# NTSB ANC25FA001: Cessna 180, N4631U, Big Lake, AK, October 5, 2024

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Class 3 · Field · Preliminary report
- Date: October 4, 2024, 17:30 local (Oct 5, 2024, 01:30 UTC)
- Place: Big Lake, AK · Butterfly lake
- Coordinates: 61.598886, -150.08947
- Nearby events: https://openairdocs.org/map.md?lat=61.5989&lon=-150.0895&mi=10
- Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping)
- Defining event: [Unknown: Loss of control on ground](https://openairdocs.org/ntsb-events/230)
- Highest injury: Fatal
- Injuries: 1 fatal, 1 serious
- Status: Investigation ongoing
- Investigation class: Class 3
- NTSB office: Alaska Regional Office
- Parties: FAA
- NTSB case key (mKey): 195259
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC25FA001
- NTSB preliminary report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195259/pdf
- Page: https://openairdocs.org/ntsb/ANC25FA001

## Preliminary report

On October 4, 2024, about 1730 Alaska daylight time, a float-equipped Cessna 180 airplane, N4631U, sustained substantial damage when it was involved in an accident near Big Lake, Alaska. The pilot was fatally injured, and one passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight. According to the passenger, the airplane was departing from East Butterfly Lake, near Big Lake for a return flight to the Lake Hood Seaplane Base (LHD), Anchorage, Alaska. The passenger reported that just before starting their northerly takeoff run, strong, gusty, variable wind conditions prevailed. During takeoff from the lake, as the airplane passed low over an area of tree-covered terrain, a sudden gust of wind pushed the airplane towards the trees. The airplane’s right wing subsequently collided with a stand of tall trees, and the airplane came to rest inverted in the lake, partially submerged (See figure 1). Figure 1. Accident airplane, N4631U, at the accident site. (Alaska State Trooper Photo) A detailed wreckage examination is pending after the airplane is recovered from the waters of East Butterfly Lake.

## Sequence of events

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

- [Unknown: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Cessna 180G, 5 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2072616), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md)

## Aircraft

- Registration: [N4631U](https://openairdocs.org/aircraft/N4631U), registered now, S/N 18051331, built 1963 (OpenAirDocs)
- Reported make and model: CESSNA 180
- Registry model: [Cessna 180G](https://openairdocs.org/model/cessna-180g) (registry code 2072616) (OpenAirDocs)
- Registry engine: [Continental O-470 series](https://openairdocs.org/engine/continental-o-470-series) (registry code 17026, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 18051331
- Year built: 1963
- Damage: Substantial damage
- Flight: Personal, Part 91
- Destination: LHD, Anchorage, AK

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 15 knots, gusting 28
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 48 °F, dew point 32 °F
- Altimeter: 29.07 inHg
- Observed at: PAWS, 17 nm away
- METAR: PAWS 050156Z AUTO 09015G28KT 10SM CLR 09/00 A2907 RMK AO2 PK WND 10031/0119 SLP845 T00940000

## 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 20241004014389A](https://openairdocs.org/incident/20241004014389A), Oct 4, 2024: Cessna 180G, Big Lake, AK, Substantial damage, 1 fatal. The early evening hours the day of the accident had strong, gusty and variable winds in the area. The lake the aircraft was preparing to depart from was…

## Other investigations on N4631U (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 ANC08CA090](https://openairdocs.org/ntsb/ANC08CA090), Jul 28, 2008: Cessna 180G (N4631U), Anchorage, AK, substantial damage. Probable cause: The pilot's failure to maintain directional control during landing. Contributing to the accident was an inadvertent ground-loop.
- [NTSB ANC76DAH89](https://openairdocs.org/ntsb/ANC76DAH89), Sep 23, 1976: Cessna 180 (N4631U), Kulik Lake, AK, substantial damage
- [NTSB FTW70D0189](https://openairdocs.org/ntsb/FTW70D0189), Aug 29, 1969: Cessna 180G (N4631U), Leeville, LA, 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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