# NTSB DEN85LA076: Piper PA-18, N3777P, Thompson Falls, MT, February 11, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: February 11, 1985, 10:30 local (17:30 UTC)
- Place: Thompson Falls, MT
- Coordinates: 47.560512, -115.439445 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.5605&lon=-115.4394&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16633
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85LA076
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16633/pdf
- Page: https://openairdocs.org/ntsb/DEN85LA076

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power(total) - nonmechanical, maneuvering
  - weather condition - carburetor icing conditions (contributing factor)
  - carburetor heat - improper use of, pilot in command (cause)
  - procedures/directives - not followed, pilot in command (cause)
  - performance data - not understood, pilot in command (cause)
- Forced landing, descent - emergency
- Nose over, landing - flare/touchdown
  - terrain condition - snow covered (contributing factor)

## Analysis

THE ACFT NOSED OVER DURING A FORCED LNDG ON TERRAIN COVERED BY 20 INCHES OF SNOW. THE FLT WAS ON DEER SURVEY FLT THE PLT TOLD OF IMPROPER USE OF THE CARB HEAT CONTROL DURING A PERIOD OF'PERFECT' ICING CONDITIONS. THE PLTS REDUCTION OF POWER DURING MANEUVERING ALSO CONTRIBUTED TO THE BUILD UP OF ICE IN THE CARBURETOR. THE PLT WROTE IN HIS STATEMENT UNDER PREVENTATIVE RECOMMENDATIONS THAT HE SHOULD HAVE BEEN MORE AWARE OF GETTING BEHIND THE 'HEAT CURVE' OF THE ENG.

## Aircraft

- Registration: [N3777P](https://openairdocs.org/aircraft/N3777P), registered now, S/N 18-4665, built 1959 (OpenAirDocs)
- Reported make and model: PIPER PA-18
- Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 18-46665
- Airframe hours: 2375
- Engines: LYCOMING O-320 150 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial observation, Part 91
- Registered owner: David Bennett
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, October 15, 1984, 55 hours before
- Departed: MSO, THOMAS FALLS, MT
- Airport: Unknown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; commercial; airplane ratings: single-engine land, single-engine sea, multi-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 1,710 total, 1,000 in this make and model, 30 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 5 knots
- Visibility: 5 statute miles
- Lowest ceiling: 4,000 ft overcast
- Temperature: 30 °F
- Observed at: MSO

## 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 19850211004169A](https://openairdocs.org/incident/19850211004169A), Feb 11, 1985: Piper PA18150, Thompson Falls, MT, Substantial damage. Circled wildlife, did not use carburetor heat adequately. Engine quit, landed in deep snow, flipped over on back.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.