling, etc.). 
Therefore, freezing could occur even at ambient temperatures above 0 °C.
274 Existing ice is a prime nucleation site on which new ice crystals can form. White-painted aluminum, 
composite, and honeycomb-backed surfaces have the highest deposition rates. (Source: Transport Canada, 
TP 13665E, Snow Weather Data Evaluation (1995–2000) [January 2000].)
275 Transport Canada, TP 15158E, Aircraft Ground Icing General Research Activities During the 2010-2011 Winter
(July 2012). This publication contains numerous natural frost test results for dry white painted aluminum test 
panels representative of aircraft surfaces, at comparable air temperatures to this occurrence yet with less 
humidity, and all produced frost. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 141
clear ice had formed, it would have been difficult for the crew to detect its presence during 
the time on the ground at CZFD.
2.1.3.5 Interaction with residual ice
The aircraft accumulated ice that could not be shed in flight before it landed at CZFD. 
Several processes could have changed both the shape and distribution of the residual in￾flight ice on the airframe. These would have yielded different aerodynamic effects during 
the takeoff from CZFD than those encountered during the descent and landing. 
In general, ice will sublimate into water vapour over time. However, if the water vapour in 
the air is already near the saturation limit, such as it was at CZFD, the sublimation rate is 
very slow. Therefore, in this occurrence, a negligible amount of the residual ice would have 
sublimated during the time on the ground.
Some residual in-flight ice can shed from portions of the airframe by melting, ground 
vibration, airframe flexing, and other such processes. When this occurs, it can result in
irregular ridges at ice edges, which would have a significant aerodynamic effect.
In this occurrence, any ice-contaminated surfaces of the aircraft that warmed above 
freezing during the time on the ground would have caused the associated ice to begin to 
melt. This meltwater may have run off onto other sub-zero aircraft surfaces and/or air 
where it could have re-frozen. One possible cause of the melting may have been exposure to 
engine exhaust. The right engine was running in “hotel mode” while on the ground. With the 
influence of light winds and nearby structures, the exhaust plume may have affected only
1 side of the aircraft, causing ice asymmetry on the airframe. In addition, exhaust 
constituents may have altered the saturation level of the water vapour in the air.
The residual in-flight ice accretions could have interacted with the active ground icing 
conditions to produce varied ice shapes and distribution over the airframe. Existing ice 
would have acted as a strong nucleation site for new frost or clear ice formation. Any 
meltwater may have run through frosted areas before re-freezing, creating ice ridges. 
Meltwater could also have frozen during taxi or takeoff.
The shape and distribution of the residual in-flight ice accretions may have changed while 
on the ground, from melting, re-freezing, shedding, and/or growth of frost or ice. 
Asymmetry of ice on the airframe was possible, particularly from the exhaust plume of the 
right engine running in “hotel mode.”
Throughout this analysis, no conclusions were drawn about the visible thickness or extent 
of ice/frost contamination on the aircraft, either residual ice from the flight or icing while 
on the ground. Any amount of contamination adhering to the critical aircraft surfaces can 
severely disrupt its aerodynamics.
Either the residual in-flight ice accretions or the ground icing accretions are alone sufficient 
to account for the loss of control after takeoff. However, in this case, it is likely that both 
occurred. Several accidents have demonstrated that even a thin layer of frost contamination 
is sufficient to cause loss of control immediately after takeoff. 

142 | TRANSPORTATION SAFETY BOARD OF CANADA
Finding as to causes and contributing factors
Weather conditions on the ground were conducive to ice or frost formation, and this,
combined with the nucleation sites provided by the residual mixed ice on the aircraft,
resulted in the formation of additional ice or frost on the aircraft’s critical surfaces.
Because of the additional ice accreted while the aircraft was on the ground, the shape and 
distribution of the ice contamination on the aircraft at takeoff was likely significantly 
different from the residual ice at landing and, as a result, produced very different 
aerodynamic effects.
2.2 Inspection and de-icing
2.2.1 Equipment
The equipment available for inspecting and de-icing West Wind aircraft at CZFD consisted 
of 2 ladders, the tallest of which had a maximum standing height of 2.77 m; a hand-held 
spray system with a small-capacity heated fluid reservoir; and a 20 L container of type I de￾icing fluid. There was an additional small, heated hand-held spray system belonging to 
another operator that was available for use, containing another 20 L. 
The ATR 42’s main wing is 3.76 m above ground, and its horizontal stabilizer is 7.75 m
above ground. These critical surfaces have a combined surface area of more than 66 m². The 
recommended fluid quantity to de-ice an aircraft is 1 L/ m². In the case of an ATR 42, this 
would require more than 66 L. 
Due to the height of the aircraft’s critical surfaces and the maximum standing height of the 
available ladders, neither of the 2 ladders was high enough to permit an adequate 
inspection or to de-ice the ATR 42 wing or horizontal stabilizer. The available de-icing
systems, even if combined, had insufficient fluid capacity to de-ice an ATR 42.
The flight crew did not attempt to de-ice the aircraft, or request to have ground staff de-ice 
it. However, had they done so, the equipment available would not have been adequate, and 
the attempt to de-ice would likely have been unsuccessful. 
2.2.2 Inspection before departure
The WEW282 flight crew were aware of the residual ice on the aircraft before landing at 
CZFD. Following landing and disembarkation, the FO left the cockpit to inspect the aircraft.
As mentioned, neither of the available ladders was high enough to permit an inspection of 
the aircraft, and the FO did not attempt to use either ladder to conduct the inspection. 
Rather, the inspection consisted of the FO walking around the aircraft on the dimly lit apron,
without a flashlight, and looking at the left wing from the top of the stairs at the left rear 
entry door (L2). 
When ATR 42 flight crews inspect the upper surfaces of the aircraft from L2, the whole right 
wing, the top of the horizontal stabilizer and some other parts of the aircraft cannot be seen;
depending on the lighting conditions, even the parts of the aircraft that can be seen may not  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 143
be clearly visible. Likely as a result of this difficulty, no ice or contaminants were noted 
during the upper surface inspection. 
Finding as to causes and contributing factors
Because the available inspection equipment was inadequate, the FO’s ice inspection 
consisted only of walking around the aircraft on the dimly lit apron, without a flashlight, and 
looking at the left wing from the top of the stairs at the left rear entry door (L2). As a result, 
the full extent of the residual ice and ongoing accretion was unknown to the flight crew.
During the walkaround, however, the FO did note contamination on the nose of the aircraft, 
and some residual ice on leading edges of the wings, engine intakes, and the vertical 
stabilizer. The FO also noted that ice was sticking to nearby power lines and vegetation.
While it could not be determined whether the crew were aware that the atmospheric 
conditions during the ground stop were conducive to icing (in the absence of precipitation 
or fog), it was determined that they were aware of some of the resulting ice accumulation.
Because the pilots did not observe any precipitation while on the ground, this may have 
biased their assessment as to the extent of the new contamination on the aircraft.
When the FO returned to the cockpit, he briefly discussed the ice he noticed with the 
captain, and mentioned that there was more ice than he originally thought and that what 
was visible on the ground was also sticking to the aircraft. The captain responded in a way 
that suggested he was not concerned and did not inspect the aircraft himself.
2.2.3 Clean aircraft concept 
The clean aircraft concept is a framework of regulations, standards, policies, and 
procedures that prohibits pilots from attempting to conduct a takeoff with frost, snow, or 
ice adhering to any of the aircraft’s critical surfaces. While this concept or defence is sound 
in principle, it allows for a single-point of failure at the level of flight crew decision making. 
The basis for the flight crew’s decisions in this occurrence will be discussed further in 
section 2.2.4 Flight crew decision making.
Although the clean aircraft concept relies ultimately on the single-point defence of flight 
crew compliance, numerous organizational defences are also in place to help flight crews to 
make decisions, to recognize and mitigate risks, and to reduce the likelihood of aircraft 
departing with contamination.
2.2.3.1 Regulations
Canadian Aviation Regulations (CARs) 602.11(2) states that “No person shall conduct or 
attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its 
critical surfaces.” 
This regulation was in force at the time of the occurrence, but it did not prevent the crew 
from conducting the takeoff with a contaminated aircraft. The regulation itself is clear and 
explicit; however, its effectiveness depends on pilot compliance and the adequacy of other 
defences by the air operator. 

144 | TRANSPORTATION SAFETY BOARD OF CANADA
2.2.3.2 Company guidance
Information, instructions, and guidance regarding icing operations for the ATR 42 can be 
found in a number of company and aircraft manuals. These include the company operations 
manual, which includes the Subpart 705 operations manual, and the ATR 42 standard 
operating procedures (SOPs), which are derived from the ATR 42 Airplane Flight Manual
(AFM), Flight Crew Operating Manual (FCOM), and Quick Reference Handbook. 
In addition to these, as required by CAR 602.11(4)(b), West Wind has a ground icing 
operations program (GIOP) in place to address the standards found in the Commercial Air 
Services Standard 622.11 – Ground Icing Operations. This program is outlined in the 
company’s GIOP manual.
These manuals all contain similar guidance regarding aircraft inspection when icing 
conditions are present, procedures for de-icing or anti-icing, and prohibiting takeoff with 
any frost, ice, or snow adhering to any of the aircraft’s critical surfaces.
The GIOP manual details many of the hazards involved with icing and various sources of ice, 
snow, or frost, but the manual does not specify any explicit procedure for identifying 
ground icing conditions, although regulator guidance276 and the GIOP manual itself state 
that it must. The manual simply states that ground icing conditions exist when frost, ice, or 
snow is adhering or may adhere to the critical surfaces of an aircraft.
The identification of ground icing conditions is the trigger for when ground icing 
procedures, such as inspection and de-icing, are required. While some of the weather 
conditions that present a hazard of ground icing are obvious, such as freezing precipitation, 
others are not as obvious, such as freezing mist that is not in the forecast, as was present in 
this occurrence.
Finding as to risk
If GIOPs do not clearly define a procedure to identify ground icing conditions, flight crews 
may not initiate inspection and de-icing procedures, increasing the risk of aircraft taking off
with contaminated surfaces. 
Although the manuals did not define the ground icing hazard that was present at the time of 
the accident, the crew were aware of icing conditions and inspected the aircraft to a limited 
extent given the available equipment. 
The manuals are clear concerning what to do if contamination is detected during these 
inspections; however, the manuals do not address what equipment might be required to 
inspect and/or de-ice an ATR 42, or what to do if this equipment is unavailable, as was the 
case at CZFD. Specifically, the manuals require that the upper surface of the horizontal 
stabilizer be inspected; however, this upper surface is 7.75 m above ground, making 
inspection from the ground impossible. 
 276 Transport Canada, TP 14052E, Guidelines for Aircraft Ground Icing Operations, Fifth Edition (August 2020). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 145
Finding as to risk
If guidance material that requires the inspection of aircraft surfaces that are not visible from 
the ground does not detail a procedure to conduct this inspection, there is a risk that the 
inspection will not be completed, and surface contamination will go undetected. 
The company manuals also required that any identified deficiencies regarding equipment or 
procedures be reported through the company’s safety management system (SMS). A review 
of the company’s SMS database noted that, although some SMS reports were related to de￾icing procedures, the hazards associated with some de-icing equipment, and the 
cancellation of flights because ground de-icing equipment was unserviceable at airports
typically served by de-icing equipment, there were no SMS reports concerning the 
inadequacy or unavailability of de-icing equipment at airports such as CZFD, or regarding 
departures performed with ice contamination. The absence of reports suggests that the 
inadequate equipment condition was considered normal, and the practice of operating 
without it had become normalized (see section 2.2.4.2 Adaptations and normalization).
Finding as to risk
If staff who are aware of deficiencies in de-icing procedures, or the availability of 
equipment, do not report these hazards through the company’s SMS, there is a risk that the 
hazards will not be documented, assessed, and mitigated.
2.2.3.3 Training
West Wind provided initial and recurrent training programs regarding the hazard of icing 
and had policies regarding the clean aircraft concept. The training provided details on the 
various sources of aircraft icing, including icing that can occur in the absence of 
precipitation. 
Although the training was thorough, it did not include any specific information on what 
equipment would be required to inspect and de-ice an ATR 42, or the availability of 
required equipment at the company’s routine destinations. 
2.2.4 Flight crew decision making
Although there were many administrative defences in place to ensure that the clean aircraft 
concept was understood and followed, the flight crew of WEW282 decided to depart from 
CZFD with contamination on the aircraft’s critical surfaces. 
This section will analyze the many factors that led to that decision and the biases that led
the crew to think that their chosen course of action was safe. It will also analyze why some 
of the defences in place to assist this decision making were ineffective at preventing a 
negative outcome. 
2.2.4.1 Crew resource management
Crew resource management (CRM) is the most widely accepted aid to flight crew decision 
making and a main defence against a wide range of threats, errors, and undesired states. It  

146 | TRANSPORTATION SAFETY BOARD OF CANADA
has come to be understood as an umbrella term that includes virtually every facet of safety 
at a modern air operator.
Crews at West Wind, including the occurrence crew, received regular and recurrent training 
in the many aspects of CRM.
The foundation of CRM is clear, open, and effective communication among crew members. 
This communication fosters effective teamwork, enhances shared situational awareness, 
improves crew decision making, and aids in the prevention, detection, or mitigation of 
errors. Modern CRM also includes the concept of threat and error management (TEM). 
This section will discuss some of the reasons these combined defences were unable to 
mitigate the hazard or prevent the flight crew from departing with contamination on the 
aircraft.
2.2.4.1.1 Intra-crew communication
When the FO reported to the captain that the aircraft had ice on it, the captain was working 
on weight and balance calculations. The discussion between the pilots about the ice lasted 
only 9 seconds before the captain immediately returned to the calculations. 
In response to the FO report that the aircraft was contaminated, the captain acknowledged 
the message, but the discussion ended there. There was no explicit discussion about the 
threat posed by the ice, accepting the risk related to the ice, or about de-icing the aircraft or 
other mitigation.
The FO did not pursue the discussion, suggesting that he did not view the ice as an issue that 
warranted escalation. Six seconds after the discussion ended, the captain told the FO they 
had 7 more passengers than anticipated and called for the before-start check. Three 
minutes later, the FO mentioned the ice again, although this mention was again brief and did
not seem to involve significant concern; the captain’s response similarly did not show 
concern.
The FO’s communication that there was ice on the aircraft was received and understood by 
the captain. However, the statements were only that ice was present and did not include any 
information on the extent of the contamination or suggestions concerning potential 
consequences or mitigations. 
The FO made the statements while the captain’s attention was on other pre-takeoff tasks, 
and the captain immediately went back to those tasks. The fact that neither pilot continued 
the discussion suggests that they both accepted the presence of the ice and thought that 
there was no need to de-ice or delay the flight. 
2.2.4.1.2 Trans-cockpit authority gradient 
The decisional hierarchy or trans-cockpit authority gradient between the 2 pilots was 
relatively flat. Both pilots were experienced in northern operations and had previously been 
paired together.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 147
There was no discussion between the captain and FO on the threat posed by icing on the 
aircraft. Each pilot carried out a quick assessment in isolation. This negated the opportunity 
for the crew to discuss the potential extent of the contamination, and options to address the 
threat posed by icing. The flat authority gradient may have inadvertently created a barrier 
to effective communication. Both pilots may have made assumptions concerning the other 
pilot’s situational awareness and decision making. 
Finding as to risk
When a trans-cockpit authority gradient is relatively flat, communications may be less 
effective and pilots may make erroneous assumptions concerning the other pilot’s 
situational awareness and decision-making, increasing the risk that hazards to flight will 
not be identified and addressed by the crew.
2.2.4.1.3 Threat and error management 
The key principles of TEM are anticipation of, recognition of, and recovery from threats and 
errors. It advocates carefully analyzing potential hazards and taking appropriate steps to 
avoid, trap, or mitigate threats and errors before they lead to an undesired aircraft state. 
Flight crews may trap an error by identifying and correcting it, exacerbate an error by 
making a subsequent error, or have no effect on the error as a result of not detecting it or 
ignoring it.277
TEM briefings can be a very helpful tool to help crews develop a shared understanding of 
the threats and errors perceived by either crew member and to develop a common plan to 
mitigate the risk. TEM briefing checklists are normally developed to help steer crew 
identification and discussion into specific areas that have previously been identified as 
potentially hazardous. 
West Wind had voluntarily introduced TEM briefings in its SOPs before the accident, 
although it was not required to do so by regulation, because the company recognized the 
safety benefits of crews proactively discussing strategies for potential threats. The TEM 
checklist on WEW282 contained a bullet regarding “cold wx ops” (cold weather operations), 
but nothing specific to aircraft icing. However, the checklist is not intended to be exhaustive.
Before the aircraft departed from CZFD on the occurrence flight, the captain’s take-off 
briefing addressed the threat posed by the “black hole” effect. This threat was regularly 
present during night departures at remote airports, and the crew were aware of how to 
manage it. 
Although the crew were aware of icing on the aircraft, this topic was not raised as a threat 
during this briefing, likely because there was only 1 option for mitigation—to not depart—
and the decision to depart had already been made. 
 277 International Civil Aviation Organization (ICAO), document no. 9803, Line Operation Safety Audit (LOSA), First 
1st Edition (2002), pp. 2–4. 

148 | TRANSPORTATION SAFETY BOARD OF CANADA
In terms of analyzing decision making, a decision to take deliberate action that would 
deviate from a known rule or standard procedure is known as an adaptation. Because of the 
deliberate nature of these decisions, TEM briefings can possibly be ineffective in addressing
adaptations that have been made in a single-crew operation or collective decisions in a 
multi-crew situation, because the decision to adapt has already been made.
More specifically, if flight crews have already collectively decided to deviate from a standard 
rule, especially one as explicit as the clean aircraft concept, and it has become common
practice to do so, it is unlikely that this intentional deviation (or adaptation) would be 
raised for discussion during the briefing because the mitigation method intended to trap 
this error would have already been discarded. For example, if a flight crew decided to 
depart overweight, it would be unlikely that they would openly discuss options to mitigate 
this error, when the only clearly safe option—to not depart—had already been decided 
against. 
Finding as to risk
Although TEM briefings are helpful, if they are relied upon to mitigate threats or errors that 
are systemic adaptations, there is a risk that the hazards will continue, especially if the 
threat itself is non-compliance with the mitigation method. 
Put more simply, if choosing to break a rule is the identified error, then there is little point 
in discussing how to avoid doing that. 
While this TEM method might not catch a systemic adaptation shortly before the action is 
taken, it theoretically could be effective if it is applied from a broader perspective. If the 
operator had recognized ahead of time that decisions to depart might be influenced by 
cognitive biases, it may have taken steps to manage this threat. However, there was no 
indication that this overarching threat was identified at the time of the occurrence.
2.2.4.2 Adaptations and normalization
Regulators, manufacturers, and operators develop rules, policies, and procedures that are 
aimed at setting safe limits for operations. However, often influenced by pressure to be 
more productive or cognitive biases, people occasionally make decisions to not stay within 
those limits. When it is repeated over time, this variance results in adaptations of the 
procedures themselves and in deviation from prescribed limits, leading to unsafe 
practices.278
Normally, these procedural adaptations do not have visible and immediate adverse 
consequences. The threats to safety that they pose are not obvious, because the adaptation 
of procedures or regulations does not immediately lead to an accident. Moreover, when 
flights are carried out successfully over an increasingly long period of time, the practice
becomes normalized because the pilots recognize the frequent advantages of the 
adaptations but rarely see the potentially catastrophic consequences. 
 278 J. Rasmussen, “Risk Management in a Dynamic Society: A Modeling Problem,” in Safety Science, Vol. 27, 
Issue 2/3 (1997), pp. 183–213. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 149
With regard to operations in remote locations such as CZFD, the equipment available to 
inspect and de-ice the aircraft was often inadequate, and this was known to flight crews. 
This meant that, once on the ground, if ice was detected, the choice was either to depart 
with some contamination or to cancel the flight and cause a prolonged delay. Because the 
only available de-icing equipment was incapable of de-icing an ATR 42 aircraft, the delay 
created by a decision to de-ice would not be in terms of minutes, it could be in terms of 
days. 
One of these options was clearly extremely negative with regard to productivity, while the 
other had no immediate adverse consequence. When faced with this pressure, in order to 
remain productive, flight crews flying out of these remote locations begin to make 
adaptations.
Finding as to risk
If adequate de-icing equipment is unavailable, especially at locations with routine 
operations, there is a risk that, if ice is detected, the perceived pressure from causing 
extensive delays may lead flight crews to make adaptations to the clean aircraft concept and 
depart with contamination on the aircraft’s critical surfaces. 
Without regular supervision, education, or enforcement of prescribed limits, some people 
will tend to keep adapting the procedures and taking shortcuts until they reach safety 
limits, leading to an unsafe situation and potentially an accident.
From 2014 until the occurrence flight, West Wind conducted 188 ATR 42 stopovers at
CZFD, 101 of which were during the months of October, November, and December. The 
188 flights had an average stopover time of 25 minutes. This quick turnaround time 
indicates that these aircraft were likely never de-iced, and that no takeoffs from CZFD were 
ever delayed or cancelled because of icing conditions. In fact, investigation data indicate 
that some takeoffs likely proceeded with ice on the aircraft. 
Although the 188 flights to CZFD represent a low percentage of West Wind’s total ATR 42 
operations, they are considered representative of West Wind’s operations into remote 
locations.
As previously mentioned, during this time period, no SMS reports filed by flight crews 
identified the inadequate equipment at CZFD, or its effect on decisions to depart with 
contamination on the aircraft, further suggesting that the practice had become a normal 
part of operations.
Finding as to causes and contributing factors
Departing from remote airports, such as CZFD, with some amount of surface contamination 
on the aircraft’s critical surfaces, had become common practice, in part due to the 
inadequacy of de-icing equipment or services at these locations. The past success of these  

150 | TRANSPORTATION SAFETY BOARD OF CANADA
adaptations resulted in the unsafe practice becoming normalized and this normalization 
influenced the flight crew’s decision to depart.
2.2.4.3 Continuation bias
Plan continuation can be described as the tendency for an individual to continue with an 
original plan of action in the face of cues that together, in hindsight, warranted changing the 
plan. In cases of plan continuation, people’s understanding of the situation gradually 
diverges from the situation as it actually turned out to be. Plan continuation almost always 
results from
• early and sustained cues that suggest the plan is safe and that are compelling and 
unambiguous; and
• later cues that suggest the situation is changing but are much weaker, difficult to 
process, ambiguous, or contradictory.279
Once a plan is made and committed to, it becomes increasingly difficult for stimuli or 
conditions in the environment to be recognized as necessitating a change to the plan. Often, 
as workload increases, the stimuli or conditions will appear obvious to people external to 
the situation; however, it can be very difficult for a pilot caught up in the plan to recognize 
the saliency of the cues and the need to alter the plan.280
In this occurrence, even before landing at CZFD, the crew had developed a plan that 
involved a prompt departure and did not involve de-icing the aircraft. There were several 
early and sustained cues on the inbound flight that suggested to the crew that this plan was 
safe, including:
• the fact that 2 aircraft had proceeded safely to CZFD before the occurrence flight;
• the compelling knowledge that they had done this safely before;
• the normal aircraft handling despite the degraded performance alerts; and
• the absence of significant concern or discussion raised by either pilot about the 
current conditions.
Later cues that came to the crew suggesting a change in plan may be required, were slightly 
weaker, uncertain, and even contradictory. When the FO returned to the cockpit following 
the walkaround, the new information he provided regarding the ice was neither detailed 
nor compelling. At around the same time, another aircraft departed safely, which served to 
contradict any potential perception that the icing was significant. Finally, when the crew 
completed their last check for ice before departure, although the captain reported that the 
spoiler, the representative surface he was required to inspect for ice, was clear, the FO’s 
view was limited, and the FO told the captain that he could barely see the spoiler on his side. 
 279 S. Dekker, The Field Guide to Understanding Human Error (Ashgate, 2006), p. 94.
280 E. Muthard and C. Wickens, “Factors that Mediate Flight Plan Monitoring and Errors in Plan Revision: 
Planning Under Automated and High Workload Conditions,” presented at the 12th International Symposium 
on Aviation Psychology, Dayton, Ohio (14–17 April 2003). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 151
As a result, the flight crew’s assessment of the severity of the ice on this final check was 
based on incomplete information.
Finding as to causes and contributing factors
Although the flight crew were aware of icing on the aircraft’s critical surfaces, they decided 
that the occurrence departure could be accomplished safely. Their decision to continue with 
the original plan to depart was influenced by continuation bias, as they perceived the initial 
and sustained cues that supported their plan as more compelling than the later cues that 
suggested another course of action.
2.2.5 Recommendations following pilot survey
During July and August 2018, the TSB sought information from pilots operating into and out 
of remote airports in Canada. To gather this information, an online survey was conducted. 
The survey had 655 responses and provided useful insight into compliance with the clean 
aircraft concept and the adequacy of de-icing and anti-icing facilities at remote locations. 
The key takeaways from the results can be summarized with the following statements. In 
terms of a percentage of respondents:
• 74% indicated that they had witnessed pilots take off with contaminated critical 
surfaces in the past 5 years.
• 39% indicated that they are never or rarely able to have their aircraft de-iced.
• 35% indicated that they never or rarely have access to ground equipment that
enables adequate de-icing of their aircraft at remote airports.
• 31% indicated that they never or rarely have access to ground equipment that 
enables effective inspection of the aircraft’s critical surfaces.
In December 2018, once the data from the survey were analyzed, and connections were 
established between the data and the underlying factors involved in this occurrence, the 
Board issued 2 recommendations to address the 2 identified areas of greatest risk: the 
availability of adequate de-icing and anti-icing equipment, and compliance with the clean
aircraft concept.
TC’s latest responses (September 2020) and updates (November 2020) to these
recommendations indicated that TC had created a stakeholder working group, improved
training and produced material to raise awareness of the hazards of aircraft taking off with
contaminated critical surfaces. The COVID-19 pandemic has presented challenges to the 
industry and to TC. These challenges have delayed the development of concrete actions to 
ensure proper de-icing and anti-icing equipment is available to reduce the likelihood of 
aircraft taking off with contaminated critical surfaces, and prevented most of TC’s planned 
targeted inspections aimed at increasing compliance with CAR 602.11(2). 
While these actions, once seen through to completion, may have the potential to 
substantially mitigate the risk associated with the safety deficiency, at the time of report 
publication, these actions had yet to be implemented. 

152 | TRANSPORTATION SAFETY BOARD OF CANADA
Finding as to risk
Until actions are implemented to address the availability of anti-icing and de-icing 
equipment (TSB Recommendation A18-02) and compliance (TSB Recommendation A18-
03), there remains a persistent risk that pilots will not comply with the clean aircraft 
concept and will continue to take off with contaminated aircraft.
2.3 Takeoff and loss of control
2.3.1 Performance calculations
When the crew prepared take-off performance calculations for departure, they used the 
METAR for CYSF that they had received on approach to CZFD. This METAR indicated a 
temperature of −10 °C, a few clouds at 1400 feet AGL, and a broken ceiling at 2300 feet AGL.
Guidance in the AFM states that atmospheric icing exists when the temperature is below 
10 °C and visible moisture in any form, such as clouds, is present. It does not specify 
whether the aircraft has to be in these referenced clouds, or whether the existence of the 
clouds alone is sufficient. For example, if clouds were forecast at 200 feet, it might be clear 
that atmospheric icing conditions existed on departure, but if the clouds were few and at 
2000 feet, it may not be as clear whether icing conditions prevailed, or not.
Guidance in the FCOM states that speed limitations must be complied with as soon as the 
icing conditions are met; however, this relies on the AFM explanation of atmospheric icing 
and does not clarify whether speed limitations are required for clouds that will not be 
entered during the takeoff. 
When aircraft are certified, certification standards require the aircraft to be able to 
encounter icing while on the take-off path, which continues from the ground up to 
1500 feet. Aircraft manufacturers must establish icing speeds that will be used to maintain 
obstacle clearance requirements following an engine failure on takeoff in icing conditions. 
Because these speeds are calculated for the take-off path, it would therefore follow that, if 
icing conditions exist below 1500 feet AGL, icing speeds should be used for the takeoff. This 
information, however, is not supplied to pilots in any of the guidance provided by the 
manufacturer, company, or regulator, outside of interpreting the regulations or certification 
standards themselves. 
The use of appropriate take-off speeds is important to ensure that the aircraft can clear 
obstacles on takeoff or stop on the remaining runway, should the crew need to abort 
takeoff. Because icing speeds are always higher than non-icing speeds, their use increases
the take-off distance required, or, in cases where the distance is limited, reduces the 
allowable take-off weight.
Finding as to risk
If the guidance provided to pilots to help them determine when to select take-off icing 
speeds is not clear and well-defined, flight crews may select a take-off speed or operating  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 153
weight that will result in the aircraft being unable to meet the minimum performance 
requirements set by certification standards, thereby increasing the risk of an accident. 
Before the occurrence departure, the flight crew perceived that they would not encounter 
in-flight icing on takeoff, and, as a result, the crew selected non-icing speeds for the takeoff
and Level 1 for ice protection. On takeoff, there was likely no further significant in-flight ice 
accretion because there was no precipitation and because the aircraft never entered the
cloud layers that were likely present at approximately 1400 and 2300 feet AGL, as reported 
at CYSF. Therefore, it could be interpreted that the protection afforded by these icing speeds 
was not required.
Similarly, the flight crew did not apply performance penalties that may have been required 
because of the unpaved runway surface, which was possibly also contaminated with snow 
patches.
Softer runways normally require longer take-off distances and therefore penalties when 
calculating take-off performance. There was no specific guidance supplied by the aircraft 
manufacturer for operations on sealed-gravel runways, and the regulator’s guidance stated 
that frozen unpaved surfaces had qualities similar to those of paved surfaces. With 
knowledge of this guidance, the crew determined that a performance penalty was not 
required for the departure.
Additionally, the most recent runway surface condition report, issued 11 hours before the 
occurrence departure, recorded that 40% of the runway was covered in snow patches. 
However, this condition no longer existed on the next report, 13 hours later, so it could not 
be determined whether the condition existed at the time of departure. Runway surface 
contamination greater than 25% requires an additional penalty, but no penalty was 
calculated by the flight crew.
Finding as to risk
If flight crews do not apply the take-off performance calculation penalties required for
contaminated or unpaved runways, they might operate at take-off weights or on runway 
lengths that do not meet, their aircraft’s capabilities, increasing the risk of a runway 
excursion or accident.
2.3.2 Aircraft contamination
The aircraft accumulated ice on approach, and, although most of it was shed by the de-icing
system, some remained on landing. This residual ice acted as nucleation sites for the 
accretion of further ice during the aircraft’s 48-minute stop on the ground.
During the investigation, the physical evidence of ice contamination on the critical surfaces 
of the aircraft was difficult to distinguish from that accumulated following the accident. 
Therefore, an aerodynamic analysis was conducted to identify the presence and effect of ice 
contamination.  

154 | TRANSPORTATION SAFETY BOARD OF CANADA
Finding as to causes and contributing factors
As a result of the ice that remained on the aircraft following the approach and the additional 
ice that had accreted during the ground stop, the aircraft’s drag was increased by 58% and 
its lift was decreased by 25% during the takeoff.
2.3.3 Loss of control in the roll axis
Finding as to causes and contributing factors
During the takeoff, despite the degraded performance, the aircraft initially climbed; 
however, immediately after lift off, the aircraft began to roll to the left without any pilot 
input. This roll was as a result of asymmetric lift distribution due to uneven ice 
contamination on the aircraft.
To counteract this roll, the captain added full right aileron and the aircraft began to roll 
right, although at a reduced rate compared to what he expected to normally occur, given the 
amount of input.
Finding as to causes and contributing factors
Following the uncommanded roll, the captain reacted as if the aircraft was an 
uncontaminated ATR 42, with the expectation of normal handling qualities and dynamic 
response characteristics; however, due to the contamination, the aircraft had diminished 
roll damping resulting in unexpected handling qualities and dynamic response.
The flight data from the departure were compared with hundreds of other flights, and it was 
determined that, at this moment, there was a degradation in roll control authority; however, 
subsequent analysis determined that the degradation was not critical and that the ailerons 
in fact had sufficient roll control authority to counteract the asymmetric lift. 
Four seconds after the initial left roll and attempted recovery, the airplane continued to roll 
to the right, through level, and entered a more significant right bank, followed 4 seconds 
later by an even more significant left bank.
Finding as to causes and contributing factors
Although the investigation determined that the ailerons had sufficient roll control authority 
to counteract the asymmetric lift, due to the unexpected handling qualities and dynamic 
response, the roll disturbance developed into an oscillation with growing magnitude and 
control in the roll axis was lost.
On the 3rd oscillation, when the roll angle reached its peak, the stall warning sounded and 
the nose was lowered. Although the aircraft was close to the stall at this point, the stick 
pusher had not yet activated, and therefore this nose-down pitch movement was likely a 
result of a control input made by the captain. 
During the 4th oscillation, after reaching a peak of 142 feet above ground, the aircraft began 
to descend. The captain raised the nose, but the bank angle also began to increase, now back 
towards the left and into the 5th oscillation. Due to the increasing bank, the aircraft 
continued to descend, the stall warning sounded again, and the aircraft collided with the 
ground shortly after the peak of the 5th oscillation.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 155
Finding as to causes and contributing factors
This loss of control in the roll axis, which corresponds with the known risks associated with 
taking off with ice contamination, ultimately led to the aircraft colliding with terrain. 
2.4 Collision with terrain
Finding as to causes and contributing factors
The aircraft collided with the ground in relatively level pitch, with a bank angle of 30° left. 
As a result of the sudden vertical deceleration upon contact with the ground, the aircraft 
suffered significant damage, which varied in severity at different locations on the aircraft 
because of the impact angle and the variability in structural design.
2.4.1 Estimation of impact forces
The aircraft struck the ground in an area of down-sloping terrain. Once the fuselage struck 
the ground, the aircraft began to rotate or yaw to the left. By the time the aircraft came to 
rest, it was oriented nearly 90° in relation to the path of travel during the impact sequence. 
As a result of this rotation, although the peak longitudinal (forward) acceleration force was 
estimated to be 4g in the direction of travel, the aircraft and its occupants received 
significant lateral loads nearing 4g as well. The exact initial impact force in a vertical 
direction was not determined, but it was not large enough to cause the passenger seats to 
deform to the left when the aircraft collided with the ground when banked 30° to the left.
2.4.2 Crashworthiness
Crashworthiness is generally defined as the ability of an aircraft and its internal systems 
and components to protect the occupants from injury in the event of a crash. Aircraft design 
regulations require that aircraft “structure must be designed to give each occupant every 
reasonable chance of escaping serious injury in a minor crash landing.”281
During the U.S. Federal Aviation Administration (FAA) vertical drop test of an ATR 42, the 
aircraft fuselage sustained major structural damage and would not have given each 
occupant every reasonable chance of escaping serious injury. The main landing gear 
housing structure, which served as the lower portion of the centre fuselage section, did not 
progressively crush in the same way as the remaining fuselage. This resulted in the centre 
fuselage section, above the main landing gear housing structure, sustaining major structural 
damage as the inertial load from the wing crushed the upper portion of the fuselage, 
resulting in a loss of survivable space for the occupants in the centre section of the 
passenger cabin.
In this occurrence, the vertical impact velocity of the aircraft was significantly lower than 
that in the FAA drop test (as evidenced by the amount of deformation of the seats), yet the 
 281 Federal Aviation Administration (FAA), Code of Federal Regulations (CFR), Title 14: Aeronautics and Space, 
Part 25: Airworthiness Standards: Transport Category Airplanes, Subpart C: Structure, section 25.561(b)
(Amendment 25-23, effective 08 May 1970). 

156 | TRANSPORTATION SAFETY BOARD OF CANADA
key structural damage was almost identical to that observed in the FAA’s test. Specifically, 
the main landing gear housing structure, beneath the passenger cabin, did not exhibit signs 
of vertical crushing, and the area above it was significantly damaged.
The ATR 42-320 certification basis was set in 1985 to the FAA’s Code of Federal Regulations, 
Title 14: Aeronautics and Space, Part 25: Airworthiness Standards: Transport Category 
Airplanes (FAR 25), up to and including amendment 54. Although FAR 25.561 was amended 
in 1988 to include a requirement that seats and supporting structures must not deform in a 
manner that could impede rapid evacuation of occupants, this requirement did not apply to 
the ATR 42-320.
To protect occupants, an aircraft’s structure must absorb impact energy in a way that 
eliminates or minimizes cabin deformation and reduces the acceleration loads transmitted 
to the occupants. Although the certification regulations require that seats and their 
attachments meet requirements for inertial loads transmitted from the occupants, the 
certification standard does not specify specific crash landing loads for fuselage structure 
design or specify that the fuselage structure must be designed for impact energy absorption.
Finding as to causes and contributing factors
The design standards for transport category aircraft in effect at the time the ATR 42 was 
certified did not specify minimum loads that a fuselage structure must be able to tolerate 
and remain survivable, or minimum loads for fuselage impact energy absorption. As a 
result, the ATR 42 was not designed with these crashworthy principles in mind.
Instead of being designed for crashworthiness, the lower portion of the centre fuselage 
section, specifically the main landing gear housing structure, was designed to be rigid in 
order to transfer loads from the landing gear.
2.4.3 Damage from the impact
In keeping with the modest vertical energy during the impact, apart from the centre 
fuselage section, the damage to the majority of the fuselage was modest. The upper portions 
of the forward and aft fuselage sections had maintained their approximately circular shape, 
indicating that the lower portion of these sections had effectively absorbed the impact 
energy. 
In contrast to this modest damage, however, the centre fuselage section sustained severe 
structural damage, and its upper portion collapsed.
The structural damage compromised the survivable space, the restraint systems, the 
evacuation aisle, and power to the emergency lights and communications systems; it limited 
access to the emergency exits, and delayed and impeded the evacuation. The effects of the 
damage resulted in the injury and trapping of occupants and the death of 1 passenger.
2.4.3.1 Wing collapse
In this aircraft type, the main landing gear is stowed inside the lower portion of the centre 
fuselage section, and the landing gear housing structure is built using solid bulkheads joined  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 157
by a solid keel beam. Following the accident, no sign of appreciable vertical crushing was 
found in this area, indicating that the structure was too rigid to absorb the impact energy 
effectively in the vertical direction. This absence of crushing, or energy attenuation, resulted 
in the full impact force being distributed through the centre fuselage section above the 
landing gear housing structure.
Mounted directly above the centre fuselage is the aircraft’s wing. The wing carries a 
significant load, given that the engines are mounted on it and the built-in fuel tanks carrying
all of the aircraft’s fuel are contained within it. 
Finding as to causes and contributing factors
On impact, the induced acceleration was not attenuated because the landing gear housing 
did not deform. This unattenuated acceleration resulted in a large inertial load from the 
wing, causing the wing support structure to fail and the wing to collapse into the cabin.
The crushing of the upper portion of the centre fuselage section by the inertial force from 
the wing severely compromised the structural integrity of the fuselage as a whole. This 
crushing reduced the survivable space for occupants in the centre section of the passenger 
cabin and was a key factor leading to the transverse fracture of the fuselage at the location 
just forward of the forward wing spar. 
Finding as to risk
When the wing collapsed, the integral fuel became uncontained and leaked out, significantly 
increasing the risk of a post-impact fire at a time when passengers were unable to evacuate. 
Finding as to risk
Following the wing collapse, the leaked fuel entered the survivable space, and with the 
outside temperature of approximately –10 °C, the passengers who were soaked in fuel faced 
an increased risk of hypothermia. 
Finding as to risk
The collapse also resulted in structural and terrain hazards entering the cabin survivable 
space. These intrusions increased the risk of injuries for those occupants flailing in their 
seats during the accident sequence, and also to evacuating passengers who had to climb 
through the cabin, over seats and hazards, to evacuate the aircraft.
2.4.3.2 Floor structure
Differential vertical crushing of the lower portions of the fuselage sections also resulted in 
fracture and collapse of the floor structure at locations forward and aft of the main landing 
gear housing structure.
The cabin floor frame of the occurrence aircraft was constructed using transverse beams 
and seat tracks. There were 2 types of connections between the transverse beam and the 
seat tracks, depending on whether a single piece of seat track passed over the transverse  

158 | TRANSPORTATION SAFETY BOARD OF CANADA
beam (type I), or if 2 seat tracks made an end-to-end connection at the transverse beam 
(type II). 
The type II joint design is considered weaker than the type I joint design. In keeping with 
this view, all type II joints of the floor frames of the occurrence aircraft failed, whereas the 
type I joints did not. The failures were found to be caused by transfer of the longitudinal 
load from the seat tracks to the joint.
The cabin floor buckled from the rear of the passenger cabin toward the centre of the 
passenger cabin. This was due to the twisting between the centre and aft fuselage sections
and the differential crushing damage to the lower portion of the centre and aft fuselage 
sections. It is likely that the rigid design of the lower portion of the centre fuselage section
contributed to such abnormal floor structure deformation and damage.
2.4.3.3 Flight attendant seat
The laboratory examination of the flight attendant (FA) seat determined that it had 
undergone unapproved repairs on the honeycomb structure sandwich panel. As a result, 
there were a significant number of bubbles and unfilled voids at the bonding interface of the 
sandwich panel, and the strength of the seat-structure assembly was likely far lower than it 
was in the original design. This was likely the reason the FA’s seat failed and broke into 
pieces in this occurrence.
The shop that performed the last repair on the structural assembly of the FA seat is no 
longer in business. Because of this, no further information could be obtained as to why it 
selected a standard composite repair procedure not applicable to the FA seat. 
A review of the inspection and repair procedure for the FA seat in the Component 
Maintenance Manual (CMM) determined that the inspection and repair procedures for the 
structure assembly of the FA seat were not clear. While the CMM stated that metal 
components were not repairable, it was not clear whether a “shaped honeycomb structure 
sandwich panel” was considered a metal component. Strictly speaking, the honeycomb 
sandwich panel is not a metal component because of the presence of adhesive bonding 
layers in its structure. It is normally referred as either “honeycomb sandwich panel” or 
“composite” in aircraft structural repair. 
The ambiguity in inspection and repair procedures for the structure assembly of the FA seat 
was likely one of the factors contributing to the unapproved repair of the FA seat, as it may 
have caused confusion for a technician who did the inspection and repair. A post￾occurrence examination of an FA seat from another West Wind ATR 42, found signs of 
similar unapproved repairs, suggesting that the misunderstanding of the CMM with regards 
to the repairability of the honeycomb panels may be a widespread issue.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 159
2.5 Injuries 
All passengers and crew were injured. Many were rendered temporarily unconscious. The 
captain and 9 passengers were seriously282 injured, and 1 of these passengers later died as a 
result of the injuries received.
The sequence of events during the impact and subsequent slide induced injuries from initial 
vertical forces, injuries from jackknifing and flailing, crushing injuries as a result of the wing 
and floor structure collapse, more severe flailing injuries due to the reduced survivable 
space, and injuries from lateral acceleration forces and associated lateral flailing. Due to the 
amount of passenger displacement and collision with aircraft parts, it was impossible to 
determine the exact nature or order of injuries for each passenger. 
However, an analysis of injuries indicated that head, body, and leg trauma were more 
common in the middle-forward left section of the aircraft. This is consistent with the degree 
of crushing in this area, given that the living space in this area was compromised by the 
wing above collapsing downwards, and the floor below being pushed upward. 
The analysis also indicated that back-related trauma was more common in the middle-rear 
right section of the aircraft. This is consistent with the lateral forces and rotation applied to 
this side of the aircraft, which resulted in lateral deceleration forces for occupants of seats 
that had a compromised restraint system.
2.5.1 Serious and fatal passenger injuries
Finding as to causes and contributing factors
The reduced survivable space between the floor above the main landing gear and the 
collapsed upper fuselage caused crushing injuries, such as major head, body, and leg 
trauma, to passengers in the middle-forward left section of the aircraft. Of the 3 passengers 
in this area, 2 experienced serious, life-changing injuries and 1 passenger died.
2.5.2 Other injuries to passengers and flight crew
Although the occurrence impact forces were within human tolerance levels, an analysis of 
occupant injuries indicated that many of the passengers and the captain received serious 
velocity-related injuries, such as compression injuries and back fractures.
The initial impact forces (vertical downward deceleration force of approximately 4g) did 
not exceed the passenger seat design limits of 4.0g lateral, 7.2g vertical (downward), or 9.0g
longitudinal (forward). Although most seats were pushed into other seats, some were 
deformed, and many had displaced seat tracks, the flight crew and passenger seats all 
performed as designed. 
The deformations, displacements, and associated loss of restraint effectiveness were 
primarily due to the collapse of part of the floor structure, not the failure of the seats. Given 
 282 According to the TSB classification of occurrence injuries. 

160 | TRANSPORTATION SAFETY BOARD OF CANADA
that the seat structures were all attached to the floor, any floor deformation could 
significantly reduce the overall effectiveness of restraints, regardless of seat or belt type. 
With seats already vulnerable as a result of the floor deformation, when the aircraft turned 
to the left, the force applied laterally to the fuselage approached the seats’ side load limit 
of 4g. This resulted in a deflection of the seats to the right, which likely contributed to the 
injuries sustained by those in the right-side seats.
Finding as to causes and contributing factors
The collapse of part of the floor structure compromised the restraint systems, limiting the 
protection afforded to the occupants when they were experiencing vertical, longitudinal,
and lateral forces. This resulted in serious velocity-related injuries and impeded their 
ability to take post-impact survival actions in a timely manner.
2.5.2.1 Adult restraint systems
The passenger seats were the type with locked-out seatbacks, designed to remain upright 
after flexing following an impact from the rear, and were equipped with typical 2-point lap 
belts.
When occupants are exposed to impact forces, this can result in several different types of 
velocity-related injuries, such as flail injuries from uncontrolled arm, leg, and head 
movements; jackknife injuries from the upper torso folding forward or to the side; and/or 
submarining injuries, from sliding out from under a lap belt. 
When compared with passengers in seats with shoulder harnesses, passengers in seats with 
2-point lap belts that do not restrain the torso are at a greater risk of concentrated 
acceleration forces around the hips and abdomen and at a greater risk of serious injuries 
from flailing, jackknifing, and submarining. 
To mitigate the risk of injury to occupants seated in aircraft seats without torso restraints 
or head impact protection, such as the occurrence aircraft, it is important that those 
occupants assume a proper brace position. The seats in the ATR 42 were designed before 
head-impact protection criteria were required; therefore, the only remaining mitigation for 
the risk of flailing, jackknifing, or submarining injuries was reliance upon passengers to 
assume a correct brace position before or during an impact sequence. 
There are many factors that affect the probability of a passenger bracing before impact, 
including the anticipation of a collision, timely instructions from the crew, or an 
understanding of the need to brace, by reading the safety-features card. Because these 
factors are often absent, passenger bracing may not be done correctly.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 161
Finding as to causes and contributing factors
Most passengers in this occurrence did not brace before impact. Because their torsos were 
unrestrained, they received injuries consistent with jackknifing and flailing, such as hitting 
the seat in front of them.
2.5.3 Infant injury 
The occurrence aircraft had no child restraint systems, nor was the operator required to 
provide these. Similar to what has been documented in other accidents, in this occurrence, a
parent was unable to effectively restrain their infant on their lap during the impact 
sequence. As a result, the infant was projected into the seat in front, receiving projection￾related injuries and subsequent crushing injuries from being trapped.
In 2015, the TSB recommended that TC work with industry to develop child-restraint 
systems for infants and young children and to mandate their use. The regulator responded 
that it would examine the issue, but at the time of writing this report, there has been no 
progress toward any action. 
Finding as to causes and contributing factors
Given that regulations requiring the use of child-restraint systems have yet to be 
implemented, the aircraft was not equipped with these devices. As a result, the infant 
passenger was unrestrained and received flail and crushing injuries.
2.5.4 Flight attendant injury
The FA seat failed on impact; as a result, the FA was projected into the aisle, suffered
multiple minor injuries, was incapacitated for the remaining 9 seconds of the impact 
sequence, and was delayed in responding to the crash. 
The FA seat was found to have a significant number of defects in its seat structure as a 
result of repairs that were not in accordance with the CMM for the seat. The defects in the 
seat structure were likely the main reason it broke into pieces during the occurrence. 
Finding as to causes and contributing factors
As a result of unapproved repairs, the FA seat failed on impact, resulting in injuries that 
impeded her ability to perform evacuation and survival actions in a timely manner.
2.6 Evacuation
After the FA was able to free herself from the projected FA seat, she attempted to 
communicate with the flight crew but was unable to because the transverse fracture of the 
fuselage had disabled the power supply for intra-crew communications. The FA therefore 
initiated evacuation of the passengers. 
The FA attempted to open the rear entry door (L2) to evacuate the aircraft; however, she
was unable to do so. The structural damage from impact had resulted in the displacement of 
internal cabin partitions and caused the handle for the L2 door to become trapped behind  

162 | TRANSPORTATION SAFETY BOARD OF CANADA
the partition, restricting the FA’s and passengers’ access to it. The FA and able-bodied 
passengers instead had to kick the service door (R2), which was partially blocked by 
terrain, for several minutes before it finally opened and occupants were able to exit the 
aircraft. 
Similarly, the damage displaced cargo poles that were part of the cargo restraint systems; as 
a result, cargo spilled loose within the forward cargo hold, blocking the escape route from 
the cockpit. Because of this blockage, the evacuation of the flight crew was significantly 
delayed. The FO evacuated through the cockpit hatch, and the captain had to be extracted 
through the hatch with outside assistance.
As a result of these difficulties, it took approximately 20 minutes for the first 17 passengers 
remaining in the aircraft to evacuate, while other passengers remained trapped. The last 
passenger was removed from the wreckage 3 hours after the accident.
The current design standards for transport category aircraft state that equipment, 
passenger compartment cargo, and any other large masses in the cabin, must be positioned 
so that, if they break loose, they will be unlikely to prevent the use of any of the escape 
facilities intended to be used following an emergency landing. However, this standard 
became applicable after the ATR 42 was type-certified and, as a result, did not apply to the 
occurrence aircraft. 
Finding as to risk
As shown in this occurrence, on aircraft certified to older standards, there is a risk that 
displacement of cargo restraint systems and cabin partitions that are positioned adjacent to 
an evacuation route could impede the evacuation route for survivors. 
2.7 Regulatory oversight
2.7.1 Surveillance planning
All transportation companies have a responsibility to manage the safety risks within their 
operations. A move toward safety management systems (SMS) has great potential to 
enhance safety by encouraging operators to put in place a systemic approach to manage 
safety proactively. 
Given that companies will inevitably have varying degrees of ability or commitment to 
manage safety effectively, the regulator needs to ensure compliance with existing 
regulations. To do this, the regulator needs to be able to provide oversight in a manner that 
encourages the proactive identification and mitigation of risks, while intervening when 
necessary to ensure, at a minimum, regulatory compliance. 
Guidance from the International Civil Aviation Organization (ICAO)283 states that all 
significant aspects of an operator’s procedures and practices should be evaluated at least 
 283 International Civil Aviation Organization (ICAO), document no. 8335, Manual of Procedures for Operations 
Inspection, Certification, and Continued Surveillance, 5th Edition (2010). 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 163
once every 12 months. Before 2012, TC’s surveillance policies and procedures met this 
criterion, as companies in all sectors were required to undergo an inspection at least every 
12 months and an audit every 3 years. 
However, in 2012, TC changed its surveillance policy and increased the surveillance interval 
for program validation inspections (PVIs) to a maximum of 3 years and for assessments to
5 years. The selection of a surveillance interval for a particular operator would be
determined based on a company’s risk-profile score, calculated using the National Aviation 
Safety Information Management System (NASIMS). The change to this policy was based on 
the premise that companies assessed as low risk and/or low complexity would be more 
effective at managing safety than others, using tools such as SMS, quality assurance 
programs, and other defences. 
Between 2010 and 2013, the regulator had identified several concerns with non￾conformance within the quality assurance and safety oversight components of West Wind’s 
SMS. Despite these identified issues, in the months following the 2013 PVI, the regulator
adjusted the company’s surveillance schedule from planned annual PVIs to a 4-year interval
in accordance with newly released internal guidance. This action was based on the 
regulator’s computed risk score for West Wind at the time (2D, low risk high impact). As a 
result of this adjustment, direct regulatory oversight of the company was significantly 
reduced.
Between the 2013 PVI and the 2016 assessment, TC’s surveillance of West Wind was limited 
to administrative review of documents, approved check pilot monitors, and cabin safety in￾flight checks. During that 3-year period, the company was not subject to any additional 
surveillance activities, such as assessments, PVIs, or process inspections (PIs).
Based on the issues identified by the regulator from 2010 to 2013, it is unclear how TC 
determined that it had adequate assurances to place West Wind on a 4-year planned 
surveillance interval. As seen in this occurrence, this decision reduced the oversight of a 
company that did not consistently demonstrate the ability of its SMS to effectively manage 
safety. This became readily apparent during the 2016 assessment, which resulted in major 
and moderate findings of non-compliance. 
From 2012 to 2019, one of the primary tools TC used to determine a company’s surveillance 
interval (i.e., 1 to 5 years) was the applicable risk-profile score in NASIMS. The risk-profile 
score obtained through NASIMS was one of the key considerations during TC’s annual 
surveillance planning. 
However, as seen in this occurrence and identified in the 2012 Spring Report of the Auditor 
General of Canada and TSB Aviation Investigation Report A13H0001, NASIMS was not 
regularly updated, either because there were no surveillance activities or because database 
updates were not completed in a timely manner. 
Many of the responses to the West Wind risk-profile questions in NASIMS had not been 
updated since 2012, and some that had been updated were not done so accurately. For 
example, a major finding of non-compliance identified in the 2013 PVI was not recorded as  

164 | TRANSPORTATION SAFETY BOARD OF CANADA
such. As a result of the responses not being updated regularly, and the inaccuracy of some of 
the responses that were updated, West Wind’s risk-profile score did not accurately reflect 
its actual risk profile. 
After West Wind’s initial NASIMS risk-profile score in 2012, the company’s risk-indicator 
value initially decreased and then remained unchanged for almost 2 years, due to the 
absence of updates. West Wind’s score dropped again in 2015, reaching a low just before 
TC’s 2016 assessment. As a result, although there were likely ongoing issues at the company 
with regard to regulatory compliance, as evidenced by the 8 major and 2 moderate findings 
during the 2016 assessment, TC’s process for monitoring changes in company risk profiles 
was inaccurately showing that risk levels decreased from 2013 to the 2016 assessment. 
The results of the 2016 assessment, and the resulting spike in West Wind’s NASIMS risk￾indicator number, demonstrate that, for the period from 2013 to 2016, TC did not have an 
accurate understanding of the risks present at the company.
In order for NASIMS, or any other risk-profile system, to be effective, regular and accurate 
updates to risk-indicator scores are required. 
Finding as to risk
If company risk profiles maintained by the regulator are not up to date and accurate, 
changes in a company’s risk profile may go undetected and surveillance activities might be 
reduced, allowing unsafe conditions to develop or persist. 
2.7.2 Inconsistent application of policies and procedures
2.7.2.1 General
The investigation revealed a number of instances in which TC’s surveillance policies and 
procedures were inconsistently applied to the oversight of West Wind. This is not the first 
time that such inconsistencies in TC’s oversight of commercial aviation in Canada have been 
identified. As detailed in the findings of several TSB investigations, there have been a 
number of past examples where TC has been slow to either identify or to rectify unsafe 
conditions at an operator (Appendix H). 
2.7.2.2 2016 assessment
After a 3-year period of very little oversight activity, TC initiated an assessment of West 
Wind in 2016. The 2016 assessment revealed numerous major findings throughout the 
company’s operations, most of which were related to SMS requirements under CARs
Subpart 107. 
While the assessment was underway, during both on-site and post-surveillance decision
making, TC considered taking certificate action, such as suspension or cancellation of the 
company’s air operator certificate; however, in September 2016, West Wind voluntarily 
suspended its Subpart 705 operations, and shortly thereafter suspended its Subpart 703 
and 704 operations. TC’s decision making on certificate action was influenced by West 
Wind’s decision to suspend operations, as well as the company’s acceptance of TC’s findings  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 165
and West Wind’s willingness to complete short- and long-term corrective action plans 
(CAPs). 
Since the company, which is an SMS enterprise, expressed interest in addressing the 
identified problems through the CAP process, regional TC personnel understood that 
national policy obligated them to follow the CAP process with West Wind. In addition, 
regional TC personnel understood that certificate or enforcement action would be 
counterproductive, since it seemed to contradict TC’s approach to providing oversight to 
SMS enterprises. 
As a result, regional TC personnel selected strategies for dealing with West Wind that were 
not consistent with national-level surveillance policies and procedures at the time. These 
decisions allowed unsafe conditions to persist at West Wind. 
Examples include the following:
• TC terminated the assessment without assessing SMS component 1 – Safety 
Management Plan and made no provision to ensure that it was assessed later. As a 
result, TC did not have assurances that the company’s safety management plan 
would be effective at ensuring the company’s timely return to a state of compliance.
• TC assessed SMS component 3 – Safety Oversight as compliant, despite the fact that 
some elements were assessed as only partially implemented. 
• TC assessed SMS component 4 – Quality Assurance as non-compliant. TC had 
previously identified this component as being non-compliant on multiple occasions 
since 2010, and, although actions were taken individually, nothing was done to 
address the systemic nature of the recurring issue. 
• The assessment report identified legacy issues, lack of communication, and 
complacency; however, it did not provide any supporting evidence or analysis for 
these issues. 
• Despite multiple major findings of non-compliance, TC did not issue any detection 
notices to West Wind. As a result, critical information needed to support certificate 
action was not captured. 
The results of the 2016 assessment met several of the criteria considered mandatory for 
invoking the Oversight Advisory Board (OAB). In particular, it involved a high-profile 
operator with multiple major findings, and an operator that would be placed under 
enhanced monitoring (EM). 
Despite this, the OAB was not consulted about West Wind following the 2016 assessment, 
and, as a result, the regional TC office did not receive national-level guidance on the 
appropriate course of action. Without consulting the OAB, regional TC personnel, who were 
unaware of newly published surveillance procedures, placed West Wind under EM
following the 2016 assessment, despite multiple major findings and new surveillance 
procedures directing them to escalate the situation to national oversight.  

166 | TRANSPORTATION SAFETY BOARD OF CANADA
2.7.2.3 On-site follow-up of West Wind’s corrective action plans
TC policies and procedures (i.e., Staff Instruction [SI] SUR-001) state that CAP 
implementation should be followed up within 90 days of CAP acceptance. Although TC 
initially advised West Wind on 12 December 2016 that it would conduct on-site verification 
within 90 days, this verification did not happen as planned. Some of the 2016 assessment 
CAPs were verified by TC in April 2017; however, the majority of CAPs were still open at the 
time of the occurrence, almost 1 year after the CAP acceptance dates. 
This means that CAP verification was approximately 9 months overdue at the time of the 
accident. Therefore, TC’s management of West Wind’s CAPs following the 2016 assessment 
was not in accordance with its policies. SI SUR-001 recommends a risk assessment be 
conducted if CAP verification is going to take longer than 90 days. TC did not follow this 
recommended procedure; therefore, regional TC management did not have a clear 
understanding of the risk of allowing West Wind to continue operating under EM. 
SI SUR-001 states that, if CAP implementation will take longer than 12 months, the matter 
must be referred to both regional management and the National Civil Aviation Management 
Executive (NCAMX). However, it was not in this case, and the decisions related to the 
oversight of West Wind remained primarily at the regional level. As a result, the regional TC 
office did not have the benefit of national-level decision-making support to ensure that 
actions taken following the 2016 assessment were consistent with national-level policies.
By not adhering to CAP verification policies and procedures following the 2016 assessment, 
TC was unable to ensure that the unsafe conditions that were identified during the 
assessment were being rectified. 
2.7.2.4 Conduct of the enhanced monitoring following 2016 assessment
The goal of placing a company under EM is to return the company to a state of regulatory 
compliance and to confirm that the necessary systems are in place to ensure ongoing 
compliance. To help ensure the effective use of EM, and a standardized approach, TC has 
published national-level EM policies and procedures. These are found primarily in SI SUR￾002; however, EM is referenced in a number of other TC documents. 
The investigation discovered several instances in which TC deviated from these policies and 
procedures, adopting an ad hoc approach to the EM of West Wind. For example, a critical 
component to the success of EM is the production of a focused EM surveillance plan (as 
required by SI SUR-002). This plan should clearly define EM team roles and responsibilities, 
conditions for EM termination, and timelines for the verification period and terminating 
PVI. There is no record of an EM surveillance plan for West Wind being prepared or 
approved by the regulator.
The absence of a plan resulted in there being no clear definition of the scope, team roles and 
responsibilities, EM activities, timeframe, or the conditions that needed to be met to 
terminate EM. Instead, the regulator selected a prolonged open-ended period of EM with no 
clear timeline or conditions for exit. This absence of direction and focus likely contributed  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 167
to unsafe conditions persisting for an extended period—almost 12 months—before the 
accident.
Finding as to risk
If the regulator does not create and follow a plan for EM, as required by its internal 
procedures, there is a risk that the EM will be ineffective in helping return companies to 
regulatory compliance. 
2.7.2.5 Conclusion
Finding: Other
TC’s inconsistent application of its own policies and procedures for the 2016 assessment
and post-assessment CAP verifications, as well as the ad hoc approach to EM, resulted in 
ineffective oversight of an operator that had a history of system-level (i.e., SMS) and 
systemic (e.g., operational control) non-compliance issues. 
Rather than taking immediate action to address the identified non-compliance issues, TC 
instead selected a prolonged, open-ended period of EM, which proved ineffective at 
returning West Wind to a state of compliance. 
By contrast, after the accident, TC conducted a reactive PI, which identified several 
significant areas of non-compliance. In addition, the OAB was convened to review the 
results of the post-occurrence PI and to recommend action, which resulted in the issuance 
of an immediate notice of suspension to West Wind. This timely OAB engagement was 
effective, but it was not consistent with the actions taken following the 2016 assessment.
Finding as to risk
If the application of TC’s surveillance policies and procedures is inconsistent, there is a risk 
that resulting oversight will not ensure that operators are able to effectively manage the 
safety of their operations.
2.7.3 Policies and procedures for Transport Canada inspectors 
TC inspectors rely on a variety of national-level policy documents and staff instructions to 
help them make decisions and conduct surveillance activities. To ensure the correct and 
consistent application of TC’s surveillance procedures, relevant information must be easily 
accessible, clear, and concise. In addition, inspectors must be made aware, in a timely 
manner, of newly issued or amended publications. 
The investigation noted a number of variances and potential for different interpretations in 
TC’s policy documents and instructions. In some instances, inspectors were unaware of 
newly issued or amended documents and instructions that are critical to their surveillance 
duties. 
Some documents overlap with others, yet do not reference the other document. For 
example, SI SUR-001 and SI SUR-029 both contain instructions for enforcement action; 
however, neither references the other. Topics such as EM and CAP procedures span 
multiple documents. 

168 | TRANSPORTATION SAFETY BOARD OF CANADA
The guidance for EM provided to regional personnel was largely in text format, and did not 
include clear decision-making or planning tools such as flow charts, timeline templates, or 
specific checklists to follow to ensure that EM was conducted in accordance with national 
policy.
There is no process to ensure that TC inspectors review recently issued or amended 
publications. Instead, the onus is placed on the inspector to review these documents. As a 
result, TC management does not have a process in place to ensure that inspectors are 
familiar with the current policies and procedures in effect. 
The combination of these factors increases the complexity of regional inspectors’ day-to￾day responsibilities and could contribute to the inconsistent application of regulatory 
oversight. Instead of a single reference document outlining each aspect of their job, 
inspectors must often review multiple, overlapping documents that are subject to change at 
any time. 
This occurrence highlights the risk posed by this situation, as regional inspectors were 
unaware of critical guidance (i.e., IPB 2016-04) that directed the most appropriate course of 
action for West Wind following the 2016 assessment. Instead, the regional inspectors acted 
on their understanding at the time when deciding how to proceed with West Wind.
Finding as to risk
If TC’s oversight guidance material for its inspectors is distributed among several different 
documents, and TC does not ensure that amendments to this guidance are received and 
understood, inspectors may not follow the latest guidance, and as a result, will not achieve 
the intended safety objectives.
2.8 West Wind safety management system
2.8.1 West Wind safety management and safety culture
While transportation companies have a responsibility to manage safety risks in their 
operations, compliance with regulations can provide only a baseline level of safety. 
When implemented properly, SMS enables companies to manage risk effectively and make 
operations safer. However, for SMS to be effective, it must be supported by a positive safety 
culture—one that starts at the top of the company with clearly established philosophies, 
policies, and procedures. There must be alignment between these and practices (4 Ps). 
Practices give an indication of the effectiveness of the procedures, policies, and the 
philosophies. They can also help identify gaps. 
This occurrence involved a CARs Subpart 705 operator with an SMS assessed and accepted 
by TC; however, some of its SMS-related activities did not achieve the intended level of 
safety. These activities, which are a measure of West Wind’s safety culture, reflected a 
misalignment between the 4 Ps, as these actions were not being conducted in accordance 
with company procedures, formal policies (including regulations), or the company’s stated 
higher-level goal of safe operations.  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 169
For example, in 2014, the company had developed informal policies related to operations 
on the narrow runways at CZFD and Wollaston Lake Airport (CZWL). However, at the time 
of the accident—3 years later—these policies still had not been incorporated into the 
company’s operations manual. Although not directly related to this accident, this slow 
action shows a tolerance for practices that are outside of established policy or procedure.
Similarly, in 2014, the day before commencing operations at CZFD, the company closed off a 
risk assessment regarding ATR 42 operations into CZFD and CZWL, although it was 
incomplete and was unable to identify several operational threats, such as ground icing, that 
flight crews would be expected to manage when flying into these locations. As a result, the 
company did not have an accurate understanding of the risks associated with operating out 
of CZFD in the winter months without adequate de-icing equipment. 
In the years before the accident, West Wind’s safety culture had progressively become less 
effective, likely due, in part, to inconsistent leadership. Since 2010, there had been 
considerable management personnel turnover at the company, particularly in the positions 
of Director of Flight Operations (DFO) and Subpart 705 Chief Pilot. In December 2016, to 
address issues raised in TC’s 2016 assessment, the DFO absorbed the roles and 
responsibilities of both the Director of Regulatory Standards and Compliance and the 
Subpart 705 Chief Pilot. Although this was intended to be a temporary fix, it remained that 
way for almost 1 year, ending 1 month before the accident. 
The increased workload of this arrangement was substantial and likely reduced the DFO’s 
capacity to adequately provide operational control and maintain compliance with all 
regulations. This resulted in a misalignment of the 4 Ps within the organization, the general 
acceptance of unsafe practices, and an inability to detect and rectify systemic non￾compliance issues—factors that all indicate a degraded safety culture.
From a broader perspective, the TSB investigation determined that this acceptance of 
unsafe practices extended beyond West Wind. The TSB’s questionnaire revealed that other 
pilots operating at remote locations also take off with contaminated critical aircraft 
surfaces, even though this practice is contrary to established regulations and represents a 
serious risk to transportation safety.
Finding as to risk
If a company’s safety culture tolerates unsafe practices, there is a risk that these practices 
will continue and become a company norm. 
2.8.2 Safety risk management
One of the 4 components of an effective SMS is safety risk management: proactively 
identifying hazards, assessing risk, implementing risk mitigation strategies, and evaluating 
their effectiveness. A detailed, systematic risk management process gives companies a 
better understanding of the challenges to expect in a particular operating environment, 
resulting in higher levels of safety performance.  

170 | TRANSPORTATION SAFETY BOARD OF CANADA
Hazard identification is the first step in safety risk management. When embarking on a new 
operation, there are a number of potential hazard areas to consider. This is particularly 
important for challenging operations, such as those conducted into remote locations with 
limited support infrastructure. 
In an effort to address this risk, West Wind opened a risk assessment in May 2014 to look 
into the potential hazards with commencing new operations into CZFD. The assessment was 
closed on 11 September 2014, the day before commencing ATR 42 operations into CZFD.
Some of the hazards with operating into remote locations are well known, such as a lack of 
weather reporting services, a lack of flight-following services, and even the absence of de￾icing equipment. However, companies assessing the risk of this type of operation should 
also attempt to identify, in a systematic manner, less obvious hazards. This can be 
accomplished by reviewing hazard reports, conducting safety surveys, or using knowledge 
from subject-matter experts who have additional insight on the hazards associated with a 
particular operation. 
In this occurrence, West Wind’s safety risk management process did not identify or explore 
several hazards associated with operating at CZFD and CZWL. Instead, West Wind identified 
the hazard as an “ORM [operational risk management] exercise for proposed operations 
into Fond du Lac and Wollison [sic] Lake with the ATR 42.” 
Using this as the identified hazard, the company determined the probability to be unlikely 
and the severity to be major. This hazard statement was imprecise and did not accurately
state the hazards, which would have made it difficult to accurately describe and assess the 
risk level of the proposed operation. 
It is likely that West Wind, as an organization, did not have a thorough understanding of risk 
management practices and, therefore, did not have the ability to accurately complete the 
risk management process. 
Another important aspect of safety risk management is the consideration of underlying 
factors that may themselves be hazards, or may influence other identified hazards. In the 
case of assessing operations into these remote areas, it may have been possible to identify 
potential internal or external pressure that could influence pilot decision making, resulting 
in a hazardous outcome; however, the assessment did not identify this pressure.
West Wind’s risk assessment did not take into account these potential influences on pilots, 
the self-described “can do” pilot subculture, or the lack of support to assist pilot decision
making. As a result, West Wind did not have a complete understanding of the hazards that 
existed in 2014 and persisted until the occurrence.
Once hazards are well defined, organizations must then assess the risk and determine what, 
if any, risk controls can be implemented to reduce risk to as low as reasonably practicable. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 171
Finding as to risk
If organizations do not adequately identify hazards and analyze risks, potential mitigation 
methods can be overlooked, increasing the risk of an adverse consequence.
This is what occurred at West Wind during its risk assessment of the operations into CZFD 
and CZWL. Because the company did not accurately identify the hazards, it was therefore 
unable to apply adequate risk control measures.
Finding as to causes and contributing factors
When West Wind commenced operations into CZFD in 2014, no effective risk controls were 
in place to mitigate the potential hazard of ground icing at CZFD. 
If the hazards had been properly identified during the 2014 risk assessment, the company 
could have reinforced existing policies regarding the clean aircraft concept, or provided 
more specific guidance to aid pilot decision making for ground icing at locations without 
proper de-icing equipment. 
Because of the dynamic nature of commercial aviation, it is important from a safety risk 
management standpoint that organizations periodically review operational decisions to 
ensure that previous assumptions remain valid. In the case of the CZFD risk assessment, 
after it was complete, the company did not revisit it or challenge its original assumptions. 
When concerns about the insufficient de-icing equipment were raised by the occurrence 
captain 1 month after the risk assessment was closed, the company did not take any formal 
action, such as reopening the risk assessment or amending the SOPs. Instead, it issued a 
memorandum stating that the risk was acceptable and that the company recognized it 
would result in approximately 4% of flights being cancelled or delayed. In addition to this 
memorandum, the company distributed an informal rule by word-of-mouth that these 
remote locations should be avoided entirely if icing was known to be an issue.
Finding as to risk
If mitigations that are determined following risk assessments are not formalized and 
properly disseminated, they may not be widely implemented in a sustained fashion, 
increasing the risk of accidents. 

172 | TRANSPORTATION SAFETY BOARD OF CANADA
3.0 FINDINGS
3.1 Findings as to causes and contributing factors
These are conditions, acts or safety deficiencies that were found to have caused or contributed to 
this occurrence.
1. When West Wind commenced operations into Fond-du-Lac Airport (CZFD) in 2014, no 
effective risk controls were in place to mitigate the potential hazard of ground icing at 
CZFD.
2. Although both the flight crew and the dispatcher were aware of the forecast ground 
icing, the decision was made to continue with the day’s planned route to several remote 
airports that had insufficient de-icing facilities.
3. Although the aircraft’s ice-protection systems were activated on the approach to CZFD, 
the aircraft’s de-icing boots were not designed to shed all of the ice that can accumulate, 
and the anti-icing systems did not prevent ice accumulation on unprotected surfaces. As 
a result, some residual ice began to accumulate on the aircraft.
4. Although the flight crew were aware of the ice, there were no handling anomalies noted 
on the approach. Consequently, the crew likely did not assess that the residual ice was
severe enough to have a significant effect on aircraft performance. Subsequently, 
without any further discussion about the icing, the crew continued the approach and 
landed at CZFD.
5. Weather conditions on the ground were conducive to ice or frost formation, and this, 
combined with the nucleation sites provided by the residual mixed ice on the aircraft, 
resulted in the formation of additional ice or frost on the aircraft’s critical surfaces.
6. Because the available inspection equipment was inadequate, the first officer’s ice 
inspection consisted only of walking around the aircraft on a dimly lit apron, without a 
flashlight, and looking at the left wing from the top of the stairs at the left rear entry 
door (L2). As a result, the full extent of the residual ice and ongoing accretion was 
unknown to the flight crew.
7. Departing from remote airports, such as CZFD, with some amount of surface 
contamination on the aircraft’s critical surfaces, had become common practice, in part 
due to the inadequacy of de-icing equipment or services at these locations. The past 
success of these adaptations resulted in the unsafe practice becoming normalized and 
this normalization influenced the flight crew’s decision to depart.
8. Although the flight crew were aware of icing on the aircraft’s critical surfaces, they 
decided that the occurrence departure could be accomplished safely. Their decision to 
continue with the original plan to depart was influenced by continuation bias, as they  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 173
perceived the initial and sustained cues that supported their plan as more compelling 
than the later cues that suggested another course of action. 
9. As a result of the ice that remained on the aircraft following the approach and the 
additional ice that had accreted during the ground stop, the aircraft’s drag was 
increased by 58% and its lift was decreased by 25% during the takeoff.
10. During the takeoff, despite the degraded performance, the aircraft initially climbed; 
however, immediately after lift off, the aircraft began to roll to the left without any pilot 
input. This roll was as a result of asymmetric lift distribution due to uneven ice 
contamination on the aircraft.
11. Following the uncommanded roll, the captain reacted as if the aircraft was an 
uncontaminated ATR 42, with the expectation of normal handling qualities and dynamic 
response characteristics; however, due to the contamination, the aircraft had 
diminished roll damping resulting in unexpected handling qualities and dynamic 
response. 
12. Although the investigation determined the ailerons had sufficient roll control authority 
to counteract the asymmetric lift, due to the unexpected handling qualities and dynamic 
response, the roll disturbance developed into an oscillation with growing magnitude
and control in the roll axis was lost.
13. This loss of control in the roll axis, which corresponds with the known risks associated 
with taking off with ice contamination, ultimately led to the aircraft colliding with 
terrain. 
14. The aircraft collided with the ground in relatively level pitch, with a bank angle of 30° 
left. As a result of the sudden vertical deceleration upon contact with the ground, the 
aircraft suffered significant damage, which varied in severity at different locations on 
the aircraft because of the impact angle and the variability in structural design.
15. The design standards for transport category aircraft in effect at the time the ATR 42 was 
certified did not specify minimum loads that a fuselage structure must be able to 
tolerate and remain survivable, or minimum loads for fuselage impact energy 
absorption. As a result, the ATR 42 was not designed with these crashworthy principles 
in mind.
16. On impact, the induced acceleration was not attenuated because the landing gear 
housing did not deform. This unattenuated acceleration resulted in a large inertial load 
from the wing, causing the wing support structure to fail and the wing to collapse into 
the cabin.
17. The reduced survivable space between the floor above the main landing gear and the 
collapsed upper fuselage caused crushing injuries, such as major head, body, and leg  

174 | TRANSPORTATION SAFETY BOARD OF CANADA
trauma, to passengers in the middle-forward left section of the aircraft. Of the 
3 passengers in this area, 2 experienced serious life-changing injuries, and 1 passenger 
died.
18. The collapse of part of the floor structure compromised the restraint systems, limiting 
the protection afforded to the occupants when they were experiencing vertical, 
longitudinal, and lateral forces. This resulted in serious velocity-related injuries and 
impeded their ability to take post-impact survival actions in a timely manner.
19. Most passengers in this occurrence did not brace before impact. Because their torsos 
were unrestrained, they received injuries consistent with jackknifing and flailing, such 
as hitting the seat in front of them.
20. Given that regulations requiring the use of child-restraint systems have yet to be 
implemented, the aircraft was not equipped with these devices. As a result, the infant 
passenger was unrestrained and received flail and crushing injuries.
21. As a result of unapproved repairs, the flight attendant seat failed on impact, resulting in 
injuries that impeded her ability to perform evacuation and survival actions in a timely 
manner.
3.2 Findings as to risk
These are conditions, unsafe acts or safety deficiencies that were found not to be a factor in this 
occurrence but could have adverse consequences in future occurrences. 
1. If weather forecasting guidance does not allow for the forecasting of icing that can occur 
in the absence of precipitation or fog, there is an increased risk that pilots will not have 
advance warning of foreseeable ground icing conditions.
2. If ground icing operations programs do not clearly define a procedure to identify 
ground icing conditions, flight crews may not initiate inspection and de-icing
procedures, increasing the risk of aircraft taking off with contaminated surfaces.
3. If guidance material that requires the inspection of aircraft surfaces that are not visible 
from the ground does not detail a procedure to conduct this inspection, there is a risk 
that the inspection will not be completed, and surface contamination will go undetected.
4. If staff who are aware of deficiencies in de-icing procedures, or the availability of 
equipment, do not report these hazards through the company’s safety management 
system, there is a risk that the hazards will not be documented, assessed, and mitigated.
5. When a trans-cockpit authority gradient is relatively flat, communications may be less 
effective and pilots may make erroneous assumptions concerning the other pilot’s 
situational awareness and decision-making, increasing the risk that hazards to flight 
will not be identified and addressed by the crew. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 175
6. Although threat and error management briefings are helpful, if they are relied upon to 
mitigate threats or errors that are systemic adaptations, there is a risk that the hazards 
will continue, especially if the threat itself is non-compliance with the mitigation 
method. 
7. If adequate de-icing equipment is unavailable, especially at locations with routine 
operations, there is a risk that, if ice is detected, the perceived pressure from causing 
extensive delays may lead flight crews to make adaptations to the clean aircraft concept 
and depart with contamination on the aircraft’s critical surfaces. 
8. Until actions are implemented to address the availability of anti-icing and de-icing 
equipment (TSB Recommendation A18-02) and compliance (TSB Recommendation 
A18-03), there remains a persistent risk that pilots will not comply with the clean 
aircraft concept and will continue to take off with contaminated aircraft.
9. If the guidance provided to pilots to help them determine when to select take-off icing 
speeds is not clear and well-defined, flight crews may select a take-off speed or 
operating weight that will result in the aircraft being unable to meet the minimum 
performance requirements set by certification standards, thereby increasing the risk of 
an accident. 
10. If flight crews do not apply the take-off performance calculation penalties required for 
contaminated or unpaved runways, they might operate at take-off weights or on runway 
lengths that do not meet their aircraft’s capabilities, increasing the risk of a runway 
excursion or accident.
11. When the wing collapsed, the integral fuel became uncontained and leaked out, 
significantly increasing the risk of a post-impact fire at a time when passengers were 
unable to evacuate. 
12. Following the wing collapse, the leaked fuel entered the survivable space, and with the 
outside temperature of approximately −10 °C, the passengers who were soaked in fuel 
faced an increased risk of hypothermia.
13. The collapse also resulted in structural and terrain hazards entering the cabin 
survivable space. These intrusions increased the risk of injuries for those occupants 
flailing in their seats during the accident sequence, and also to evacuating passengers 
who had to climb through the cabin, over seats and hazards, to evacuate the aircraft.
14. As shown in this occurrence, on aircraft certified to older standards, there is a risk that 
displacement of cargo restraint systems and cabin partitions that are positioned 
adjacent to an evacuation route could impede the evacuation route for survivors.  

176 | TRANSPORTATION SAFETY BOARD OF CANADA
15. If company risk profiles maintained by the regulator are not up to date and accurate, 
changes in a company’s risk profile may go undetected and surveillance activities might 
be reduced, allowing unsafe conditions to develop or persist.
16. If the regulator does not create and follow a plan for enhanced monitoring, as required 
by its internal procedures, there is a risk that the enhanced monitoring will be 
ineffective in helping return companies to regulatory compliance.
17. If the application of Transport Canada’s surveillance policies and procedures is 
inconsistent, there is a risk that resulting oversight will not ensure that operators are 
able to effectively manage the safety of their operations.
18. If Transport Canada’s oversight guidance material for its inspectors is distributed 
among several different documents, and Transport Canada does not ensure that 
amendments to this guidance are received and understood, inspectors may not follow 
the latest guidance, and as a result, will not achieve the intended safety objectives.
19. If a company’s safety culture tolerates unsafe practices, there is a risk that these 
practices will continue and become a company norm. 
20. If organizations do not adequately identify hazards and analyze risks, potential 
mitigation methods can be overlooked, increasing the risk of an adverse consequence.
21. If mitigations that are determined following risk assessments are not formalized and 
properly disseminated, they may not be widely implemented in a sustained fashion, 
increasing the risk of accidents.
3.3 Other findings
These items could enhance safety, resolve an issue of controversy, or provide a data point for 
future safety studies.
1. Transport Canada’s inconsistent application of its own policies and procedures for the 
2016 assessment and post-assessment corrective action plan verifications, as well as 
the ad hoc approach to enhanced monitoring, resulted in ineffective oversight of an 
operator that had a history of system-level (i.e., safety management system) and 
systemic (e.g., operational control) non-compliance issues. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 177
4.0 SAFETY ACTION
4.1 Safety action taken
4.1.1 Transportation Safety Board of Canada
4.1.1.1 TSB Recommendation A18-02 on access to adequate equipment
The duration of cold weather and icing conditions varies widely across Canada. Many 
remote northern airports have an icing season of 10 months or more. Icing conditions can 
be both severe and persistent.
Thousands of flights take off every year from remote northern airports. Some airports serve 
as hubs, experience higher traffic volumes, and may have better equipment.
The risks of adverse consequences likely vary from airport to airport. Identifying high-risk 
locations for immediate mitigation has the potential to quickly reduce the likelihood of 
aircraft taking off with frost, ice, or snow adhering to any critical surface at those locations.
Transport Canada (TC), air operators, and airport authorities have the capacity to identify 
high-risk locations, analyze them for hazards and risks, and take mitigating action.
Therefore, in December 2018, the Board recommended that
the Department of Transport collaborate with air operators and airport 
authorities to identify locations where there is inadequate de-icing and anti￾icing equipment and take urgent action to ensure that the proper equipment 
is available to reduce the likelihood of aircraft taking off with contaminated 
critical surfaces.
TSB Recommendation A18-02
In its response (September 2020) and update (November 2020) to this recommendation, 
TC indicated that it had reached out to stakeholders, created working groups, and held 
discussions to address the safety issues identified in this recommendation. The COVID-19 
pandemic has presented many challenges to the industry, which have delayed the 
development of concrete actions to ensure proper de-icing and anti-icing equipment is 
available to reduce the likelihood of aircraft taking off with contaminated critical surfaces.
Until steps are taken to ensure proper de-icing and anti-icing equipment is available, the 
risks associated with the safety deficiency identified in Recommendation A18-02 will 
continue to exist. 
Therefore, in December 2020, the Board considered the response to Recommendation A18-
02 to show Satisfactory Intent.
284
 284 TSB Recommendation A18-02: De-icing and anti-icing equipment, at 
https://www.tsb.gc.ca/eng/recommandations-recommendations/aviation/2018/rec-a1802.html (last accessed 
08 February 2021). 

178 | TRANSPORTATION SAFETY BOARD OF CANADA
4.1.1.2 TSB Recommendation A18-03 on compliance with the clean aircraft concept
The duration of cold weather and icing conditions varies widely across Canada. Many 
remote northern airports have an icing season of 10 months or more. Icing conditions can 
be both severe and persistent.
Thousands of flights take off every year from remote northern airports. Some airports serve 
as hubs, experience higher traffic volumes, and may have better equipment.
The absence of adequate equipment increases the likelihood that pilots will conduct a 
takeoff in an aircraft that has frost, ice, or snow adhering to any of its critical surfaces. 
Additionally, in the absence of adverse consequences, taking off with contamination on 
critical surfaces is a deviation that has become normalized. Therefore, providing adequate 
de-icing and anti-icing equipment may not be sufficient to reduce the likelihood of aircraft 
taking off with contaminated critical surfaces.
Some of the current defences used by the Canadian air transportation system to prevent 
aircraft from taking off with frost, ice, or snow adhering to any critical surface are less than 
adequate. Takeoffs with contaminated critical surfaces occur in substantial numbers across 
the spectrum of aircraft and operating categories at remote northern airports.
Non-compliance with Canadian Aviation Regulations subsection 602.11(2), flight crew 
operating manuals, company operations manuals, and company standard operating 
procedures can be a single point of failure of defence framework. To mitigate this, 
Transport Canada and air operators must take urgent action to ensure better compliance.
Organizations can audit equipment (to inspect, de-ice, and anti-ice aircraft), policies (such 
as ground icing operations programs and contingencies for situations where resources are 
not available), training (for pilots and ground staff), and operations (procedures, 
compliance, deviations). Air operators could incorporate questions in before-start and 
before-takeoff checklists with a requirement for a clean aircraft or a mitigation response 
from the pilot-in-command.
Accidents related to contaminated aircraft will continue to occur until the industry and the 
regulator approach the issue as systemic and take action to eliminate underlying factors 
that can negatively affect pilot compliance.
Therefore, in December 2018, the Board recommended that
the Department of Transport and air operators take action to increase 
compliance with Canadian Aviation Regulations subsection 602.11(2) and 
reduce the likelihood of aircraft taking off with contaminated critical 
surfaces.
TSB Recommendation A18-03
In its response (September 2020) and update (November 2020) to this recommendation,
TC indicated that it had reached out to stakeholders, and that educational and awareness 
material have been made available regarding the hazards of aircraft taking off with 
contaminated critical surfaces. The COVID-19 pandemic has presented challenges to TC and 
prevented most of its planned targeted inspections aimed at increasing compliance  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 179
with CARs subsection 602.11(2). Increased compliance with the regulation would reduce 
the likelihood of aircraft taking off with contaminated critical surfaces.
Until more robust actions are taken to increase compliance with CARs subsection 602.11(2), 
the risks associated with the safety deficiency identified in Recommendation A18-03 will 
continue to exist.
Therefore, in December 2020, the Board considered the response to Recommendation A18-
03 to show Satisfactory Intent.
285
4.1.2 West Wind Aviation L.P.
4.1.2.1 Risk assessments
Since the occurrence, West Wind has implemented new risk assessment requirements. Risk 
assessments are now completed for new procedures, changes in managerial staff, and for all 
airports where the company normally operates and for charter destinations. All 
organizational changes of staff holding a regulatory role are documented through the safety 
management system to allow for risk assessments, including follow-up and audits to 
confirm information has been disseminated and procedures are followed. The risk 
assessments for airports include an overview of all services and facilities available, 
including de-icing capabilities.
The West Wind Board of Directors implemented a Safety, Operations and Customer 
Experience (SOCE) Committee that provides corporate oversight of the safety culture and 
safety matters. 
4.1.2.2 Equipment
West Wind has equipped each of its scheduled service and regular charter destinations with 
equipment capable of inspecting and de-icing all of the operator’s aircraft types. Personnel 
at each of theses locations are required to complete a daily de-ice equipment inspection to 
ensure the serviceability of the equipment and an annual de-ice equipment quality 
assurance audit is completed at the beginning of winter operations. All flight crews are also 
provided high-power, light-emitting diode flashlights to facilitate aircraft surface 
inspections.
4.1.2.3 Written guidance
Written guidance requires that flights dispatched to airports with insufficient de-icing 
capabilities adhere to the following requirements:
1. Self-dispatch is not authorized
 285 TSB Recommendation A18-03: Compliance with Canadian Aviation Regulations subsection 602.11(2), at 
https://www.tsb.gc.ca/eng/recommandations-recommendations/aviation/2018/rec-a1803.html (last accessed 
08 February 2021). 

180 | TRANSPORTATION SAFETY BOARD OF CANADA
2. If active icing conditions on the ground or active frost are known or forecast 
dispatch is not authorized.
3. No flight will be dispatched to these locations without authorization from 
the Operations Manager or delegate on a daily basis.
4. The following procedure must be followed: 
a. With reference to the applicable GFA Icing, Turbulence & Freezing 
level:
i. If the forecast freezing level is below 5000’ within 30 nm radius of 
the destination, using GFA scale, of the destination the following 
procedure must be applied:
ii. The flight path must ensure that no icing conditions will be 
encountered from departure to destination. 
iii. No known or forecast icing conditions or precipitation within 30 nm 
radius of the destination airport at the planned arrival time 
b. The alternate airport must have at least Type I de-icing available. 
i. An alternate that has been verified to have the required level of 
service but is not listed on the chart may be used. The PIC and 
dispatch must agree on the level of service. 
c. Prior to landing: flight crew must do a visual inspection of the 
representative surfaces to ensure that no icing condition has been 
encountered and the aircraft is free of any ice. 
d. If icing has been encountered, flight crew must divert to alternate 
airport. 
e. If surface temps are forecast to be positive and it is reasonable to expect 
any residual contamination to melt or sublimate a landing may be 
conducted. On the ground, if the aircraft is contaminated with ice, the 
flight crew must call the Operations Manager or delegate for appropriate 
course of action. GFA weather prediction will be confirmed by using a 
remote weather station. 
i. Stony Rapids, CYSF will be used for: 
1. Uranium City, CYBE 
ii. For any aerodrome that is not listed, the nearest suitable weather 
station should be used for cross-referencing as applicable. 
iii. If there is a discrepancy between the GFA and the remote weather 
station, the most severe condition will be considered in effect. 
iv. The PIC and Dispatch must agree on the current weather.286
 286 West Wind, Winter Operations Briefing 2020/2021 Rev #1, 1 November 2020 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 181
4.1.2.4 Training
West Wind has made the following amendments to its training programs:
• Pilot ATR simulator training has been expanded from 1 simulator module in icing 
conditions to 2, and additional time is spent on cold weather operations during 
ground school training.
• Pilot ATR simulator initial and recurrent training now includes a scripted severe 
icing scenario with reduced controllability.
• Initial and recurrent pilot training includes contaminated runway performance 
requirements and the use of icing speeds and has been incorporated into the 
simulator training.
• Flight crews are trained to use ATR-approved procedures from the manufacturer’s 
Flight Crew Operating Manual for aircraft contamination inspections and the need 
for additional inspections if there is any doubt about aircraft contamination.
• Flight attendants are trained that in the event of unusual attitudes during a critical 
phase of flight, such as takeoff or landing, they are permitted to initiate brace signals 
at their own discretion.
• Crew resource management (CRM) training includes the concept that systemic 
adaptations lead to noncompliance and must not be incorporated into daily 
operations.
4.1.2.5 Maintenance
West Wind has implemented new procedures when contracting maintenance, including 
auditing the repair station, reviewing repair data and comparing against published material 
(such as the Component Maintenance Manuals), and conducting oversight during heavy 
checks.
This report concludes the Transportation Safety Board of Canada’s investigation into this 
occurrence. The Board authorized the release of this report on 02 June 2021. It was 
officially released on DD Month 20YY.
Visit the Transportation Safety Board of Canada’s website (www.tsb.gc.ca) for information 
about the TSB and its products and services. You will also find the Watchlist, which 
identifies the key safety issues that need to be addressed to make Canada’s transportation 
system even safer. In each case, the TSB has found that actions taken to date are 
inadequate, and that industry and regulators need to take additional concrete measures to 
eliminate the risks. 

182 | TRANSPORTATION SAFETY BOARD OF CANADA
APPENDICES
Appendix A – Transport Canada Civil Aviation’s Safety Management System
Framework (components and elements)
Component Element
Safety Management Plan 1.1 Safety Policy
1.2 Non-Punitive Safety Reporting Policy
1.3 Roles, Responsibilities
1.4 Communications
1.5 Safety Planning
1.6 Performance Management
1.7 Management Review
Documentation 2.1 Identification and Maintenance of Applicable Regulations 
2.2 SMS Documentation 
2.3 Records Management
Safety Oversight 3.1 Reactive Processes – Reporting 
3.2 Proactive Processes – Hazard Identification 
3.3 Investigation and Analysis 
3.4 Risk Management
Training 4.1 Training, Awareness and Competence
Quality Assurance 5.1 Quality Assurance
Emergency Preparedness 6.1 Emergency Preparedness and Response 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 183
Appendix B – Compliance summary of West Wind assessment made by 
Transport Canada Civil Aviation in September 2016
Component 1. Safety Management Plan
1.1 Safety Policy Not assessed during on-site
activities
Further review to be conducted by Transport 
Canada.
1.2 Non-Punitive Safety 
Reporting Policy
Compliant Regulatory requirements have been met.
1.3 Roles, Responsibilities Not assessed during on-site
activities
Further review to be conducted by Transport 
Canada.
1.4 Communications Partially implemented Information is established and maintained 
through a suitable medium.
Partially documented, 
partially implemented
There is a process for the dissemination of 
safety information throughout the 
organization and a means of monitoring 
the effectiveness of this process.
1.5 Safety Planning Partially implemented Objectives and goals are consistent with the 
safety policy, and their attainment is 
measurable.
Partially implemented Safety objectives and goals are reviewed 
and updated periodically.
Partially implemented Safety objectives and goals are 
documented and publicized.
1.6 Performance 
Management
Not assessed during on-site
activities
Further review to be conducted by Transport 
Canada.
1.7 Management Review Not assessed during on-site
activities
Further review to be conducted by Transport 
Canada.
Component 2. Documentation
2.1 Identification and
Maintenance of 
Applicable CARs
[Canadian Aviation 
Regulations]
Partially implemented The organization has established, 
maintained, and adhered to documentation 
requirements applicable to the certificate(s) 
held, as required by the CARs.
2.2 SMS [Safety 
Management System] 
Documentation
Partially implemented There are acceptable means of 
documentation, including but not limited 
to, organizational charts, job descriptions, 
and other descriptive written material that 
defines and clearly delineates the system of 
authority and responsibility within the
organization for ensuring safe operation.
Partially implemented The organization has a process to identify 
changes within the organization that could 
affect company documentation.
2.3 Record Management Compliant Regulatory requirements have been met. 

184 | TRANSPORTATION SAFETY BOARD OF CANADA
Component 3. Safety Oversight
3.1 Reactive Processes –
Reporting
Partially implemented The organization has a process or system 
that provides for the capture of internal 
information, including hazards, incidents 
and accidents, and other data relevant to 
SMS.
3.2 Proactive Processes –
Reporting
Partially implemented There is a feedback process to notify 
contributors that their proactive reports 
have been received and to share the end 
result of the analysis.
Partially implemented Corrective actions are generated and 
implemented in response to hazard 
analysis.
Partially implemented The organization will develop a safety risk 
profile that prioritizes hazards listed on the 
hazard registry.
3.3 Investigating and 
Analysis
Partially implemented There is evidence that the organization has 
made every effort to complete the 
investigation and analysis process in the 
established timeframe.
3.4 Risk Management Partially implemented Corrective actions, resulting from the risk 
assessment, including timelines, are 
documented.
Component 4. Training, Awareness, and Competence
4.1 Training, Awareness,
and Competence
Not documented, not 
implemented
Regulatory requirements have not been 
met.
Component 5. Quality Assurance
5.1 Quality Assurance Partially implemented There is an operationally independent audit 
function with the authority required to carry 
out an effective internal evaluation 
program.
Partially implemented The organization conducts reviews and 
audits of its processes, procedures, 
analyses, inspections, and training.
Partially implemented The quality assurance system covers all 
functions defined within the certificate(s).
Component 6. Emergency Preparedness and Response
6.1 Emergency 
Preparedness and
Response
Compliant Regulatory requirements have been met. 

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Operational Control
Flight Training Program Not implemented Regulations, standards, and exemptions are 
periodically reviewed to ensure that the 
most current information is available.
Flight and Duty Times Not implemented Regulations, standards and exemptions are 
periodically reviewed to ensure that the 
most current information is available.
Type B Dispatch (Desk 
Monitor)
Compliant Regulatory requirements have been met. 

186 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix C – Findings from the 2016 assessment
The following is a summary of the findings from Transport Canada’s 2016 assessment287 of 
West Wind operations.
Finding Component/Element Classification
On-site 01288 Operational Control/Flight Training Program: Company failed to 
establish and maintain an ATR 42 training program in accordance with 
Commercial Air Services Standards (CASS) 725.124 (CARs [Canadian 
Aviation Regulations] 705.124 (l)(b)).
Examples cited: Several pilots were missing required training.
Major
On-site 02289 Operational Control/Flight Training Program: Company failed to 
establish and maintain an air taxi training program in accordance with 
CASS 723.98 (CARs 703.98 (1) (b)).
Examples cited: Several pilots were missing required training.
Major
On-site 03290 Operational Control/Flight Training Program: Company failed to 
establish and maintain a commuter training program in accordance 
with CASS 724.115 (CARs 704.115 (1) (b)).
Examples cited: Several pilots were missing required training.
Major
107-01 Documentation/Identification and Maintenance of Applicable 
Regulations: Company failed to establish, maintain, and adhere to 
documentation requirements applicable to the certificate held, as 
required by the CARs (CARs 107.02).
Examples cited:
Subpart 705 training program not approved by TC [Transport Canada];
Pilot training forms deficient; and
COM [Company Operations Manual] missing security procedures.
Major
700-01 Operational Control/Flight and Duty Times: The company failed to 
establish a system that effectively monitors rest periods for each of its 
flight crew members (CARs 700.14 (1)).
Examples cited: Errors found related to flight time, duty time, and rest 
time tracking system for some company pilots.
Major
704-01 Operational Control/Flight Training Program: The company chief pilot 
failed to ensure that required duties were carried out in accordance 
with CASS 724.07(2)(b)(ii) (CARs 704.02).
Examples cited:
The chief pilot failed to develop and implement all required approved 
training programs for the air operator flight crews, as documented in 
On-site Finding 03.
The chief pilot failed to supervise flight crews.
Major
 287 Transport Canada, Surveillance Report – West Wind Aviation, 12–23 September 2016, Finding Forms, 
RDIMS #12439289.
288 Transport Canada, Onsite Finding 01 West Wind Aviation, September 2016, RDIMS #12439264
289 Transport Canada, Onsite Finding 02 West Wind Aviation, September 2016, RDIMS #12439379.
290 Transport Canada, Onsite Finding 03 West Wind Aviation, September 2016, RDIMS #12439430. 

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705-01 Operational Control/Flight Training Program: The company operations 
manager failed to ensure that required duties were carried out in 
accordance with CASS 725.07(2)(e)(ii) (CARs 705.02).
Examples cited:
The operations manager failed to control operations, in that flight 
crews were allowed to use unapproved documents.
The operations managed failed to supervise and organize flight 
operations.
The operations manager failed to supervise and organize the training 
programs.
The operations manager failed to supervise the production and 
amendment of the COM, in that training programs were not updated in 
order to maintain compliance with the CASS.
The operations manager failed to ensure that the air operator's 
operations were conducted in accordance with current regulations, 
standards, and air operator policy, in the fact that the training program 
was missing elements of the standard.
The operations manager failed to ensure that crew scheduling complies 
with flight and duty time regulations.
The operations manager failed to ensure the qualifications of flight 
crews.
Major
705-02 Operational Control/ Flight Training Program: The Subpart 705 chief 
pilot failed to ensure that required duties were carried out in 
accordance with CASS 725.07(2)(b)(ii) (CAR 705.02).
Examples cited:
The chief pilot failed to develop all required approved training 
programs for the air operator ATR 42 flight crews, as documented in 
finding On-Site 01.
The chief pilot failed to implement all required approved training 
programs for the air operator, as ATR 42 flight crews were being trained 
using an unapproved training manual.
The chief pilot failed to supervise flight crews, as evidenced by the lack 
of document control in the use of uncontrolled flight training forms.
Major
706-01 Quality Assurance: West Wind did not have an operationally 
independent audit function with the authority required to carry out an 
internal evaluation program (CAR 706.07(5)).
Examples cited: West Wind failed to ensure objectivity in the company’s 
2015 quality assurance audit, as the audit was performed by the 
company’s SMS manager.
Moderate 

188 | TRANSPORTATION SAFETY BOARD OF CANADA
573-01 Quality Assurance: West Wind did not have an operationally 
independent audit function with the authority required to carry out an 
internal evaluation program (CAR 573.09).
Examples cited:
West Wind failed to ensure objectivity in the company’s 2015 quality 
assurance audit, as the audit was performed by the company’s SMS 
manager.
West Wind was unable to identify that the AMO [approved 
maintenance organization] certificate’s limitations did not reflect the 
privileges approved in the nature and scope of work in section 6 of the 
combined MPM/MCM [Maintenance Policy Manual/Maintenance 
Control Manual].
West Wind failed to identify the unavailability of a technical reference 
document that was noted as the root cause in a company SMS report.
Moderate 

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Appendix D – Surveillance interval matrix 
Source: CAD-SUR-008, Issue 02 (29 May 2012), with TSB annotations. 

190 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix E – West Wind National Aviation Safety Information Management 
System risk profile 

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196 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix F – West Wind safety management system reporting form 

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Appendix G – West Wind flowchart for safety reviews (28 June 2018) 

198 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix H – TSB investigations with findings related to regulatory 
oversight and safety management systems
TSB 
occurrence
number
Finding (finding type) Safety action taken 
(reported by 
Transport Canada)
A16A0041 If organizations do not use modern safety management practices 
and do not have a robust safety culture, then there is an increased 
risk that hazards will not be identified and mitigated. (Risk)
None reported.
A15P0217 Because the processes described in Helijet International Inc.’s, safety 
management system (SMS) were not being used effectively, the SMS 
did not help the company identify and mitigate the risks associated 
with its night medical evacuation operations. (Cause and 
Contributing)
At the time of the occurrence, there was a lack of resources and 
training dedicated to the company’s SMS, limiting its effectiveness in 
mitigating the risks in night operations. (Cause and Contributing)
If identified hazards are not captured by a company's SMS, they may 
go unaddressed, increasing the risk of accidents. (Risk)
None reported.
A15A0054 If organizations do not use modern safety management practices, 
then there is an increased risk that hazards will not be identified and 
risks will not be mitigated. (Risk)
If an organization’s safety culture does not fully promote the goals of 
a safety management system, then it is unlikely that it will be 
effective in reducing risk. (Risk)
None reported.
A15Q0120 Unless safety management systems are required, assessed, and 
monitored by Transport Canada in order to ensure continual 
improvement, there is an increased risk that companies will not be 
able to identify and effectively mitigate the hazards involved in their 
operations. (Risk)
None reported.
A14P0132 An understaffed management structure during organizational 
changes likely led to excessive workload for existing managers. This 
contributed to risks, contained within the standard operating 
procedures, not being addressed through the operator’s safety 
management system, resulting in continued aircraft operations below 
published minimum airspeed limitations. (Cause and Contributing)
If organizations do not maintain the necessary management 
resources to oversee effective safety management practices, long￾term efforts may dissipate, resulting in the risk of unsafe practices 
persisting in flight operations. (Risk)
None reported.
A14A0067 If Transport Canada does not adopt a balanced approach that 
combines thorough inspections for compliance with audits of safety 
management processes, unsafe operating practices may not be 
identified, thereby increasing the risk of accidents. (Risk)
None reported.
A13H0002 If identified regulatory surveillance intervals are not respected, then 
there is an increased likelihood that systemic deficiencies that could 
increase risk will go unidentified and unaddressed. (Risk)
If findings are overly general, it increases the scope of possible 
corrective actions and makes it more difficult for the regulator to 
assess whether the underlying deficiency is addressed through the 
corrective action plan, increasing the risk that safety deficiencies will 
remain unaddressed. (Risk)
None reported. 

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If Transport Canada does not take action to require operators to 
respect corrective action plan implementation timeframes, there is a 
risk that safety deficiencies will not be corrected in a timely manner. 
(Risk)
A13H0001 If safety issues are not reported formally through a company’s safety 
reporting system, there is a risk that hazards will not be managed 
effectively. (Risk)
None reported.
A13Q0098 If Transport Canada does not take into consideration the combined 
knowledge and experience of a new operator’s management team, 
there is a risk that the operator will lack the skills necessary to ensure 
the safety of flight operations. (Risk)
If process inspections carried out by Transport Canada do not 
examine factors related to a recent occurrence, there is a risk that 
those hazardous conditions will go undetected and will persist. (Risk)
None reported.
A13W0120 The operator’s safety management system was ineffective at 
identifying and correcting unsafe operating practices. (Cause and 
Contributing)
Transport Canada’s surveillance activities did not identify the 
operator's unsafe operating practices related to weight and balance 
and net take-off flight path calculations. Consequently, these unsafe 
practices persisted. (Cause and Contributing)
If Transport Canada does not adopt a balanced approach that 
combines inspections for compliance with audits of safety 
management processes, unsafe operating practices may not be 
identified, thereby increasing the risk of accidents. (Risk)
None reported.
A12Q0216 If Transport Canada’s oversight is dependent on the effectiveness of 
a company’s safety management system’s reporting of safety issues, 
there is a risk that important issues will be missed. (Risk)
None reported.
A12W0031 If adequate surveillance is not maintained by Transport Canada, there 
is an increased risk that operator safety deficiencies will not be 
identified. (Risk)
None reported.
A11O0031 During the transition to safety management systems, Transport 
Canada must recognize that operators may not always identify and 
mitigate hazards and adjust its oversight activities to be 
commensurate with the maturity of the operator’s safety 
management system. (Other)
None reported.
A10Q0117 The action taken by TC did not have the desired outcomes to ensure 
regulatory compliance; consequently, unsafe practices persisted. 
(Cause and Contributing)
None reported.
A10Q0098 The significant measures taken by TC did not have the expected 
results to ensure compliance with the regulations, and, consequently,
unsafe practices persisted. (Cause and Contributing)
Transport Canada 
has made 
significant changes 
to its surveillance 
program. These 
changes include 
updates to the 
methods used for 
surveillance 
planning and the 
introduction of 
tools that provide 
an improved 
capacity for the  

200 | TRANSPORTATION SAFETY BOARD OF CANADA
monitoring and 
analysis of risk 
indicators within 
the aviation system.
A07C0001 Transport Canada (TC) Prairie and Northern Region (PNR) 
management practices regarding the June 2006 replacement of the 
regional combined audit program, in order to manage safety 
management system (SMS) workload, did not conform to TC’s risk 
management decision-making policies. Reallocation of resources 
without assessment of risk could result in undetected regulatory non￾compliance. (Risk)
Although TC safety oversight processes identified the existence of 
supervisory deficiencies within TWA, the extent of the deficiencies 
was not fully appreciated by the PNR managers because of the 
limitations of the oversight system in place at that time. (Risk)
None reported. 

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Appendix I – West Wind threat and error management briefing reference 
card 
Source: West Wind Aviation L.P., ATR42 SOP (17 December 2016), p. 58. 

202 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix J – Similar occurrences in Canada involving contaminated critical 
surfaces during takeoff
Occurrence 
number Date Aircraft type Location Comments
N/A 1989-03-10 Fokker F-28 Dryden, ON Accident. Commercial operation. Contaminated 
critical surfaces before takeoff. Collision with 
terrain after takeoff. 24 fatalities. Moshansky 
Commission of Inquiry made many 
recommendations.
A98Q0057 1998-04-25 DHC-8-102 Québec, QC Incident. Commercial operation. Contamination 
before takeoff froze and resulted in jammed 
elevators during cruise. No injuries.
A98Q0194 1998-12-07 Britten￾Norman 
BN2A-26
Point-Lebel, 
QC
Accident. Commercial operation. Contaminated 
critical surfaces before takeoff. Loss of control 
and collision with terrain after takeoff. 6 fatalities, 
1 person missing, 3 serious injuries.
A99P0181 1999-12-28 Cessna 208 Abbotsford, BC Accident. Private operation. Contaminated critical 
surfaces before takeoff. Loss of control and 
collision with terrain after takeoff. 3 serious
injuries, 3 minor injuries.
A03O0088 2003-04-07 Found FBA￾2C1
Lake 
Temagami, ON
Accident. Private operation. Contamination 
before takeoff, loss of control and collision with 
terrain after takeoff. 2 fatalities.
A03O0302 2003-11-04 DHC-8-102 Ottawa, ON Incident. Commercial operation. Aircraft de-iced 
before takeoff. Control restrictions during 
takeoff, rejected takeoff. No injuries.
A04H0001 2004-01-17 Cessna 208B Pelee Island, 
ON
Accident. Commercial operation. Contaminated 
critical surfaces before takeoff, loss of control 
and collision with terrain after takeoff. 
10 fatalities.
A09C0017 2009-02-04 DHC-6 La Ronge, SK Accident. Commercial operation. Contaminated 
critical surfaces before takeoff. Loss of control 
and collision with terrain after takeoff. 7 minor 
injuries.
A12C0154 2012-11-18 Cessna 208B Snow Lake, MB Accident. Commercial operation. Contaminated 
critical surfaces before takeoff, loss of control 
and collision with terrain after takeoff. 1 fatality, 
7 serious injuries.
A13W0201 2013-12-17 Boeing 737-
300
Fort MacKay / 
Albian 
Aerodrome, AB
Incident. Commercial operation. Aircraft de-iced 
and anti-iced before departure. Insufficient 
quantity of Type IV fluid used for anti-icing. 
Difficulty controlling the aircraft after takeoff. No 
injuries. The TSB issued an aviation safety 
advisory to Transport Canada on 10 September 
2014.  

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Appendix K – Similar occurrences outside Canada involving contaminated 
critical surfaces during takeoff
Occurrence 
number Date Aircraft type Location Comments
DCA82AA011 1982-01-13 B737 Washington, 
D.C.
Contaminated critical surfaces. 78 
fatalities.
DCA88MA004 1987-11-15 DC-9-14 Denver, 
Colorado
Contaminated critical surfaces. 28 
fatalities.
A02F0002 2002-01-04 CL600-2B16 Birmingham, UK Frost contamination before 
takeoff. 5 fatalities.
A04F0207 2004-11-28 CL60 Montrose, 
Colorado
Contaminated critical surfaces 
before takeoff. 3 fatalities, 
3 seriously injured.
A04F0202 2004-11-21 CL600-2B19 Baotou, China Contaminated critical surfaces 
before takeoff. 53 fatalities.
A05F0023 2005-01-31 Cessna 208 Helsinki, Finland Contaminated critical surfaces 
before takeoff.
N/A 2007-01-25 Fokker 100 Pau, France Contaminated critical surfaces 
before takeoff.
A08F0020 2008-01-31 CL-600-2B19 Oslo, Norway Leading-edge contamination 
during takeoff run. No injuries.
A08F0026 2008-02-14 CL-600-2B19 Yerevan, 
Armenia
Contaminated critical surfaces 
before takeoff. 7 serious injuries.
N/A 2008-04-09 BAe Jetstream 41 Aberdeen, UK Contaminated critical surfaces 
before takeoff. Incident. No 
injuries.
A12F0033 2012-04-02 ATR72-201 Tyumen, Russia Contaminated critical surfaces 
before takeoff. 33 fatalities.
N/A 2013-03-04 Beechcraft 
Premier 1A
Annemasse, 
France
Contaminated critical surfaces 
before takeoff. 2 fatalities.
N/A 2016-03-04 ATR 72-212A Manchester, UK Contaminated critical surfaces 
before takeoff. Incident. No 
injuries. 

204 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix L – TSB pilot questionnaire
Q1. When I am at a remote airport, I have access to ground equipment that enables effective 
inspection of all of the aircraft’s critical surfaces for contamination.
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q2. When I am at a remote airport, I have access to ground equipment that enables 
adequate de‑icing of the aircraft’s critical surfaces before takeoff. 
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q3. When I am at a remote airport, I have access to ground equipment that enables 
adequate anti-icing of the aircraft’s critical surfaces before takeoff. 
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q4. When I am inbound to a remote airport where de-icing and anti-icing equipment is 
known to be inadequate and ground icing conditions exist or are forecast at that airport, I 
will divert to an alternate airport.
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q5. When I am inbound to a remote airport where de-icing and anti-icing equipment is 
known to be inadequate and icing conditions are encountered in flight and residual ice 
remains on the aircraft’s critical surfaces, I will divert to an alternate airport. 
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q6. I am able to have my aircraft de-iced effectively at remote airports. 
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q7. I am able to have my aircraft anti-iced effectively at remote airports. 
Never / Rarely / Sometimes / Usually / Always / Does not apply
Q8A. The operator I fly for has a ground icing operations program.
Yes / No
[If Yes to Q8A] Q8B. My company's ground icing program include directives on what to do if 
anti-icing and/or de-icing equipment and personnel are not available.
Yes / No
[If Yes to Q8A] Q8C. My company's ground icing program is effective?
Yes / No
[If Yes to Q8A] Q8D. Please describe how your company's ground icing program is effective 
or ineffective.
Q9. In the past year, I have received initial or recurrent training in aircraft surface 
contamination.
Yes / No 

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Q10. As a result of my initial or recurrent training, I understand the effects of aircraft critical 
surface contamination.
Strongly disagree / Disagree / Neither agree nor disagree / Agree / Strongly agree
Q12. In the past 5 years, I have seen pilots take off with contaminated critical surfaces.
Yes / No
[If Yes to Q12] Q12Y. Please give one or more examples. It would be useful if you could 
include some or all of the following information, but please do not include information that 
could identify individuals or operators.
• Aircraft type
• Circumstances 
• Degree of contamination 
• Availability and adequacy of de-icing and anti-icing equipment
• Your knowledge of any negative consequences
• Any other factors you know of that influenced pilot decision making during the 
events you witnessed.
Q13. Under which operations category do you typically fly?
• Private Operators (CARs subpart 604)
• Aerial work (CARs subpart 702)
• Air taxi (CARs subpart 703)
• Commuter (CARs subpart 704)
• Airline (CARs subpart 705)
• Other (please specify)
Q14. Please select from the dropdown list the primary aircraft type you currently fly:
• Piston single engine
• Piston multi engine ≤ 12 500 lbs
• Piston multi engine > 12 500 lbs
o CL-215
o DC-3
• Turboprop single engine
o PC-12
o C-208
• Turboprop multi engine ≤ 12 500 lbs
o Beech 90
o Beech 99
o Beech 100 

206 | TRANSPORTATION SAFETY BOARD OF CANADA
o Beech 200
o Beech 300
o DHC-6
o MU2
o SA226
• Turboprop multi engine > 12 500 lbs to 25 000 lbs
o Beech 1900
o SA-227
• Turboprop multi engine > 25 000 lbs
o ATR 42/72
o CL-415
o DHC-8
o HS-748
• Jet multi engine ≤ 70 000 lbs
• Jet multi engine > 70 000 lbs
Q15. What type of pilot licence do you currently hold?
• Airline transport pilot license (ATPL)
• Commercial pilot license (CPL)
• Foreign licence validation certificate (FLVC)
• Other (please specify)
Q16. What is your total flight time hours on all aircraft types?
Q17. What is your total pilot-in-command flight time hours?
Q18. How many years have you been employed as a pilot?
Q19. Of your total experience as a pilot, how many winter seasons did you conduct flights to 
remote airports?
Q20. How many years have you been employed by your current employer?
Q21. What is your primary role at the operator you fly for?
• Management pilot
• Check and/or training pilot
• Line pilot
Q22. What crew position do you hold on the aircraft type you currently fly most frequently?
• Captain
• First officer
• Other (please specify) 

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Q23. What is your total flight time hours on the aircraft type you currently fly most 
frequently?
Q24. What is your pilot-in-command flight time hours on the aircraft type you currently fly 
most frequently? 

208 | TRANSPORTATION SAFETY BOARD OF CANADA
Appendix M – Summary of TSB pilot questionnaire responses
Responses to questions 1 to 7 and 10 were on 5-point Likert scales. These were coded for 
analysis using a scale of 0 to 4, and the responses that indicated “does not apply” were 
assigned a null value.
Question 1: When I am at a remote airport, I have access to ground equipment that 
enables effective inspection of all of the aircraft’s critical surfaces for contamination.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
26 (4%) 177 (27%) 174 (27%) 178 (27%) 96 (15%) 4 (1%)
• Mean = 2.22
• Median = 2.00
• Mode = 3.00
• Standard deviation = 1.12
• Variance = 1.25
Almost one-third (31%) of respondents indicated that they never or rarely have access to 
ground equipment that enables effective inspection of the aircraft’s critical surfaces. A 
further 27% replied they sometimes had access to the equipment. Less than half (42%) 
indicated they usually or always have access to such equipment.
Question 2: When I am at a remote airport, I have access to ground equipment that 
enables adequate de‑icing of the aircraft’s critical surfaces before takeoff.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
41 (6%) 191 (29%) 177 (27%) 165 (25%) 77 (12%) 4 (1%) 

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• Mean = 2.07
• Median = 2.00
• Mode = 1.00
• Standard deviation = 1.13
• Variance = 1.27
More than one-third (35%) of respondents indicated that they never or rarely have access 
to ground equipment than enables adequate de-icing of their aircraft at remote airports. A 
further 27% stated they sometimes had access to the equipment. Only 37% indicated they 
usually or always have access to necessary equipment.
Question 3: When I am at a remote airport, I have access to ground equipment that 
enables adequate anti-icing of the aircraft’s critical surfaces before takeoff.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. 
Always
Does not 
apply
207 (32%) 206 (31%) 98 (15%) 83 (13%) 45 (7%) 16 (2%)
• Mean = 1.30
• Median = 1.00
• Mode = 0.00
• Standard deviation = 1.24
• Variance = 1.54 

210 | TRANSPORTATION SAFETY BOARD OF CANADA
Almost two-thirds of respondents (63%) reported they never or rarely have access to 
equipment for anti-icing their aircraft at remote airports, and a further 15% indicated they 
sometimes have access to this equipment. Only 20% of respondents said they usually or 
always had adequate anti-icing equipment available.
Question 4: When I am inbound to a remote airport where de-icing and anti-icing 
equipment is known to be inadequate and ground icing conditions exist or are 
forecast at that airport, I will divert to an alternate airport.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
49 (7%) 120 (18%) 120 (18%) 159 (24%) 187 (29%) 20 (3%)
• Mean = 2.50
• Median = 3.00
• Mode = 4.00
• Standard deviation = 1.30
• Variance = 1.68 

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When presented a statement about diverting from an airport with inadequate equipment 
and ground icing conditions, 25% of respondents replied they would never or rarely divert 
to an alternate airport, and 18% said they would sometimes divert. Most (53%) indicated 
they would usually or always divert in this situation.
Question 5. When I am inbound to a remote airport where de-icing and anti-icing 
equipment is known to be inadequate, icing conditions are encountered in flight, and 
residual ice remains on the aircraft’s critical surfaces, I will divert to an alternate 
airport.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
86 (13%) 172 (26%) 120 (18%) 116 (18%) 137 (21%) 24 (4%)
• Mean = 2.07
• Median = 2.00
• Mode = 1.00
• Standard deviation = 1.37
• Variance = 1.87
Responses to a similar statement about locations where ground equipment is known to be 
inadequate, coupled with in-flight icing and contaminated surfaces, followed the pattern 
seen in responses to Question 4, although slightly fewer respondents stated that they would 
divert:
• 39% of respondents indicated they would never or rarely divert in this situation;
• a further 18% said they would sometimes divert; and
• 39% said they would usually or always divert. 

212 | TRANSPORTATION SAFETY BOARD OF CANADA
Question 6. I am able to have my aircraft de-iced effectively at remote airports.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
37 (6%) 216 (33%) 152 (23%) 180 (27%) 65 (10%) 5 (1%)
• Mean = 2.03
• Median = 2.00
• Mode = 1.00
• Standard deviation = 1.11
• Variance = 1.24
The responses suggest that de-icing at remote airports can be challenging:
• 39% of respondents indicated that they are never or rarely able to have their 
aircraft de-iced;
• another 23% responded they are sometimes able to do so; and
• 37% said they are usually or always able to have their aircraft de-iced at remote 
airports.
Question 7. I am able to have my aircraft anti-iced effectively at remote airports.
0. Never 1. Rarely 2. Sometimes 3. Usually 4. Always Does not 
apply
231 (35%) 213 (33%) 89 (14%) 68 (10%) 29 (4%) 25 (4%)
• Mean = 1.13
• Median = 1.00 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 213
• Mode = 0.00
• Standard deviation = 1.16
• Variance = 1.34
The responses indicate that anti-icing capability at remote airports is less available than 
de-icing. More than two-thirds of respondents (68%) said they were never or rarely able to 
have their aircraft anti-iced effectively, and a further 14% reported they could sometimes
do so. Only 14% of respondents said they were usually or always able to anti-ice at remote 
airports.
Question 8A. The operator I fly for has a ground icing operations program.
0. No 1. Yes n =
56 (9%) 599 (91%) 655 (100%)
• Mean = 0.91
• Median = 1.00
• Mode = 1.00
• Standard deviation = 0.28
• Variance = 0.08 

214 | TRANSPORTATION SAFETY BOARD OF CANADA
Most respondents (91%), indicated their operator has a ground icing operations program in 
place.
Question 8B. My company's ground icing program includes directives on what to do if 
anti-icing and/or de-icing equipment and personnel are not available.
0. No 1. Yes n =
188 (32%) 406 (68%) 594 (100%)
• Mean = 0.68
• Median = 1.00
• Mode = 1.00
• Standard deviation = 0.47
• Variance = 0.22
More than two-thirds (68%) of responses to this question indicated the respondents’ 
company’s ground icing program included directives on what to do if anti-icing or de-icing  

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 215
facilities or services are not available. About one-third (32%) reported their company’s 
program did not provide such directives.
Question 8C. My company's ground icing program is effective.
0. No 1. Yes n =
196 (33%) 396 (67%) 592 (100%)
• Mean = 0.67
• Median = 1.00
• Mode = 1.00
• Standard deviation = 0.47
• Variance = 0.22
About two-thirds (67%) of respondents answering this question indicated that their 
company’s ground icing program is effective, while the remaining one-third (33%) 
disagreed and indicated their company’s program was not effective.
Question 8D. Please describe how your company's ground icing program is effective 
or ineffective.
The individualized responses for this item were reviewed in the context of the investigation;
however, the responses are not included here, due to the required protection of certain 
information.
Question 9. In the past year, I have received initial or recurrent training in aircraft 
surface contamination. 

216 | TRANSPORTATION SAFETY BOARD OF CANADA
0. No 1. Yes n =
9 (1%) 646 (99%) 655 (100%)
• Mean = 0.99
• Median = 1.00
• Mode = 1.00
• Standard deviation = 0.12
• Variance = 0.01
Almost all respondents (99%) reported that they had received training in aircraft surface 
contamination in the past year.
Question 10. As a result of my initial or recurrent training, I understand the effects of 
aircraft critical-surface contamination.
0. Strongly 
disagree
1. Disagree 2. Neither 
agree nor 
disagree
3. Agree 4. Strongly 
agree
n =
16 (2%) 5 (1%) 14 (2%) 216 (33%) 395 (61%) 646 (100%)
• Mean = 3.50
• Median = 4.00
• Mode = 4.00
• Standard deviation = 0.80
• Variance = 0.64 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 217
Most respondents (94%) strongly agreed or agreed that they understand the effects of 
aircraft critical-surface contamination as a result of their training, while 2% said they 
neither agreed nor disagreed. A small group of respondents (3%) responded that they 
strongly disagreed or disagreed with this statement.
Question 11. In the past 5 years, I have seen pilots take off with contaminated critical 
surfaces.
0. No 1. Yes n =
171 (26%) 484 (74%) 655 (100%)
About three-quarters of respondents (74%) indicated that they had witnessed pilots take
off with contaminated critical surfaces in the past 5 years. Only 25% of respondents 
reported they had not.
Question 12Y. [This question was presented only to respondents who answered yes 
to Question 12, and offered an unlimited text field for response.] Please give one or 
more examples. It would be useful if you could include some or all of the following  

218 | TRANSPORTATION SAFETY BOARD OF CANADA
information, but please do not include information that could identify individuals or 
operators.
• Aircraft type
• Circumstances 
• Degree of contamination 
• Availability and adequacy of de-icing and anti-icing equipment
• Your knowledge of any negative consequences
• Any other factors you know of that influenced pilot decision making during 
the events you witnessed.
Of the 484 respondents who answered “yes” to Question 12 above, 396 provided further 
information about the events they had seen.
About three-quarters (73%) of these 396 respondents made no mention of negative 
consequences associated with events they had seen, 24% reported they had not seen any 
adverse consequences, and only a small number (4%, or 14 of 396 responses with details) 
reported they knew of negative consequences such as reduced climb performance or 
difficulty in controlling the aircraft. 
The following table summarizes responses to Question 12Y.
Number of 
responses
Question 12 Y all responses
Completed the survey 655 (100%)
Witnessed an aircraft take off in the past 
five years with contaminated critical 
surfaces
484
Provided details 396
Aircraft type 
(Many responses that provided 
details reported multiple 
aircraft types, consequently 
sum of responses is > 282 and 
sum of proportions is > 100%) 
Responses that identified one or more aircraft types 
or operation types
282 [100%]
Reponses that identified aircraft types 
common in air taxi operations
169 [60%]
Reponses that identified aircraft types 
common in commuter operations
120 [43%]
Responses that identified aircraft types 
common in airliner operations
146 [52%]
Adverse consequences
Observed adverse consequences of contaminated 
surfaces.
14 (4%)
Did not observe any adverse consequences 96 (24%)
No mention of adverse consequences 288 (73%)
Equipment
Mentioned equipment not available, or 
inaccessible.
84 (21%) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 219
This includes a total lack of equipment, or else a 
statement that existing equipment is locked away, 
frozen into snowbanks, or similarly unavailable.
Mentioned equipment available and accessible, 
but insufficient for task, or unserviceable.
147 (37%)
Mentioned equipment available, but not used.
(Often correlated with the idea that equipment was 
insufficient for the task.)
142 (36%)
[100%]
Equipment not used due to time pressure 33 [23%]
Equipment not used due to financial cost 32 [23%]
Equipment not used for fear of causing 
or worsening contamination
20 [14%]
Equipment not used/not available due to 
competition between operators 
preventing access to existing equipment at 
remote airports
11 [8%]
Question 13. Under which operations category do you typically fly?
CARs 702 
Aerial work
CARs 703 
Air taxi
CARs 704 
Commuter
CARs 705 
Airline
CARs 604 
Private 
operator
Other
6 (1%) 207 (32%) 96 (15%) 304 (46%) 22 (3%) 20 (3%)
The majority (46%) of respondents indicated they fly in the airline category (CARs 705), 
almost one-third (32%) indicated air taxi as their primary operational category (CARs 703), 
and about 15% said they fly in the commuter category (CARs 704). Only 1% of respondents 
indicated their operations category was aerial work (CARs 702). 
A small number of respondents (3%) fly under a private operator certificate (CARs 604). 
About the same number opted not to pick a single category, but instead wrote in a 
combination of categories; almost all such responses included air taxi (CARs 703) and 
commuter (CARs 704) categories, and about half included the airline category (CARs 705).
Question 14. Please select from the dropdown list the primary aircraft type you 
currently fly.
Piston 
single￾engine 
(1)
Piston 
multi￾engine 
≤ 12 500
lb (2)
Piston 
multi￾engine 
> 12 500
lb (3)
Turboprop 
single￾engine (4)
Turboprop 
multi￾engine 
≤ 12 500 lb 
(5)
Turboprop 
multi￾engine 
> 12 500 lb 
to 25 000
lb (6)
Turboprop 
multi￾engine 
> 25 000 lb 
(7)
Jet 
multi￾engine 
≤ 70 0
00 lb 
(8)
Jet 
multi￾engine 
> 70 000
lb (9) 

220 | TRANSPORTATION SAFETY BOARD OF CANADA
5 (1%) 8 (1%) 8 (1%) 60 (9%) 177 (27%) 62 (9%) 216 (33%) 20 
(3%)
99 (15%)
Respondents reported flying a diverse spectrum of aircraft types. 
A relatively small number of respondents (3%) fly piston-engine aircraft: 
• 1% fly piston-powered single-engine aircraft;
• 1% fly multi-engine aircraft of 12 500 pounds (lb) or less; and 
• 1% fly heavy multi-engine aircraft of over 12 500 lb. 
Most respondents (79%) fly turboprop aircraft:
• 9% fly single-engine turboprop aircraft;
• 27% fly multi-engine turboprop aircraft of 12 500 lb or less;
• 9% fly multi-engine turboprop aircraft of 12 501 to 25 000 lb; and 
• 33% fly multi-engine turboprop aircraft of over 25 000 lb.
The remaining 18% of respondents fly multi-engine jet aircraft:
• 3% fly jets of 70 000 lb or less; and
• 15% fly jets of more than 70 000 lb.
Question 15. What type of pilot licence do you currently hold?
1. ATPL 2. CPL 3. Other n =
493 (75%) 159 (24%) 3 (0%) 655 (100%)
Three-quarters of respondents (75%) hold an airline transport pilot licence (ATPL). Most of 
the remainder (24%) hold a commercial pilot licence (CPL), while three respondents (< 1%) 
hold other licenses. 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 221
Question 16. What is your total flight time hours on all aircraft types?
Number of responses that fall in the described categories
0 - 1500 
hours
1501 – 5000
hours
5001 – 10 000 
hours
10 001 + 
hours
101 (15%) 239 (36%) 158 (24%) 155 (24%)
Question 17. What is your total pilot-in-command flight time hours?
Number of responses that fall in the described categories
0 - 1500 
hours
1501 – 5000
hours
5001 – 10 000 
hours
10 001 + 
hours
240 (37%) 211 (32%) 117 (18%) 85 (13%)
Question 18. How many years have you been employed as a pilot?
One-quarter of respondents had been employed 5 years or less, half of the respondents had 
been employed between 5 and 20 years, and one-quarter had been employed 20 years or 
more.
• 652 respondents collectively reported 8819 years of employment.
o Of those, 492 pilots having an ATPL accounted for 8151 years of employment,
and
o 157 pilots having a CPL accounted for 623 years of employment.
• 3 respondents with licences other than ATPL and CPL reported a total of 45 years of 
employment.
• Mean = 13.53
• Median = 10.50
• Mode = 5.00
• Standard deviation = 10.74
• Variance = 115.39
• Range = 54.00
• Interquartile range = 15.00 

222 | TRANSPORTATION SAFETY BOARD OF CANADA
Question 19. Of your total experience as a pilot, how many winter seasons did you 
conduct flights to remote airports?
One-quarter of respondents had experienced 3 or fewer winter seasons, half of the 
respondents had experienced between 3 and 13 winter seasons, and one-quarter had 
experienced 13 or more winter seasons.
• 655 respondents collectively reported 5997 winter seasons during which they 
conducted flights to remote airports.
o Of those, 493 pilots having an ATPL accounted for 5540 winter seasons of 
experience, and
o 159 pilots having a CPL accounted for 432 winter seasons of experience. 
• 3 respondents with licences other than ATPL and CPL reported an additional 
25 winter seasons of experience.
• Mean = 9.15
• Median = 6.00
• Mode = 1.00
• Standard deviation = 8.73
• Variance = 76.17
• Range = 54.00
• Interquartile range = 10.00 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 223
Question 20. How many years have you been employed by your current employer?
One-quarter of respondents had spent 1.5 years or less with their current employer, half of 
respondents had spent between 1.5 and 10 years, and one-quarter had spent 10 years or 
more with their current employer.
• 655 respondents collectively reported having 4419 years employment with their 
current employer.
o Of those, 493 pilots having an ATPL accounted for 4036 years employment with 
their current employers, and
o 159 pilots having a CPL accounted for 379 years with their current employers.
• 3 respondents with licences other than ATPL and CPL reported an additional 4 years 
with their current employers.
• Mean = 6.76
• Median = 4.00
• Mode = 1.00
• Standard deviation = 7.29
• Variance = 53.16
• Range = 53.00
• Interquartile range = 8.50 

224 | TRANSPORTATION SAFETY BOARD OF CANADA
Question 21. What is your primary role at the operator you fly for?
1. Line pilot 2. Check/training pilot 3. Management 
pilot
n =
524 (80%) 91 (14%) 40 (6%) 655 (100%)
Most respondents (80%) are line pilots with their organization, 14% said they are check or 
training pilots, and 6% are management pilots.
Question 22. What crew position do you hold on the aircraft type you currently fly 
most frequently?
1. Captain 2. First officer 3. Other n =
437 (67%) 214 (33%) 4 (1%) 655 (100%)
Two-thirds of respondents indicated they hold a captain position on the aircraft type they 
fly most frequently, and 33% stated they fly as a first officer.
Q23. What is your total flight time hours on the aircraft type you currently fly most 
frequently?
Number of responses that fall in the described categories
0 - 1000 
hours
1001 – 2500
hours
2501 – 7500 
hours
7500 + 
hours
287 (44%) 164 (25%) 152 (23%) 50 (8%) 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 225
Q24. What is your pilot-in-command flight time hours on the aircraft type you 
currently fly most frequently?
Number of responses that fall in the described categories
0
hours
1 - 1000 
hours
1001 – 2500
hours
2501 – 7500 
hours
7500 + 
hours
196 (30%) 226 (35%) 95 (15%) 111 (17%) 25 (4%) 

226 | TRANSPORTATION SAFETY BOARD OF CANADA
GLOSSARY
AFM Airplane Flight Manual
AGL above ground level
AOA angle of attack
APM aircraft performance monitoring
ASL above sea level
ATC air traffic control
ATF aerodrome traffic frequency
ATPL airline transport pilot licence
ATR Avions de Transport Régional
AWOS automated weather observation system
CA convening authority
CAD Civil Aviation Directive
CAP corrective action plan
CARs Canadian Aviation Regulations
CASS Commercial Air Services Standards
CBR California bearing ratio 
CMM Component Maintenance Manual
COM Company Operations Manual
CRM crew resource management
CVR cockpit voice recorder
CYNL Points North Landing Airport
CYPA Prince Albert (Glass Field) Airport
CYSF Stony Rapids Airport
CYXE Saskatoon/John G. Diefenbaker International Airport
CZFD Fond-du-Lac Airport
CZWL Wollaston Lake Airport
DFO Director of Flight Operations
DZ drizzle
EGPWS enhanced ground proximity warning system
EM enhanced monitoring
FA flight attendant
FAA Federal Aviation Administration
FAR 25 FAA, Code of Federal Regulations, Title 14: Aeronautics and Space, Part 25: 
Airworthiness Standards: Transport Category Airplanes
FCOM Flight Crew Operating Manual
FDM flight data monitoring
FDR flight data recorder
FL flight level
FMS flight management system
FO first officer 

AIR TRANSPORTATION SAFETY INVESTIGATION REPORT A17C0146 | 227
FOQA flight operational quality assurance
FZBR freezing mist
FZDZ freezing drizzle
FZRA freezing rain 
FZFG freezing fog
FZUP freezing – unknown precipitation 
GFA graphic area forecast
GIOP ground icing operations program
ICAO International Civil Aviation Organization
inHg inches of mercury
IPB internal process bulletin
KIAS knots indicated airspeed
L1 front emergency exit (left)
L2 rear entry door (left)
LOSA line operations safety audit
MANOBS Manual of Surface Weather Observation Standards
METAR aerodrome routine meteorological report
NASIMS National Aviation Safety Information Management System
NCAMX National Civil Aviation Management Executive Committee
NM nautical mile
NOO National Oversight Office
NOS Notice of Suspension
OAB Oversight Advisory Board
OFP operational flight plan
ORM operational risk management
PF pilot flying
PI process inspection
PIC pilot-in-command
PNF pilot not flying
PVI program validation inspection
R1 front emergency exit (right)
R2 rear service door (right)
RA rain
RCMP Royal Canadian Mounted Police
RIN risk-indicator number 

228 | TRANSPORTATION SAFETY BOARD OF CANADA
SI staff instruction
SM statute mile
SMS safety management system
SOP standard operating procedure
T true
TAF aerodrome forecast
TC Transport Canada
TCCA Transport Canada Civil Aviation
TEM threat and error management 