257
1991-AUG-16 · Thangjing Hill, Manipur, India

Indian Airlines — Flight 257

Indian Airlines Flight 257 crashed into Thangjing Hill during its approach to Imphal after the flight crew deviated from the established flight plan and instrument approach procedures. The captain, who was highly familiar with the route, relied on visual landmarks and instinct rather than instrument data in overcast conditions, leading to a premature descent into hilly terrain. All 69 people on board were killed.

Aircraft
Boeing 737-2A8 Adv
Registration
VT-EFL
Phase
Approach
Cause
Controlled Flight Into Terrain (CFIT)
Souls on Board
69
Fatalities
69
Origin → Dest
Netaji Subhash Chandra Bose International Airport, Calcutta, India → Imphal Airport, Manipur, India
Report
Final

Investigation Summary

The investigation revealed a significant breakdown in standard operating procedures and Cockpit Resource Management (CRM). Captain Sekhar Haldar, who had flown the Calcutta to Imphal route at least 36 times, developed a sense of over-confidence that led him to bypass mandatory waypoints. Instead of flying over Agartala as reported to Air Traffic Control, the crew took a shortcut, providing false position reports to the tower. This deviation caused a loss of accurate time and distance references. During the approach, the crew commenced a procedural turn and descent to 5,000 feet without confirming they were overhead the VOR. The co-pilot, Captain Roy Choudhury, failed to challenge these deviations, acting as a passive observer while the aircraft was flown into a mountain 300 feet below its peak.

Final Conclusions

The Board of Inquiry concluded the accident was caused by a grave error by the Pilot-in-Command, who failed to adhere to the operational flight plan and ILS let-down charts. His decision to descend early and turn for the outbound leg without reporting over the VOR resulted in a loss of situational awareness in hilly terrain. This behavior was attributed to extreme familiarity with the area, leading to a reliance on visual cues that were obscured by 8-okta cloud cover.

Video Analysis

No video analysis linked for this case file yet.

Airframe & Maintenance

Airframe Hours
29,729
Cycles
33,574
Engines
Pratt & Whitney JT8D-17A

Crew Experience

Captain

Total hours
3,783
On type
2,369

Captain Sekhar Haldar (37). Pilot Flying.

First Officer

Total hours
1,647
On type
1,397

Captain D. B. Roy Choudhury (26). Pilot Not Flying.

Systems & Failure Modes

i

VOR (VHF Omnidirectional Range)

The crew failed to accurately report their position relative to the Imphal VOR before commencing their descent.

i

ILS (Instrument Landing System)

The aircraft was on an ILS approach but failed to follow the prescribed let-down chart.

i

CVR (Cockpit Voice Recorder)

Captured the captain's reliance on visual landmarks and the co-pilot's lack of corrective action.

Interesting Facts

  • 01The aircraft struck Thangjing Hill at an altitude of 6,700 feet, just 300 feet below the summit.
  • 02The crew provided false position reports to ATC, claiming to be over Agartala when they were actually on a shortcut heading.
  • 03Weather at the time of the accident was overcast (8 okta), severely limiting visibility.
  • 04The Flight Data Recorder only captured five parameters: altitude, heading, airspeed, vertical acceleration, and time; however, vertical acceleration data was only available for the takeoff phase.
  • 05The crash site was located approximately 37 kilometers south-west of Imphal Airport.

Safety Actions & Advisories

Independent Investigative Body

The Board of Inquiry recommended the establishment of an independent body for transport accident investigations in India.

Flight Crew Discipline

Issued 50 recommendations focused on improving flight crew training, discipline, and adherence to operational flight plans.

Location

Thangjing Hill, Manipur, India · 24.8200, 93.9500

Case File History

  1. New evidenceUpdated event timeline and findings.

Related Cases

Case ID · indian-airlines-257-1991Last updated · Filed

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