ANC25FA001

NTSB accident investigation · Cessna 180 · Big Lake, AK · October 5, 2024

Accident · FatalClass 3 · FieldPreliminary report
Date
October 4, 2024, 17:30 local (Oct 5, 2024, 01:30 UTC)
Place
Big Lake, AK · Butterfly lake
Injuries
1 fatal, 1 serious
Damage
Substantial damage
Phase of flight
Unknown
Aircraft
N4631UCessna 180
Defining event
Unknown: Loss of control on ground
Weather
Visual (VMC) · Day
Status
Investigation ongoing
Investigation class
Class 3
NTSB office
Alaska Regional Office
Parties
FAA
FAA report
20241004014389A
Case key
195259

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Preliminary report

What NTSB knew early in the investigation. It may change in the final 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 is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Aircraft

Registration
N4631U
Reported as
Cessna 180
Category
Airplane
Serial number
18051331
Built
1963
Damage
Substantial damage
Flight
Personal · Part 91
Destination
LHD · Anchorage, AK

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

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.

Other investigations on N4631U · 3

Matched to the same aircraft by N-number and date.