# NTSB SEA85FA142: Maule M-6-235, N121A, Gibbonsville, ID, June 18, 1985

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: June 18, 1985, 17:38 local (23:38 UTC)
- Place: Gibbonsville, ID
- Coordinates: 45.599182, -113.890754 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.5992&lon=-113.8908&mi=10
- Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 3 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 40050
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA85FA142
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/40050/pdf
- Page: https://openairdocs.org/ntsb/SEA85FA142

## Sequence of events

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

- Loss of control - in flight, unknown
  - airspeed - not maintained, pilot in command (cause)
  - stall, pilot in command (cause)
  - terrain condition - mountainous/hilly (contributing factor)
  - weather condition - rising (contributing factor)
  - weather condition - high density altitude (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PLT AND TWO PASSENGERS DEPARTED ON A 2 HR FLT FOR THE PURPOSE OF CONDUCTING AERIAL OBSERVATION OF MINE SITES. THE ACFT WAS OPERATING IN MOUNTAINOUS TERRAIN DURING HOT TEMP CONDITIONS RESULTING IN A HIGH DENSITY ALT. THERE WERE NO WITNESSES TO THE ACCIDENT. THE ACFT DESCENDED TO AND IMPACTED THE GROUND IN A NEAR VERITCAL ATTITUDE INDICATIVE OF THE INITAL PHASE OF A STALL. THERE WAS NO EVIDENCE OF ANY AIRFRAME NOR POWERPLANT MALFUNCTION. THE PLT HAD BEEN OPERATING THE ACCIDENT ACFT IN THE GEOGRAPHIC AND ENVIRONMENTAL CONDITIONS NEAR THE ACCIDENT SITE FOR THE PREVIOUS YEAR.

## Aircraft

- Registration: N121A (not matched to a registry record)
- Reported make and model: MAULE M-6-235
- Category: Airplane
- Serial number: 7459C
- Airframe hours: 5802
- Engines: LYCOMING IO-540-W1A5D 235 horsepower reciprocating
- Damage: Destroyed
- Flight: Part 135
- Operator: Alpine Air Service
- Registered owner: Salmon Alpine Air Service
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, May 31, 1985, 334 hours before
- Departed: SMN, SALMON, ID

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; toxicology performed; flight hours: 3,555 total, 605 in this make and model, 183 in the last 90 days, 82 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 320° at 3 knots
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 81 °F, dew point 55 °F
- Observed at: SMN, 27 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 19850618029459A](https://openairdocs.org/incident/19850618029459A), Jun 18, 1985: Maule M6235, Gibbonsville, ID, Destroyed, 2 fatal. During aerial survey flight in mountainous area, aircraft struck trees. Density altitude and alcohol were factors.

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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