The DC-3 aircraft left Hawthorne (HTH) at 03:50 PST on a VFR flightplan for Burbank (BUR) and Long Beach (LGB), USA. Last contact with the flight was at 04:06 when the crew contacted the Tonopah Flight Service Station, and requested that their flight plan be opened. At 05:10, some 20 km West of Lone Pine, the airplane impacted the face of a sheer cliff on the east slope of the Mount Whitney at an elevation of 11,770 feet m.s.l. (3587 m). The main body of the wreckage slid down the cliff and came to rest 500 feet back from the cliff. An extensive ground and air search was launched after the aircraft was declared missing. Due to heavy snow accumulations on the ground, low clouds throughout the search period, and extremely hazardous terrain, the aircraft was not located until August 8, 1969. PROBABLE CAUSE: “The deviation from the prescribed route of flight, as autorized in the company’s FAA-approved operations specifications, resulting in the aircraft being operated under IFR weather conditions, in high mountainous terrain, in an area where there was a lack of radio navigation aids.”