# NTSB ANC89LA058: Cessna 185, N9850X, Trinity Lake, AK, April 12, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 11, 1989, 17:30 local (Apr 12, 1989, 01:30 UTC)
- Place: Trinity Lake, AK
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 28, 1990
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5175
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC89LA058
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5175/pdf
- Page: https://openairdocs.org/ntsb/ANC89LA058

## Probable cause

THE PILOT'S SELECTION OF UNSUITABLE TERRAIN ON WHICH TO LAND.

## Sequence of events

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

- Main gear collapsed, landing - roll
  - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause)
- Nose down, landing - roll

## Analysis

THE PILOT WAS ATTEMPTING A LATE AFTERNOON LANDING AT AN OFF AIRPORT LANDING SITE ON A SNOW COVERED LAKE. SHORTLY AFTER TOUCH DOWN, THE RIGHT MAIN LANDING GEAR SKI BECAME DETACHED FROM THE GEAR LEG. THE GEAR LEG WENT THROUGH THE SNOW AND INTO THE ICE BELOW, COLLAPSING THE RIGHT MAIN GEAR IN THE PROCESS. THE PILOT REPORTED THAT THE SNOW CONDITIONS WERE EXTREMELY WET, AND THAT DURING THE LANDING ROLL THE RIGHT MAIN SKI BECAME MIRED IN THE HEAVY SNOW, ULTIMATELY CAUSING THE SKI ATTACHMENT BOLTS TO FAIL AND ALLOWING THE GEAR LEG TO STRIKE THE ICE.

## Aircraft

- Registration: [N9850X](https://openairdocs.org/deregistered/N9850X-2018-02-28), registration cancelled 2018-02-28, S/N 1850050 (OpenAirDocs)
- Reported make and model: CESSNA 185
- Registry model: [Cessna 185](https://openairdocs.org/model/cessna-185) (registry code 2072802) (OpenAirDocs)
- Category: Airplane
- Serial number: 1850050
- Airframe hours: 3881
- Engines: CONTINENTAL IO-520 300 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Costley, Donald E.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 13, 1988, 97 hours before
- Departed: LHD, ANCHORAGE, AK

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; private; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 942 total, 703 in this make and model, 12 in the last 90 days, 7 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 5 knots
- Visibility: 60 statute miles
- Lowest ceiling: none
- Temperature: 39 °F

## 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 19890411007929A](https://openairdocs.org/incident/19890411007929A), Apr 11, 1989: Cessna 185, Trinity Lake, AK, Substantial damage. Landed on a snow covered lake. Snow was uneven wet, and heavy. Overload stripped off nuts holding ski to gear leg.

## Other investigations on N9850X (2)

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 ANC67A0031](https://openairdocs.org/ntsb/ANC67A0031), Sep 29, 1966: Cessna 185 (N9850X), Napakiak, AK, substantial damage
- [NTSB UNK64X2446](https://openairdocs.org/ntsb/UNK64X2446), Jun 23, 1964: Cessna 185 (N9850X), Kodiak, AK, substantial damage

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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