Investigation Summary
Shortly after departure, the Captain's Attitude Director Indicator (ADI) malfunctioned, freezing in a slight left bank. While the aircraft was actually leveling off, the Captain believed he was still banking left and initiated a right-wing-down correction. However, he then perceived the aircraft was banking too far right and reversed the input, entering a steep left bank. Because it was night and over the sea, there was no visible horizon. The First Officer's ADI was functioning correctly and showed the extreme bank, but a breakdown in Cockpit Resource Management (CRM) and spatial disorientation led the crew to follow the failed instrument until the aircraft struck the water in a nose-down, 108-degree left bank.
Final Conclusions
The crash was caused by the Captain's failure to cross-check his malfunctioning ADI with other available instruments (the First Officer's ADI and the standby horizon) and the crew's inability to resolve the conflicting information, resulting in spatial disorientation and a loss of control.
Video Analysis
The Crash That Shocked Mumbai on New Year's Day | Air India 855 — An analysis of how a single instrument failure and spatial disorientation led to the loss of the 'Emperor Ashoka' Boeing 747.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Attitude Director Indicator (ADI)
The primary instrument showing the aircraft's pitch and roll; the Captain's unit failed due to a seized gimbal.
Standby Horizon
A third, independent attitude indicator located in the center of the instrument panel which the crew failed to consult.
Comparator Warning System
A system designed to alert pilots when their primary instruments disagree, which was present but did not prevent the crash.
Interesting Facts
- 01The aircraft was Air India's first Boeing 747, named 'Emperor Ashoka'.
- 02The accident occurred in total darkness over the ocean, providing no external visual references.
- 03The Captain had over 18,000 flight hours, yet succumbed to spatial disorientation.
- 04All 213 people on board were killed instantly upon impact.
- 05The wreckage was located in approximately 30 feet of water.
Safety Actions & Advisories
CRM Training Emphasis
The accident highlighted the need for improved Cockpit Resource Management, specifically regarding how junior officers should challenge senior captains during instrument discrepancies.
Instrument Cross-Check Procedures
Aviation authorities reinforced the importance of the 'rule of three'—comparing two primary instruments against a standby instrument to identify a failure.