# NTSB ANC10LA012: Piper PA-12, N3233M, Gulkana, AK, January 14, 2010

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 14, 2010, 10:30 local (14:30 UTC)
- Place: Gulkana, AK
- Coordinates: 55.920387, -159.490341 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=55.9204&lon=-159.4903&mi=10
- Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping)
- Defining event: [Taxi: Ground collision](https://openairdocs.org/ntsb-events/200)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report May 28, 2010
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- Parties: FAA
- NTSB case key (mKey): 75270
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC10LA012
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75270/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75270
- Page: https://openairdocs.org/ntsb/ANC10LA012

## Probable cause

The pilot's selection of unsuitable terrain for landing, which resulted in structural damage to the airplane during landing.

## Findings

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

- [Fuselage: frames (main fuselage)](https://openairdocs.org/ntsb-findings/01035311): Aircraft › Aircraft structures · Damaged/degraded; cases with it: [Piper PA-12, 2 cases](https://openairdocs.org/ntsb-findings/01035311/cases.md?model=7101202), [All aircraft, 8 cases](https://openairdocs.org/ntsb-findings/01035311/cases.md)
- [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Piper PA-12, 18 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7101202), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md)
- [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Effect on equipment; cases with it: [Piper PA-12, 5 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=7101202), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md)
- [Runway/land/takeoff/taxi surface](https://openairdocs.org/ntsb-findings/03023000): Environmental issues › Physical environment · Decision related to condition; cases with it: [Piper PA-12, 3 cases](https://openairdocs.org/ntsb-findings/03023000/cases.md?model=7101202), [All aircraft, 253 cases](https://openairdocs.org/ntsb-findings/03023000/cases.md)

## Sequence of events

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

- [Taxi: Ground collision](https://openairdocs.org/ntsb-events/200) (defining event); cases with it: [Piper PA-12, 4 cases](https://openairdocs.org/ntsb-events/200/sequence.md?model=7101202), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md)

## Analysis

The commercial pilot was on a passenger flight when the accident occurred. The pilot said that, due to the cold outside temperature, he departed with the airplane's oil cooler cover in place. He said that the engine temperature increased and that he decided to land and remove the oil cooler cover. He then landed on a snow-covered lake and after landing he continued laying down tracks in the snow to aid in his departure. While laying down tracks the airplane's skis hit a ridge hidden under the snow. The pilot then examined the airplane and found that a fuselage frame tube had broken near the right main landing gear attachment. The pilot said that there were no mechanical problems with the airplane prior to the accident.

## Factual narrative

On January 14, 2010, about 1030 Alaska standard time, a wheel ski-equipped Piper PA-12 Airplane, N3233M, sustained substantial damage after landing on a snow-covered lake, about 15 miles southeast of Gulkana, Alaska. The airplane was being operated by Copper Valley Air Service Inc., Glennallen, Alaska, as a visual flight rules (VFR) passenger flight under Title 14, CFR Part 135, when the accident occurred. The commercial pilot and sole passenger were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight departed the Gulkana Airport about 1030 for McCarthy, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on January 15, the pilot said that due to the cold outside temperature, he departed Gulkana with the airplane's oil cooler cover in place. He said after departing, the engine temperature increased significantly, and he decided to land and remove the oil cooler cover. He reported that he chose a snow-covered lake for landing, and that after landing, he continued laying down tracks in the newly fallen snow to aid in his departure. The pilot said while laying down tracks the airplane's skis hit a ridge hidden under the snow. He said he examined the airplane and found a fuselage frame tube had broken near the right main landing gear attachment. He said he called for another airplane to pickup his passenger. The pilot said there were no mechanical problems with the airplane prior to the flight.

## Aircraft

- Registration: [N3233M](https://openairdocs.org/aircraft/N3233M), registered now, S/N 12-2027, built 1947 (OpenAirDocs)
- Reported make and model: PIPER PA-12
- Registry model: [Piper PA-12](https://openairdocs.org/model/piper-pa-12) (registry code 7101202) (OpenAirDocs)
- Registry engine: [Lycoming O-320-A2B](https://openairdocs.org/engine/lycoming-o-320-a2b) (registry code 42101, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 12-2027
- Airframe hours: 3114
- Engines: LYCOMING O-320-A2B 150 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Operator: Copper Valley Air Service LLC
- Registered owner: Copper Valley Air Service LLC
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, July 16, 2009
- Departed: PAGK, Gulkana, AK
- Destination: PAMX, McCarthy, AK
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; injuries: none; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review May 10, 2009; seat: front; flight hours: 8,400 total, 2,100 in this make and model, 7,600 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: -9 °F
- Altimeter: 29.45 inHg
- Observed at: GKN, 15 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 20100114025939A](https://openairdocs.org/incident/20100114025939A), Jan 14, 2010: Piper PA-12, Glenallen, AK, Substantial damage. Aircraft landed on frozen lake, during taxi the right landing gear struck a unforseen snow covered snow bank damaging the right gear attachment point.

## Other investigations on N3233M (3)

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 GAA17CA511](https://openairdocs.org/ntsb/GAA17CA511), Aug 26, 2017: Piper PA 12 (N3233M), Gulkana, AK, substantial damage. Probable cause: The pilot’s inadequate in-flight fuel planning, which resulted in a loss of engine power due to fuel exhaustion.
- [NTSB ANC07LA018](https://openairdocs.org/ntsb/ANC07LA018), Feb 1, 2007: Piper PA-12 (N3233M), Glennallen, AK, substantial damage. Probable cause: The pilot's failure to maintain adequate airspeed to preclude a stall while maneuvering, which resulted in an uncontrolled descent and subsequent collision with terrain. Factors contributing to the…
- [NTSB ANC02LA113](https://openairdocs.org/ntsb/ANC02LA113), Sep 3, 2002: Piper PA-12 (N3233M), Chickaloon, AK, substantial damage. Probable cause: The pilot's failure to maintain control of the airplane during the landing roll, which precipitated a nose over.

## Docket (1 files)

The files NTSB released with the investigation on March 8, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75270. 1.1 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40326688&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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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