A de Havilland DH-106 Comet 1 passenger plane, operated by BOAC, was destroyed in an accident near Calcutta, India. All 43 on board were killed. The airplane operated on a return flight from London, UK to Singapore. On its return leg from Singapore it landed at Calcutta-Dum Dum Airport at 15:10 hrs local time. Intermediate stops were made at Bangkok and Rangoon before arriving at Calcutta. The flight took off from runway 19L at 15:29 and was cleared to climb under Visual Flight Rules and report when passing 7500 feet. The aircraft encountered a severe squall with thunderstorm shortly after takeoff when climbing to its cruising altitude, and suffered structural failure in the air which caused fire. The pilots lost control and the Comet crashed. PROBABLE CAUSE: “Structural failure of the airframe during flight through a thunder squall. In the opinion of the Court, the structural failure was due to overstressing which resulted from either:- (1) Severe gusts encountered in the thunder squall, or (2) Overcontrolling or loss of control by the pilot when flying through the thunderstorm.”