On June 18, 1985, a Maule M-6-235 (registration N121A) operated by Alpine Air Service was involved in an aviation accident near Gibbonsville, ID. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot and two passengers on a two-hour aerial observation flight over mountainous terrain impacted the ground in a near-vertical attitude, consistent with an incipient stall. No airframe or powerplant malfunction was found.
Overview
A pilot and two passengers departed on a two-hour flight intended for aerial observation of mine sites. The aircraft operated in mountainous terrain under hot temperature conditions, which resulted in a high density altitude. There were no witnesses to the accident.
Flight Details
The flight was conducted for the purpose of observing mine sites from the air. The aircraft was flown in a geographic region with which the pilot was familiar, having operated the same aircraft in similar environmental conditions near the accident site for the previous year.
Accident Sequence
The aircraft descended and subsequently impacted the ground in a near-vertical attitude. This attitude is indicative of the initial phase of a stall. No witnesses were present to observe the final moments of the flight.
Investigation Findings
Examination of the wreckage revealed no evidence of any airframe or powerplant malfunction. The aircraft had been operating in mountainous terrain with high density altitude conditions due to hot temperatures.