What happened
During a scheduled nighttime mail delivery, the aircraft experienced a simultaneous loss of power in both engines while flying through adverse weather. In an effort to reach the ground safely, the pilot initiated an emergency descent; however, the aircraft became uncontrollable and struck a mountain slope with a 40-degree incline.
Following the impact, search and rescue teams were deployed to locate the wreckage and the pilot. After several days of searching yielded no results, the operations were officially terminated as no sign of the plane or its occupant could be located. The debris was not discovered until March 21, 1969, when mountaineers spotted the site in the vicinity of Imnaha.
Findings
Investigations into the crash identified several contributing elements to the disaster. The primary cause was determined to be fuel exhaustion resulting from a compromised fuel system. Specifically, the investigation found that the tank caps, vents, and drains had not been properly secured, which allowed fuel to siphon out of the tanks. Additionally, the pilot's preflight preparations were deemed insufficient for the flight conditions.