# NTSB WPR21FA045: Cessna 177, N34633, Langley, WA, November 11, 2020

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Class 3 · Field · Final report
- Date: November 11, 2020, 11:44 local (19:44 UTC)
- Place: Langley, WA
- Coordinates: 48.017512, -122.43772 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=48.0175&lon=-122.4377&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach: Loss of control in flight](https://openairdocs.org/ntsb-events/240)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: Lycoming, Textron Aviation, Federal Aviation Administration
- SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs)
- NTSB case key (mKey): 102268
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21FA045
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102268/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102268
- Page: https://openairdocs.org/ntsb/WPR21FA045

## Probable cause

The flight instructor’s failure to maintain airspeed, which resulted in an aerodynamic stall and subsequent loss of control while attempting to conduct an emergency landing. Contributing to the accident was a total loss of engine power as a result of carburetor icing.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Cessna 177B, 25 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=2073708), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)
- [Temp/humidity/pressure: conducive to carburetor icing](https://openairdocs.org/ntsb-findings/03031030): Environmental issues › Conditions/weather/phenomena · Effect on operation (probable cause); cases with it: [Cessna 177B, 2 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md?model=2073708), [All aircraft, 435 cases](https://openairdocs.org/ntsb-findings/03031030/cases.md)
- [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Cessna 177B, 7 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=2073708), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md)
- [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Cessna 177B, 2 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=2073708), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 177B, 5 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2073708), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Cessna 177B, 9 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073708), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md)
- [Enroute: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna 177B, 10 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2073708), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Approach: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Cessna 177B, 8 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=2073708), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md)
- [Approach: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 177B, 20 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073708), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

About 16 minutes after takeoff, at 6,500 ft above mean sea level , the airplane’s groundspeed decreased and the airplane started to descend. Shortly thereafter, the flight instructor reported to air traffic control that they were declaring an emergency because they were at full power and rpm setting, and about to lose the engine. They were also unable to maintain altitude. The airplane continued southeast for about 2 miles when it made a left turn east and then back to the southeast. The flight instructor reported they had a little power but were still descending. He further stated that the engine would not stay on for very long and they were at idle power. The controller asked if he had carburetor heat on and he replied “affirmative.” Shortly thereafter, the flight instructor reported that they did not have engine power and they were going directly to nearby Whidbey Air Park, Langley, Washington. The airplane crossed and flew over a highway before turning north to the airport. Shortly thereafter, the flight instructor stated they were diverting off-airport and the airplane track turned right away from the airport. However, about 15 seconds later he reported the airport insight and the airplane’s track changed back toward the airport. There was no further communication from the accident airplane. The last radar point was over the runway at an altitude of about 300 ft. A witness reported who was at the airport observed the accident airplane about pattern altitude passing from west to east. The accident airplane continued slightly east of the airport before it made a left turn to a northwest heading. It appeared as if the airplane was “porpoising,” continuously nosing up and down. He noted that the propeller was not turning and there were no audible engine sounds. As the airplane passed over the runway the left wing dropped, and the airplane spun out of sight behind the trees and hangars. Shortly thereafter, the witness heard the impact. The airplane came to rest about 153 ft west of the runway surface against trees that were about 65 ft tall. The witness account and the condition of the wreckage were indicative of the flight instructor’s failure to maintain airspeed, which resulted in an aerodynamic stall and subsequent spin. A postaccident airframe and engine examination did not reveal any anomalies that would have precluded normal operations. The airplane’s engine monitoring system revealed the carburetor temperature had been steadily decreasing from 31°F during the accident flight. When the carburetor temperature reached 17°F there was an abrupt decrease in fuel flow and a corresponding reduction in exhaust gas temperatures. For the remainder of the flight, the exhaust and cylinder head temperatures slowly decreased, and the carburetor temperature slowly increased. The fuel flow spiked several times but immediately decreased. The nearest weather reporting station reported the temperature as 6°C and dewpoint, 2°C. When plotted on the carburetorice chart, this temperature dewpoint spread is consistent with serious icing at cruise power. Therefore, it is likely carburetor ice was building during the accident flight and it eventually starved the engine of fuel.

## Factual narrative

On November 11, 2020, at 1144 Pacific standard time, a Cessna 177B airplane, N34633, was substantially damaged when it was involved in an accident near Whidbey Air Park (W10), Langley, Washington. The private pilot and flight instructor were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Radar and air traffic control data indicated that, earlier in the day, the airplane flew from Boeing field (BFI), Seattle, Washington, to Bellingham International Airport (BLI) Bellingham, Washington. About 1110, the airplane departed BLI and flew south over Whidbey Island toward BFI. The airplane climbed to about 6,500 ft mean sea level (msl) for about 16 minutes when the airplane’s groundspeed decreased, and the airplane started to descend. Shortly thereafter the flight instructor reported to air traffic control that they were declaring an emergency, and the airplane’s transponder code changed to 7700. He further reported that they had “full power and RPM setting, and about to lose the engine.” Air traffic control told the flight instructor to maintain current heading, but he informed them the airplane was “unable to maintain altitude.” The flight instructor reported they were at “1100 rpm unable to hold altitude with max power, about 75.” The controller directed the pilot toward W10 and the radar track showed a left turn toward the east then southeast. Shortly thereafter, the flight instructor reported they “had a little bit of power but are still descending at 5,000 [ft].” The controller provided the location of Snohomish County Airport; Paine Field (PAE), which was 12 miles away, and asked if they could make it there; the flight instructor replied, “we could try, the engine does not stay on for very long, we are back at idle.” The controller asked if he had carburetor heat on and he replied “affirmative.” The controller continued to provide positions for PAE and W10. After temporarily loosing radio contact, the flight instructor reported that they were unable to make PAE with no engine; they are going directly to W10. The airplane crossed over highway 525 and flew over it for about 44 seconds then turned northbound toward W10. The flight instructor stated they were diverting off-airport and the airplane track turned right. However, about 15 seconds later, he reported the airport insight and the airplane’s track changed north toward the airport. There was no further communication from the accident airplane. The last radar point was over the runway at an altitude of about 300 ft. A witness who landed at W10 about 1 hour and 15 minutes before the accident reported that mist rising from the trees made it harder than normal to find the airport. He was standing at the northwest corner of the airport when he observed the accident airplane about pattern altitude passing from west to east. The accident airplane continued slightly east of W10 before it made a left turn to a northwest heading. It appearedas if the airplane was “porpoising,” continuously nosing up and down. He noted that the propeller was not turning and there were no audible engine sounds. As the airplane passed over the runway the left wing dropped, and the airplane spun out of sight behind the trees and hangars. Shortly thereafter the witness heard the impact. The airplane’s engine monitoring system revealed the carburetor temperature had been steadily decreasing from 31°F during the accident flight. When the carburetor temperature reached 17°F there was an abrupt decrease in fuel flow and a corresponding reduction in exhaust gas temperatures. For the remainder of the flight the exhaust and cylinder head temperatures slowly decreased, and the carburetor temperature slowly increased. The fuel flow spiked several times, but immediately decreased. The Island County Corner’s Officer located in Coupeville, Washington, performed an autopsy of the flight instructor. The flight instructor’s cause of death was multiple traumatic injuries. The Federal Aviation Administration (FAA) Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the flight instructor with positive results for azacyclonol and fexofenadine, both of which are approved for flight per the FAA. The Island County Corner’s Officer located in Coupeville, Washington, performed an autopsy of the pilot. The pilot’s cause of death was multiple traumatic injuries. Toxicology on specimens from the pilot were positive for Irbesartan, which his approved for flight per the FAA. The nearest weather reporting station was about 9 nautical miles southeast of the accident site. At 1153, the temperature was reported as 6°C and dewpoint, 2°C. When plotted on the Federal Aviation Administration (FAA) carburetor ice chart, this temperature dewpoint spread is consistent with serious icing at cruise power. FAA Special Airworthiness Information Bulletin (CE-09-35) – Carburetor Icing Prevention, stated that: …pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. Icing can occur in the carburetor at temperatures above freezing because vaporization of fuel, combined with the expansion of air as it flows through the carburetor, (Venturi Effect) causes sudden cooling, sometimes by a significant amount within a fraction of a second. Carburetor ice can be detected by a drop in rpm in fixed pitch propeller airplanes and a drop in manifold pressure in constant speed propeller airplanes. In both types, usually there will be a roughness in engine operation. The airplane came to rest about 153 ft west of the runway surface against trees that were about 65 ft tall. The bark was scraped off one side of a tree about mid height extending down to the airplane, which came to rest nose low at the base of the tree. Both the left and right wings remainedattached to the fuselage and their leading edges exhibited aft crush damage. A tree shaped indent was also noted along the top of the right wing. Both the left and right fuel tanks were breached. The cabin area sustained extensive impact damage. The empennage remained intact but exhibited impact related damage. During a postaccident examination, flight control continuity was established throughout the airframe. The fuel strainer bowl exhibited some minor debris, and the screen was clear. The airframe fuel pump was functionally tested with no anomalies were noted. The fuel flow transducer was removed and clear of debris. Compressed air was applied to each fuel line and vent lines; all were clear of debris or blockages. The wing fuel tank finger screens were examined and clear of debris. The engine did not exhibit any visual indications of catastrophic failure. The engine remained attached to the firewall. Both the induction and exhaust systems sustained crush damage, consistent with impact. The exhaust was removed and there was no evidence of any internal damage or obstructions. The propeller, upper spark plugs, and fuel pump were removed. The crankshaft was rotated using a hand tool attached to an accessory mounting pad. Thumb compression was obtained on all cylinders. Movement of all intake and exhaust rocker arms was observed and no abnormal coloration was noted. The single-drive dual magneto was removed from the engine and rotated by hand; spark was obtained on all eight ignition leads. The ignition harness sustained impact damage and was unable to be functionally tested. The lower spark plugs were removed. All eight spark plugs exhibited ‘severe worn-out’ signatures. All four cylinders were borescoped and all exhibited normal operating signatures. The carburetor sustained impact damage. The fuel inlet screen was clear of debris. The throttle remained secured to the throttle arm, and it moved freely from stop to stop. The mixture arm was separated from the mixture control shaft. The mixture control shaft was bent, consistent with impact damage. The carburetor was disassembled; the internal floats and needle valve were intact and undamaged. The fuel pump, and propeller governor were disassembled; no anomalies were noted. One propeller blade remained attached to the propeller hub and was mostly straight. The second blade was partially separated and bent aft at the root; it exhibited various striations on the chamber side of the blade. The single-drive dual magneto was removed from the engine, and it functionally tested normal. The throttle cable was removed from the airplane and sent to the National Transportation Safety Board laboratory. The cable fracture features of the sheath and strands were consistent with overstress fracture. No other features consistent with other fracture modes were observed. All other features detailed were consistent with post-fracture damage.

## Aircraft

- Registration: [N34633](https://openairdocs.org/deregistered/N34633-2021-07-27), registration cancelled 2021-07-27, S/N 17701913, built 1973 (OpenAirDocs)
- Reported make and model: CESSNA 177 (B)
- Registry model: [Cessna 177B](https://openairdocs.org/model/cessna-177b) (registry code 2073708) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 17701913
- Year built: 1973
- Airframe hours: 6313
- Engines: Lycoming O-360-A1F6D 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Registered owner: Lazy Eight Flying Club Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, April 6, 2020, 106 hours before
- Departed: BLI, Bellingham, WA
- Destination: BFI, Seattle, WA
- Airport: W10, Whidbey Air Park, runway 34, 2,470 × 25 ft, asphalt
- Equipment: Unknown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 78; injuries: fatal; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: left; toxicology performed; flight hours: 312 total, 100 in this make and model
- Flight instructor; age 25; injuries: fatal; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review October 8, 2020; seat: right; toxicology performed; flight hours: 324 total, 12 in this make and model, 224 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: 4,400 ft overcast
- Temperature: 43 °F, dew point 36 °F
- Altimeter: 3019.00 inHg
- Observed at: PAE, 9 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20201111022169A](https://openairdocs.org/incident/20201111022169A), Nov 11, 2020: Cessna 177B, Langley, WA, Destroyed, 2 fatal. Aircraft was on instrument flight plan enroute from bellingham, WA (bli) to Boeing field, WA (bfi). While enroute, PIC reported loss of engine power and unable…

## Other investigations on N34633 (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB SEA02LA147](https://openairdocs.org/ntsb/SEA02LA147), Aug 1, 2002: Cessna 177B (N34633), Elma, WA, substantial damage. Probable cause: The pilot's failure to maintain directional control during a bounced landing and recovery resulting in the aircraft's departing the runway. Contributing factors were the high brush/vegetation the…

## Docket (21 files)

The files NTSB released with the investigation on July 19, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102268. 59.3 MB in all.

- Materials laboratory factual report (item 1, PDF, 23 pages, 36 photos, 21.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12563839&FileExtension=pdf&FileName=21-055%20-%20Materials%20Lab%20Factual%20Report%20(WPR21FA045)-Rel.pdf
- Engine data monitor - specialist's factual report (item 2, PDF, 5 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12282768&FileExtension=pdf&FileName=Engine%20Data%20Monitor%20-%20Specialist%27s%20Factual%20Report-Rel.pdf
- Attachment 1 to engine data monitor - specialist's factual report -- tabular data (item 3, CSV, 639 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12282979&FileExtension=csv&FileName=Attachment%201%20to%20%20Engine%20Data%20Monitor%20-%20Specialist%27s%20Factual%20Report%20--%20Tabular%20Data-Rel.csv
- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 4, PDF, 9 pages, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11632684&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- Record of email - witness (item 5, PDF, 2 pages, 227 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11633024&FileExtension=pdf&FileName=ROE%20WItness-Rel.pdf
- Air traffic control recording (item 6, MP4, 6.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14071672&FileExtension=mp4&FileName=S46%2011-11-2020%20N34633%20FATAL-Rel.mp4
- ADS-B google earth (item 7, KMZ, 337 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11592817&FileExtension=kmz&FileName=20201111_A3D675_440069041-Rel.kmz
- On scene observations (item 8, PDF, 8 pages, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11615222&FileExtension=pdf&FileName=WPR21FA045%20On%20Scene%20Exam-Rel.pdf
- Airframe and engine examination observations (item 9, PDF, 7 pages, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12094582&FileExtension=pdf&FileName=examination%20notes%20with%20photos-Rel.pdf
- Additional on scene photos (item 10, PDF, 4 pages, 6.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12095005&FileExtension=pdf&FileName=additional%20on%20scene%20photos-Rel.pdf
- Magneto examination report - aircraft magneto service (item 11, PDF, 1 page, 32 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14070200&FileExtension=pdf&FileName=N34633%20Magneto%20Exam%20report-Rel.pdf
- FAA special airworthiness information bulletin (CE-09-35) a�� carburetor icing prevention (item 12, PDF, 3 pages, 111 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14070949&FileExtension=pdf&FileName=Carb%20Icing%20FAA%20Bulletin-Rel.pdf
- Autopsy record of memorandum - pilot (item 13, PDF, 1 page, 113 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14071909&FileExtension=pdf&FileName=Record%20of%20Memorandum%20auotpsy%20pilot-Rel.pdf
- Autopsy record of memorandum - flight instructor (item 14, PDF, 1 page, 113 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14071510&FileExtension=pdf&FileName=Record%20of%20Memorandum%20auotpsy%20CFI-Rel.pdf
- Statement of party representatives to NTSB investigation (item 15, PDF, 2 pages, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14071858&FileExtension=pdf&FileName=party%20form%20combined_Redacted-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 16, PDF, 1 page, 779 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14150712&FileExtension=pdf&FileName=N34633%20signed%20wreckage%20release_Redacted-Rel.pdf
- Toxicological report - flight instructor (item 17, PDF, 1 page, 692 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13182923&FileExtension=pdf&FileName=tox%20CFI%20printed_Redacted-Rel.pdf
- Toxicological report - pilot (item 18, PDF, 1 page, 675 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13182977&FileExtension=pdf&FileName=Tox%20pilot%20printed_Redacted-Rel.pdf
- Evidence control form - single drive dual magneto (item 19, PDF, 4 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14152268&FileExtension=pdf&FileName=Evidence%20Control%20Form%20Mags-Rel.pdf
- Evidence control form - throttle cable (item 20, PDF, 4 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14153158&FileExtension=pdf&FileName=Evidence%20Control%20Form%20throttle%20cable-Rel.pdf
- Evidence control form - jpi memory card (item 21, PDF, 3 pages, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14153091&FileExtension=pdf&FileName=Evidence%20Control%20Form%20Memory%20card-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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