|Date||16 August 1991|
|Summary||Controlled flight into terrain|
|Site||Thangjing Hill, Manipur, India |
|Aircraft type||Boeing 737-2A8|
|Flight origin||Calcutta airport, Calcutta|
|1st stopover||Imphal Municipal Airport,|
|Destination||Dimapur Airport, Dimapur, Nagaland|
Indian Airlines Flight 257 was an Indian Airlines flight operating on the Kolkata–Imphal–Dimapur route. On 16 August 1991 at 12:46 Indian Standard Time (UTC+7), the Boeing 737-2A8 registered VT-EFL crashed on its descent into Imphal, Manipur, India, killing all 63 passengers and 6 crew members on board.
The flight, operating on the Calcutta–Imphal–Dimapur route, crashed into Thangjing Hill, about 37 kilometres (23 mi; 20 nmi) south-west of the Imphal Airport. The aircraft had started the short flight from Calcutta around 12:00 pm and it began a descent into Imphal Airport at around 12:41 pm. Visibility at that time was 7 kilometres (4.3 mi; 3.8 nmi). Imphal Airport lost contact with the aircraft just after 12:45, at 1,500 metres (4,900 ft) altitude on the Instrument Landing System. The search and rescue efforts were hampered by bad weather conditions and a hilly and slushy terrain.
There were 69 people on board, of which 63 were revenue passengers (68 adults and 1 infant). Of the 63 passengers inclusive of one child on board, 31 passengers with the child were booked for Imphal, Manipur and 31 were booked for Dimapur, Nagaland.
There were 6 crew members. The flight was piloted by Captain Sekhar Flaldar and Co-pilot Roy Choudhury.
The probable cause of the crash 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 10,000 feet (3,000 m) 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".