Indian Airlines Flight 257 was a flight on August 16, 1991 that crashed on its descent into Imphal, killing all 69 occupants (including 1 infant).
The flight was operating on the Calcutta-Imphal sector crashed into Thangjing hills, about south-west of the Imphal airport. The aircraft had earlier taken off from Calcutta around noon and it began a descent into Imphal airport at around 12:41, with the visibility at that time being seven kilometers. However, the aircraft lost contact with Imphal airport after 12:45 or 5000 feet on the Instrument Landing System. The search and rescue efforts were hampered by bad weather conditions and a difficult (slushy) terrain.
The probable cause of accident was attributed to an "error on the part of the Pilot-in-Command in not adhering to the operational flight plan and ILS let down chart and not realizing that his early descent to and turning right for outbound leg without reporting overhead VOR would result in loss of time reference and as such misplace him in the hilly terrain. The Pilot-in-Command's action may have been influenced by his extreme familiarity with the terrain". Indian Airlines paid a compensation of Rs. 5 lakhs for each adult deceased passenger and Rs. 2.50 lakhs for the deceased infant in the accident.