No fatalities

Aircraft Collides with Hilly Terrain After Encountering Downdraft During Caribou Spotting Flight (N3129S)

Iliamna, United States of AmericaFlight

On August 20, 1983, a De Havilland DHC-2 Beaver (registration N3129S) operated by Alaska North Flying Service was involved in an aviation accident near Iliamna, United States of America in flight. No fatalities were reported. Investigators recorded the probable cause as: Loss of control in flight due to a downdraft and inadequate altitude by the pilot in command, resulting in an in-flight collision with terrain due to mountainous/hilly terrain. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 1 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 2026-06-11Data APIEditorial standards

An aircraft encountered a downdraft and collided with hilly terrain while the pilot was spotting caribou. All five occupants were injured and the aircraft was destroyed.

Incident Details

During a caribou spotting flight, the aircraft entered a downdraft and subsequently collided with hilly terrain. The pilot reported that he was engaged in spotting caribou and settled into the side of a hill. Passengers indicated that the aircraft was approximately 300 feet above ground level before descending to ground contact. The collision resulted in injuries to all five occupants and the destruction of the aircraft.

Findings

The official investigation identified two occurrences. The first was a loss of control during maneuvering flight, attributed to a downdraft and the pilot's inadequate altitude. The second was an in-flight collision with terrain, also during maneuvering, due to mountainous/hilly terrain conditions.

Probable Cause

Loss of control in flight due to a downdraft and inadequate altitude by the pilot in command, resulting in an in-flight collision with terrain due to mountainous/hilly terrain.