Pan Am Flight 001 Crash at Calcutta-Dum Dum Airport (N798PA)

Incident Overview and Route Details A four-engine aircraft named 'Clipper Caribbean' was operating Pan Am Flight 001 on a westward route from San Francisco to New York. The flight included intermediate stops in Honolulu, Hong Kong, Bangkok, Calcutta, New Delhi, Beirut, Istanbul, Frankfurt, and London. The accident occurred during the approach to Calcutta-Dum Dum Airport following a routine leg from Bangkok-Don Mueang Airport. The approach was conducted at night under marginal weather conditions, characterized by low clouds at 400 feet and rain showers. ## Approach and Impact Sequence During the approach, the crew deployed the flaps to 50 degrees and continued the descent. A critical error occurred when the crew misunderstood the atmospheric pressure value transmitted by air traffic control. Instead of setting the QNH value of 993 mb, the crew set the QFE at 29.93. This altimeter error caused the aircraft to descend 360 feet below the intended glide path. The aircraft continued below the decision height and struck tree tops located 1,128 meters short of the runway threshold. It subsequently impacted the ground and came to rest in flames one kilometer short of the runway. ## Casualties and Damage The accident resulted in the deaths of one crew member and five passengers. An additional 20 people were injured, while 37 others were unhurt. The aircraft was destroyed in the crash and subsequent fire. ## Official Probable Cause The official investigation identified improper IFR operation by the flying crew, specifically the misuse of the flaps. Additionally, the crew's misinterpretation of the approach QNH/QFE values caused the aircraft to complete the approach below the minimum prescribed altitude.