What happened
During a nighttime descent under marginal weather conditions characterized by low clouds, the crew received instructions from Air Traffic Control to divert to Los Angeles International Airport for a safe ILS approach. While navigating through dark conditions and fog near the Puente Hills, the aircraft struck the slope of Mt Puente, located approximately two miles east of Whittier. The wreckage was discovered several hours after the impact. There were 29 fatalities among the occupants.
Findings
Investigations into the accident identified several contributing factors related to flight operations and crew limitations. The investigation determined that the pilot descended below the minimum altitude authorized by ATC, attempting an approach at a height insufficient to clear the local terrain. Specifically, the aircraft descended significantly lower than the required minimum altitude prescribed between the Downey fan marker and the Riverside range.
Additional findings noted regulatory discrepancies regarding the crew. The command pilot was operating in violation of medical certificate limitations that restricted his duties to company check pilot roles. Furthermore, the co-pilot had exceeded prescribed flight time limitations during the mission. While weather conditions at Los Angeles International Airport were suitable for an ILS approach, the presence of fog near the mountains contributed to the hazardous flying environment.