National Transportation Safety Board
Aviation Accident Final Report
Location:

Berthoud, CO

Accident Number:

CEN17FA111

Date & Time:

02/27/2017, 0741 MST

Registration:

N2461N

Aircraft:

CESSNA 172S

Aircraft Damage:

Substantial

Defining Event:

Aerodynamic stall/spin

Injuries:

2 Fatal

Flight Conducted Under:

Part 91: General Aviation - Instructional

Analysis
The flight instructor and the commercial pilot receiving instruction were conducting a local
training flight to practice aerodynamic spins. A review of air traffic control radar track data
established that the airplane entered two aerodynamic spins during the flight. The first
aerodynamic spin began at 10,300 ft mean sea level (msl), and the airplane descended about
1,000 ft before it recovered into a climb. The airplane then made a series of climbing turns
until reaching 10,800 ft msl where it entered a second aerodynamic spin. The airplane did not
recover from the second spin before it descended below available radar coverage at 6,800 ft
msl (about 1,700 ft above the ground). Multiple witnesses reported seeing the airplane
descending in a nose-down spin. One witness stated that the airplane completed about 5 turns
in the spin before it descended behind a tree line into a reservoir.
The airplane's Pilot Operating Handbook specified that at least 1,000 ft of altitude loss should
be expected for a one-turn spin and recovery and that a six-turn spin and recovery may require
more than twice that altitude loss because the airplane can develop a rapid rate of rotation and
a steep nose-down pitch attitude. A postaccident examination revealed no evidence of a
mechanical malfunction or failure that would have precluded normal operation during the
flight. Additionally, the examination did not identify any foreign object debris that would have
limited full movement of the flight controls during the flight, and the airplane's weight and
balance were within the specified limits to conduct aerodynamic spins. It is likely that the
pilots did not apply prompt and/or correct flight control inputs to adequately recover from the
intentional aerodynamic spin.

Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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 The failure of the pilots to apply prompt and/or correct flight control inputs to adequately
recover from the intentional aerodynamic spin.

Findings
Aircraft

Flight control system - Incorrect use/operation (Cause)

Personnel issues

Aircraft control - Pilot (Cause)
Aircraft control - Instructor/check pilot (Cause)

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CEN17FA111

 Factual Information
History of Flight
Maneuvering

Aerodynamic stall/spin (Defining event)
Collision with terr/obj (non-CFIT)

On February 27, 2017, about 0741 mountain standard time, a Cessna 172S airplane, N2461N,
collided with a reservoir while maneuvering near Berthoud, Colorado. The flight instructor and
the pilot receiving instruction were fatally injured, and the airplane was substantially damaged.
The airplane was owned by McAir Aviation, LLC, and was operated by the company under the
provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Day visual meteorological
conditions prevailed for the local instructional flight that departed Rocky Mountain
Metropolitan Airport (BJC), Broomfield, Colorado, at 0724.
According to the operator, the purpose of the flight was for the pilot receiving instruction to
demonstrate his ability to enter and recover from aerodynamic spins as part of his required
training toward a flight instructor certificate.
According to a review of air traffic control radar track data, the first radar contact with the
airplane was at 0724:01 shortly after it departed runway 30R at BJC. After takeoff, the airplane
proceeded north toward Longmont, Colorado. At 0734:30, the airplane crossed over Colorado
Highway 66 at 10,000 ft mean sea level (msl). At 0736:12, the airplane was about 1 mile east of
the Highland Reservoir No. 2 at 10,300 ft msl. According to calculations based on radar data,
the airplane turned to a westerly course as the ground speed decreased below 40 knots.
Between 0736:53 and 0737:07, the airplane descended from 10,300 ft msl to 9,300 ft msl, and
the calculated average descent rate was about 4,300 ft per minute during the 14 second
descent. Following the rapid descent, the airplane entered a climb to 10,800 ft msl and
completed a turn from an east course to a west course. At 0740:35, about 1 mile south of the
Culver Reservoir (also known as Blue Mountain Reservoir), the airplane completed a 90° right
turn, and the ground speed decreased below 40 knots. Between 0741:03 and 0741:40, the
airplane descended from 10,800 ft msl to 6,800 ft msl, and the calculated average descent rate
was about 6,500 ft per minute. The last radar data point was at 0741:40 at 6,800 ft msl when
the airplane descended below available radar coverage (about 1,700 ft above the ground).
A witness reported that she was outside feeding her horses when she observed the airplane
flying overhead. She reported hearing a reduction in engine power before seeing the airplane
pitch nose-down and enter a spin toward the ground. She stated that the airplane completed
about 5 turns in the spin before it descended below a tree line located between her position and
Culver Reservoir. She reported that the airplane rotated slowly throughout the spin maneuver
and that she did not hear the engine regain power. The witness also indicated that it was very
common for airplanes to complete similar maneuvers in the airspace near her property.
Another witness reported that he initially heard the airplane overfly his residence. He stated
that he heard a reduction in engine power and then saw the airplane through a window

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CEN17FA111

 descending nose-down in a spin. The witness reported that the airplane was rotating slowly
during the spin maneuver. He also noted that he did not observe any smoke or flames coming
from the airplane. The airplane descended below a tree line located between his residence and
Culver Reservoir. Although the witness did not see the airplane impact the reservoir, he
reported hearing a sound consistent with a ground impact.

Pilot Information
Certificate:

Commercial

Age:

23, Male

Airplane Rating(s):

Single-engine Land

Seat Occupied:

Right

Other Aircraft Rating(s):

None

Restraint Used:

3-point

Instrument Rating(s):

Airplane

Second Pilot Present:

Yes

Instructor Rating(s):

None

Toxicology Performed:

Yes

Medical Certification:

Class 3 Without
Waivers/Limitations

Last FAA Medical Exam:

01/06/2015

Occupational Pilot:

No

Last Flight Review or Equivalent:

08/31/2016

Flight Time:

(Estimated) 550 hours (Total, all aircraft)

Flight Instructor Information
Certificate:

Flight Instructor; Commercial

Age:

58, Male

Airplane Rating(s):

Single-engine Land

Seat Occupied:

Left

Other Aircraft Rating(s):

None

Restraint Used:

3-point

Instrument Rating(s):

Airplane

Second Pilot Present:

Yes

Instructor Rating(s):

Airplane Single-engine; Instrument
Airplane

Toxicology Performed:

Yes

Medical Certification:

Class 2 With Waivers/Limitations

Last FAA Medical Exam:

06/24/2016

Occupational Pilot:

Yes

Last Flight Review or Equivalent:

06/30/2016

Flight Time:

(Estimated) 6678.5 hours (Total, all aircraft)

According to Federal Aviation Administration (FAA) records, the 58-year-old flight instructor
held a commercial pilot certificate with ratings for airplane single-engine land and instrument
airplane. He also held a flight instructor certificate with ratings for airplane single-engine land
and instrument airplane. His last aviation medical examination was on June 24, 2016, when he
was issued a second-class medical certificate with a limitation to have glasses available for near
vision. A search of FAA records showed no previous accidents, incidents, or enforcement
proceedings. He was employed by McAir Aviation as the chief pilot in charge of flight
instruction. On June 30, 2016, the FAA renewed his chief pilot authorization following an oral
examination and checkride in a Cessna 172S. The operator reported that the flight instructor
had a total flight experience of 6,678.5 hours.

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CEN17FA111

 According to FAA records, the 23-year-old pilot receiving instruction held a commercial pilot
certificate with ratings for airplane single-engine land and instrument airplane. The
commercial pilot certificate was issued on August 31, 2016. His last aviation medical
examination was on January 6, 2015, when he was issued a third-class medical certificate with
no limitations or restrictions. A search of FAA records showed no previous accidents, incidents,
or enforcement proceedings. A pilot logbook was not recovered during the investigation;
however, according to his father, the pilot receiving instruction had about 550 hours total flight
experience of which about 400 hours had been flown during the previous year.

Aircraft and Owner/Operator Information
Aircraft Make:

CESSNA

Registration:

N2461N

Model/Series:

172S

Aircraft Category:

Airplane

Year of Manufacture:

2005

Amateur Built:

No

Airworthiness Certificate:

Normal; Utility

Serial Number:

172S10043

Landing Gear Type:

Tricycle

Seats:

2

Date/Type of Last Inspection:

01/12/2017, 100 Hour

Certified Max Gross Wt.:

2550 lbs

Time Since Last Inspection:

52 Hours

Engines:

1 Reciprocating

Airframe Total Time:

4703 Hours at time of
accident

Engine Manufacturer:

Lycoming

ELT:

C91A installed, activated,
did not aid in locating
accident

Engine Model/Series:

IO-360-L2A

Registered Owner:

McAir Aviation, LLC

Rated Power:

180 hp

Operator:

McAir Aviation, LLC

Operating Certificate(s)
Held:

Pilot School (141)

The 2005-model-year airplane, serial number 172S10043, was a high-wing monoplane of
aluminum semi-monocoque construction. The airplane was powered by a 180-horsepower, 4cylinder, Lycoming IO-360-L2A reciprocating engine, serial number L-31665-51A. The engine
provided thrust through a fixed-pitch, two-blade, McCauley model 1A170E/JHA7660
propeller, serial number ZF23025. The airplane was equipped with a fixed tricycle landing gear
and wing flaps and had a certified maximum gross weight of 2,550 pounds. The FAA issued the
airplane a standard airworthiness certificate on November 29, 2005.
According to dispatch documentation, the airplane's hour meter indicated 6,053.7 hours before
the flight. The airplane's hour meter indicated 6,054.2 hours at the accident site. At the time of
the accident, the airframe had accumulated a total service time of 4,703 hours. The engine had
accumulated a total service time of 5,994.6 hours since new and 1,862 hours since its most
recent overhaul on December 21, 2012. The propeller had accumulated a total service time of

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CEN17FA111

 4,703 hours and 1,862 hours since its most recent overhaul on January 4, 2013. The last annual
inspection of the airplane was completed on October 25, 2016, at 4,552.1 total airframe hours.
A 100-hour inspection was completed on January 12, 2017, at 4,651.2 total airframe hours. The
rudder return springs were replaced on January 24, 2017, at 4,668.8 total airframe hours. The
rear bench seat and rear seat restraints were removed on February 13, 2017. A postaccident
review of the maintenance records found no history of unresolved airworthiness issues.
The airplane had two fuel tanks, one located in each wing, and a total fuel capacity of 56 gallons
(53 gallons usable). According to dispatch records, the airplane departed with 27 gallons of
fuel.
The dispatch records included a weight-and-balance calculation worksheet for the flight.
According to the worksheet, the combined weight of the flight instructor and the pilot receiving
instruction was 325 pounds; the airplane departure weight was 2,173.5 pounds; and the
calculated moment arm was 40.3 inches aft-of-datum. The postmortem weights of the flight
instructor and the pilot-receiving-instruction were 204 pounds and 150 pounds, respectively. A
postaccident weight-and-balance calculation, using the postmortem weights and a fuel
consumption rate of 11 gallons per hour, established that the airplane was operating within the
constraints of the utility category at the time of the accident.

Meteorological Information and Flight Plan
Conditions at Accident Site:

Visual Conditions

Condition of Light:

Day

Observation Facility, Elevation:

FNL, 5016 ft msl

Distance from Accident Site:

15 Nautical Miles

Observation Time:

0756 MST

Direction from Accident Site:

30°

Lowest Cloud Condition:

Clear

Visibility

10 Miles

Lowest Ceiling:

None

Visibility (RVR):

Wind Speed/Gusts:

5 knots /

Turbulence Type
Forecast/Actual:

Clear Air / Clear Air

Wind Direction:

50°

Turbulence Severity
Forecast/Actual:

Moderate / Moderate

Altimeter Setting:

29.68 inches Hg

Temperature/Dew Point:

-7°C / -9°C

Precipitation and Obscuration:

No Obscuration; No Precipitation

Departure Point:

Bloomfield, CO (BJC)

Type of Flight Plan Filed:

None

Destination:

Bloomfield, CO (BJC)

Type of Clearance:

None

Departure Time:

0724 MST

Type of Airspace:

Class E

A postaccident review of available meteorological data established that day visual
meteorological conditions prevailed at the accident site. The nearest aviation weather reporting
station was located at Fort Collins-Loveland Municipal Airport (FNL) about 15 miles northnortheast of the accident site. At 0756, about 15 minutes after the accident, the FNL automated

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CEN17FA111

 surface observing system reported wind 050° at 5 knots, 10 miles surface visibility, a clear sky,
temperature -7°C, dew point -9°C, and an altimeter setting 29.68 inches of mercury.

Wreckage and Impact Information
Crew Injuries:

2 Fatal

Aircraft Damage:

Substantial

Passenger Injuries:

N/A

Aircraft Fire:

None

Ground Injuries:

N/A

Aircraft Explosion:

None

Total Injuries:

2 Fatal

Latitude, Longitude:

40.267222, -105.154167

The airplane wreckage was found partially submerged in Culver Reservoir at an altitude of
5,142 ft msl. Airbags were used to float the airplane to the shore where it was subsequently
recovered by a crane. All major structural components and flight controls remained intact. The
aileron and flap control cables were disconnected at the wing root turnbuckles by the salvage
company before the wings were removed for transport. The elevator and rudder cable circuits
were not disconnected during wreckage recovery.
The leading edge of the right wing was crushed upward and aft to the front spar about 45°. The
leading edge of the left wing was crushed flat. The aft fuselage and tail cone were compressed
on the right side and buckled slightly outward on the left side. The engine was compressed up
and aft into the firewall. Aileron control cable continuity was established from the left and right
aileron bell cranks to the center wing area where they had been disconnected to facilitate
recovery of the wreckage. The aileron autopilot roll servo cables remained on the capstan and
attached to the bell crank. The aileron cables remained installed on the left and right control
column sprockets and were wrapped around the interconnect pulley. A measurement of the
wing flap actuator was consistent with the flaps being fully retracted at impact.
Elevator control cable continuity was established from the forward elevator bell crank to the aft
elevator bell crank. The forward elevator bell crank was bent due to floor compression damage
that was sustained during impact. The elevator autopilot pitch servo cables were on the
capstan, and the bridal cables remained attached to the control cable. Rudder control cable
continuity was established from the rudder torque tubes to the rudder horn. The rudder stops
exhibited normal wear signatures. The rudder return springs remained attached to the rudder
assemblies, and no anomalies were observed with their installation. The rudder torque tube
bearing block covers exhibited fracture features consistent with impact-related damage. The
parking brake cable on the left side left brake pedal was fractured. The pilot side left brake
master cylinder connection rod was fractured near the brake pedal attachment.
The examination did not identify any foreign object debris within the cabin, cockpit, wings, or
the aft fuselage that would have limited full movement of the flight controls during the flight.
Both structural seat pans exhibited downward deformation. A headset bag was located under
each of the cockpit seats, and the headset bags were trapped by the deformed seat pans. A fuel

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CEN17FA111

 sample that was obtained from the fuel strainer assembly tested negative for water
contamination using water-detection paste. The postaccident airframe examination revealed
no evidence of a mechanical malfunction or failure that would have precluded normal
operation during the flight.
The engine had partially separated from the firewall. The top spark plugs, valve covers, and all
rear accessories were removed to facilitate the examination. Mechanical continuity was
confirmed from the engine components to their respective cockpit controls, with exception of
the mixture control rod end that had separated at the shaft but remained connected to the
mixture control arm. The fracture of the mixture control rod end exhibited features consistent
with an overstress failure. Internal engine and valve train continuity were established as the
crankshaft was rotated. Compression and suction were observed on all cylinders in conjunction
with crankshaft rotation. The top spark plugs exhibited features consistent with normal engine
operation. A borescope inspection revealed no anomalies with the cylinders, valves, pistons, or
lower spark plugs.
There were no obstructions observed between the air filter housing and the fuel servo. The
exhaust was crushed upward and aft. The intake tubes for cylinders nos. 1 and 2 were found
displaced aft from impact damage. The residual water was cleaned out of both magnetos with
contact cleaner and compressed air. A spark was produced on all posts when each magneto was
rotated by hand. The fuel flow divider, flow transducer, and fuel hoses were clear of
contaminates. No anomalies were noted with the mechanical fuel pump when it was operated
by hand. The fuel flow divider contained fuel. The oil pickup screen was free of contamination.
The propeller remained attached to the crankshaft flange. One blade was found relatively
straight, and the other blade was bent slightly aft. Neither propeller blade exhibited chordwise
scoring, rubbing, or burnishing. The postaccident examination revealed no evidence of a
mechanical malfunction or failure that would have precluded normal engine operation during
the flight.

Medical And Pathological Information
The Larimer County Medical Examiner's Office, Loveland, Colorado, performed autopsies on
the flight instructor and the pilot receiving instruction. The cause of death for both individuals
was attributed to multiple blunt-force injuries sustained during the accident.
The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma,
performed toxicology tests on specimens obtained during each autopsy. The flight instructor's
toxicology results were negative for carbon monoxide, ethanol, and all tested drugs and
medications.
The pilot receiving instruction's toxicology results detected dextromethorphan and its
metabolite dextrorphan, doxylamine, and ibuprofen in urine. Dextromethorphan, dextrorphan,

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CEN17FA111

 and doxylamine were also detected in blood at levels too low to quantify accurately. The testing
also identified 35.75 µg/ml of acetaminophen in urine. Acetaminophen is a fever treatment and
analgesic commonly available over the counter with the name Tylenol. Ibuprofen is also used
to treat pain and fever and is commonly available over the counter with the names Advil and
Motrin. Acetaminophen and ibuprofen are not considered impairing. Dextromethorphan is a
cough suppressant found in many over the counter cough and cold preparations. In typical
doses, dextromethorphan is not considered impairing. Doxylamine is a sedating antihistamine
available in a variety of over the counter cold products and sleep aids.
Tests And Research
The airplane was equipped with a Garmin G1000 avionics suite; however, the multifunction
display was not equipped with a memory card that could have recorded flight parameters
during the flight. The airplane operator confirmed that none of their G1000-equipped Cessna
172S airplanes had a memory card installed.
An Apple iPad Air, Apple iPad Air 2, and an Apple iPhone 5S were recovered from the wreckage
and submitted to the NTSB Vehicle Recorder Laboratory for forensic examination. Attempts to
repair the damaged Apple iPad Air were unsuccessful, and no information was recovered from
the device. The damaged Apple iPad Air 2 was repaired, but forensic efforts to access the
password-protected data were not successful. The damaged Apple iPhone 5S was repaired, and
photos and an encrypted backup were recovered from the device. The recovered photos were
not pertinent to the investigation, and the encrypted backup precluded further review of the
device.
Additional Information
According to the airplane's Pilot Operating Handbook (POH), intentional spin maneuvers are
approved when the airplane is operated within the specified limits of utility category. The POH
indicates that at least 1,000 ft of altitude loss should be allowed for a one-turn spin and
recovery, while a six-turn spin and recovery may require more than twice that amount. Full aft
elevator and full rudder applied in the direction of the spin should be maintained until spin
recovery is initiated. An inadvertent relaxation of either of these controls could result in the
development of a nose-down spiral (instead of a spin). The POH stipulates that when training
in spins and spin recoveries, a one- or two-turn spin is adequate and should be used. During
the first two turns, the spin will progress to a rapid rate of rotation and a steep nose-down
attitude. Proper application of recovery controls will yield prompt recoveries within a quarter
turn. During extended spins of two to three turns or more, the spin will tend to change into a
nose-down spiral, particularly to the right. In the event of a nose-down spiral, a recovery
should be accomplished promptly but smoothly by leveling the wings and recovering from the
resulting dive.

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CEN17FA111

 Administrative Information
Investigator In Charge (IIC):

Andrew T Fox

Adopted Date:

11/05/2018

Additional Participating Persons:

Phillip Potter; Federal Aviation Administration, Denver FSDO; Denver, CO
Peter Basile; Textron Aviation; Wichita, KS
Troy Helgeson; Lycoming Engines; Milliken, CO

Publish Date:

11/05/2018

Note:

The NTSB traveled to the scene of this accident.

Investigation Docket:

http://dms.ntsb.gov/pubdms/search/dockList.cfm?mKey=94777

The National Transportation Safety Board (NTSB), established in 1967, is an independent federal agency mandated
by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine
the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate
the safety effectiveness of government agencies involved in transportation. The NTSB makes public its actions and
decisions through accident reports, safety studies, special investigation reports, safety recommendations, and
statistical reviews.
The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence
or use of any part of an NTSB report related to an incident or accident in a civil action for damages resulting from a
matter mentioned in the report.

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