What happened
On the westward leg of its international route from San Francisco to New York, the Boeing 707 known as 'Clipper Caribbean' was operating flight 001. After departing Bangkok-Don Mueang Airport, the aircraft proceeded toward Calcutta-Dum Dum Airport. The approach was conducted at night under challenging weather conditions characterized by rain and low cloud ceilings of approximately 400 feet.
During the descent, the crew configured the aircraft with flaps set to 50°. A critical error occurred when the flight crew misidentified the altimeter setting provided by air traffic control. Rather than applying the correct QNH of 993 mb, the crew utilized a QFE value of 29.93, which resulted in the aircraft descending roughly 360 feet below the intended glide path. The plane descended below the established decision height and struck treetops approximately 1,128 meters before reaching the runway threshold. The aircraft subsequently impacted the ground and caught fire about one kilometer from the runway, leading to the total destruction of the airframe.
Findings
The investigation identified that the accident was driven by improper IFR operation involving the incorrect use of flaps. Additionally, the crew's failure to correctly interpret the atmospheric pressure settings (QNH/QFE) led to the aircraft flying at an altitude below the required minimums for the approach.
In the accident, there were 6 fatalities (comprising one crew member and five passengers) and 20 injuries. A total of 37 individuals on board escaped without harm.