What happened
On a mission for Marine Transport Squadron 152, an aircraft departed El Toro Airbase at 10:30 local time, traveling toward Alameda NAS. The flight was transporting United States Marines from Camp Pendleton to Hickam Field, accompanied by a crew of five.
During the approach to the destination, air traffic control directed the pilot into a holding pattern lasting approximately 30 minutes. At 13:42 local time, while operating in marginal weather conditions, the aircraft began its descent at an altitude of 3,500 feet. During this phase of flight, the plane struck the slope of Mt Sunol Ridge, situated roughly 21 miles southeast of Alameda Airbase. The impact occurred approximately 200 feet below the mountain's summit. The crash resulted in 40 fatalities, with no survivors among the passengers or crew.
Findings
Investigations into the accident revealed that the collision was driven by errors and omissions by the flight crew. Specifically, the crew failed to adhere to established approach procedures and misidentified signals from local beacons. These navigational mistakes led to a premature descent and caused the aircraft to drift six miles northeast of its intended path. Reduced visibility caused by cloud cover was also identified as a contributing factor to the accident.