Casualties unknown

1990-07-27: Lake LA-250 (N14004) — Rawlins, WY

Rawlins, WY, US

On July 27, 1990, a Lake LA-250 (registration N14004) was involved in an aviation accident near Rawlins, WY. Investigators recorded the probable cause as: The pilot's decision to turn toward rising terrain to find slope lift while encountering sink at a high density altitude, which resulted in insufficient terrain clearance. 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 1781061362Data APIEditorial standards

A Lake Amphibian aircraft collided with rising terrain after the pilot encountered unexpected sink while attempting to gain slope lift at a density altitude of approximately 9,070 feet.

What happened

The pilot of the Lake Amphibian initiated takeoff and subsequently turned toward an area of rising terrain. The maneuver was intended to locate slope lift, which the pilot anticipated would be available due to the prevailing wind conditions at the time. However, instead of gaining altitude as expected, the aircraft encountered sink. This loss of lift resulted in insufficient terrain clearance for the pilot to execute a course reversal. Consequently, the aircraft collided with the terrain.

The investigation

Investigation data indicated that the density altitude at the time of the accident was approximately 9,070 feet. This high density altitude likely contributed to the reduced performance capabilities of the aircraft, exacerbating the effects of the sink encountered during the maneuver.

Findings

The primary factors leading to the accident were the encounter with sink and the resulting insufficient terrain clearance. The high density altitude of approximately 9,070 feet was a significant contributing factor to the aircraft's inability to maintain safe altitude during the attempted lift-seeking maneuver.

Probable cause

The pilot's decision to turn toward rising terrain to find slope lift while encountering sink at a high density altitude, which resulted in insufficient terrain clearance.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X23844. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.