What happened
Following the deplaning of a passenger, the flight proceeded with 180 pounds of cargo on board. Prior to the accident, company pilots heard the pilot report that the destination was approximately 13 minutes away. After the aircraft failed to arrive as scheduled, company planes located the wreckage at an altitude of roughly 700 feet MSL, situated on the eastern side of a mountain pass that rises to 890 feet MSL.
The aircraft struck the terrain while flying on a 330-degree heading, perpendicular to the east-west axis of the canyon. The wreckage was found in a flat attitude, and investigators noted an absence of ground scars leading to the crash site. Environmental conditions at the time included a westerly wind of seven to nine knots, and visibility was sufficient, as other pilots reported that the mountain passes were not obscured by clouds. Photographs recovered from the pilot's camera, which were timestamped with the date of the accident, showed the canyon and the accident site at an altitude higher than where the photos were captured.
Findings
An examination of the aircraft revealed no mechanical anomalies, though the propeller blades showed evidence of torsional twisting and leading edge gouging. During the investigation of the pilot's flight bag, authorities discovered various over-the-counter medications used for asthma and cold symptoms, as well as several depressants and stimulants. Toxicological analysis confirmed the presence of certain over-the-counter drugs. The investigation concluded that the ingestion of these medications may have caused illness-related effects, such as sensory disturbance or distraction, which potentially contributed to the accident.