Casualties unknown

Airline Transport Pilot's Glacier Landing and Takeoff Turn Results in Collapse of Landing Gear (N4280Z)

Girdwood, AK, US

On January 21, 1989, a Piper PA-18 (registration N4280Z) operated by Gerald G. Chisum was involved in an aviation accident near Girdwood, AK. Investigators recorded the probable cause as: Tailwind and a 10-20 degree slope caused the aircraft to turn through the desired takeoff heading and slide sideways. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

An airline transport pilot landed up-slope on a glacier and initiated a down-slope takeoff turn. A tailwind and slope angle caused the aircraft to slide sideways, collapsing the right main landing gear and contacting the wing with the frozen surface.

Accident Description

An airline transport pilot executed a landing up-slope on a glacier. After landing, the pilot initiated a turn to take off down-slope. During this turn, a tailwind combined with a slope angle of 10 to 20 degrees caused the aircraft to rotate beyond the intended takeoff heading and slide sideways. The right ski dug into the snow, leading to the collapse of the right main landing gear. Subsequently, the right wing contacted the frozen surface. The accident site was at an elevation of approximately 4,400 feet above mean sea level.

Sequence of Events

The pilot first landed the aircraft while proceeding up-slope on the glacier. Following the landing, the pilot began turning the aircraft to align with a down-slope direction for takeoff. While turning, the presence of a tailwind and the significant slope (estimated at 10 to 20 degrees) caused the aircraft to continue turning past the desired takeoff heading. The aircraft then slid sideways. As the slide progressed, the right ski encountered deeper snow, exerting force on the right main landing gear, which collapsed. The right wing then struck the frozen surface.

Damage

The right main landing gear collapsed, and the right wing contacted the terrain. No further damage details were specified in the source.

Probable cause

Tailwind and a 10-20 degree slope caused the aircraft to turn through the desired takeoff heading and slide sideways.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X27520. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.