Air India Flight 855
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|Date||1 January 1978|
|Summary||Instrument malfunction, spatial disorientation|
|Site||Arabian Sea, near Mumbai, India|
|Aircraft type||Boeing 747-237B|
|Aircraft name||Emperor Ashoka|
|Flight origin||Sahar International Airport
|Destination||Dubai International Airport
Dubai, United Arab Emirates
Air India Flight 855 was a scheduled passenger flight that crashed during the evening of New Year's Day 1978 about 3 km (1.9 mi) off the coast of Bandra, Mumbai. All 213 passengers and crew on board were killed. The crash is believed to have been caused by the captain having become spatially disoriented after the failure of one of the flight instruments in the cockpit. It was the deadliest aviation accident in India until the Charkhi Dadri mid-air collision in 1996, and is still the second-deadliest behind the latter accident.
Sequence of events
Approximately one minute after takeoff from runway 27, Captain M.L. Kukar made a scheduled right turn upon crossing the Bombay coastline over the Arabian Sea, after which the aircraft briefly returned to a normal level position. Soon it began rolling to the left, and never regained level flight.
The cockpit voice recorder recovered from the wreckage revealed the captain made a verbal comment about his Attitude indicator (AI) having "toppled", meaning that it was still showing the aircraft in a right bank. The first officer, whose presumably functional AI was now showing a left bank, said that his AI was also toppled, but there is some belief that the Captain mistakenly took this to mean that both primary AIs were indicating a right bank. It was after sunset and the aircraft was flying over a dark Arabian Sea, leaving the aircrew unable to visually cross-check their AI instrument readings with the actual horizon outside the cockpit windows.
The Boeing 747 had a third backup AI in the center instrument panel between the two pilots, and the transcripts of the cockpit conversation show that the flight engineer may have been attempting to direct the captain's attention to that third AI, or perhaps to another instrument called the turn and bank indicator, just five seconds before the aircraft impacted the sea.
The captain's mistaken perception of the aircraft's attitude resulted in his using the aircraft flight control system to add more left bank and left rudder, causing the Boeing 747 to rapidly lose altitude. Just 101 seconds after leaving the runway the jet hit the Arabian Sea at an estimated 35-degree nose-down angle. There were no survivors among the 190 passengers and 23 crew members.
The partially recovered wreckage revealed no evidence of explosion, fire, or any electrical or mechanical failure; and an initial theory of sabotage was ruled out.
The investigation concluded that the probable cause was "due to the irrational control inputs by the captain following complete unawareness of the attitude as his AI had malfunctioned. The crew failed to gain control based on the other flight instruments."
US Federal District Judge James M. Fitzgerald, in a 139-page decision issued 1 November 1985, rejected charges of negligence against the Boeing Company, Lear Siegler Inc, and the Collins Division of Rockwell International Corporation in a suit related to the crash.
- Spatial disorientation
- Sensory illusions in aviation
- John F. Kennedy, Jr., plane crash
- Other aircraft that crashed shortly after takeoff, while turning above a dark ocean:
- Other aircraft that crashed due to instrument malfunction:
- Langewiesche, William (1998). "Chapter Four: On A Bombay Night". Inside the Sky: A Meditation on Flight. USA: Pantheon Books. ISBN 0-679-42983-2.
- Design Induced Errors, which includes a discussion of the crash.
- Pre-crash photos of 747 VT-EBD at airliners.net