Investigation Summary
The investigation revealed a series of deviations from Standard Operating Procedures (SOP). Despite reporting that they were commencing the DME ARC approach, the crew failed to turn and remained at 4,000 feet, well above the 2,000-foot requirement. By the time they reached the lead radial, they were at 3,000 feet and only 3.5 nautical miles from the airport, whereas they should have been at 2,000 feet and 11 nautical miles out. To lose altitude, the crew kept the engines at idle and performed a series of zig-zag maneuvers. Realizing they were still too high, Captain Sohanpal requested a 360-degree orbit. During this turn, the airspeed dropped to 119 knots, triggering the stick shaker. The crew's response was fatal: they retracted flaps from 40 to 15 degrees, which significantly reduced lift, and failed to lower the nose to recover from the stall. The aircraft struck trees and residential quarters, killing 50 occupants and 5 people on the ground.
Final Conclusions
The Board of Inquiry concluded the primary cause was human error. The crew failed to follow established approach procedures, resulting in a 'high and fast' situation. They compounded this by maintaining idle thrust until the aircraft reached a critical stall speed. The final error was the execution of a go-around procedure (retracting flaps and gear) rather than an approach-to-stall recovery procedure (reducing pitch and applying maximum thrust without changing configuration), which made the stall unrecoverable.
Video Analysis
Boeing 737 Crashes in India | Alliance Air 7412 — A detailed breakdown of the pilot errors and procedural deviations that led to the stall and crash of Alliance Air 7412 in Patna.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Pilot Not Flying (PNF) / Instructor. Seated in the right seat. Identified as Manjit Singh Sohanpal.
Captain
Pilot Flying (PF) / Captain in training. Seated in the left seat. Identified as Arvind Singh Bagga.
Systems & Failure Modes
Stick Shaker
A mechanical device that vibrates the control yoke to provide a tactile warning to the pilots of an impending stall.
GPWS
Ground Proximity Warning System, which issued a 'Pull Up' warning in the final seconds as the aircraft lost altitude.
DME ARC
A navigational procedure requiring the pilot to fly a curved track at a specific distance from a VOR/DME station.
Interesting Facts
- 01The aircraft was 20 years old and was nearing retirement due to upcoming Indian regulations on aircraft age.
- 02The aircraft's Manufacturer Serial Number (MSN) was 22280 and its Line Number was 671.
- 03The Captain in training was flying from the left seat, while the more senior Captain handled radio communications from the right seat.
- 04Five people on the ground were killed when the aircraft struck residential quarters No. 6 and 8.
- 05The Patna ILS glide slope was restricted to 300 feet due to tall trees in a nearby zoological garden that the local government refused to trim.
- 06The aircraft had previously been involved in a substantial wing-strike accident in 1986 but was repaired and returned to service.
Safety Actions & Advisories
Pilot Training Enhancement
Alliance Air was directed to emphasize crew resource management (CRM), adherence to SOPs, and specific training for recovery from both 'approach to stall' and 'clean stall' conditions.
Obstacle Removal
The Board of Inquiry recommended that the Ministry of Civil Aviation and the Government of Bihar remove or trim the tall trees in the zoological garden that interfered with the ILS glide path.