What happened
During a night operation at Calcutta-Dum Dum Airport, a C-47 cargo flight was cleared to line up on runway 01L for a scheduled transport to Pasighat. Shortly after receiving permission to enter the runway, the aircraft was involved in a collision with an Airwork Handley Page H.P.81 Hermes IV/A that was in the process of landing on the same strip. The impact resulted in the total destruction of the C-47, and all four crew members on board the cargo plane lost their lives. The Handley Page H.P.81 Hermes IV/A came to a halt a short distance from the wreckage but was subsequently declared a total loss due to damage. At the time of the incident, visibility at the airport was recorded at 2,000 yards.
Findings
Investigations into the accident determined that the collision was driven by pilot error during the landing sequence. The commander of the Hermes aircraft had turned down the radio communications during the final portion of a radar-assisted approach. Furthermore, the decision to proceed with the landing under visibility conditions that prevented the crew from clearly identifying the correct runway contributed to the collision.