Air India #AI171 Crash: AAIB Preliminary Report..

In a major development in the investigation of the tragic crash of Air India Flight AI-171, India’s Aircraft Accident Investigation Bureau (AAIB) has released its preliminary report, identifying a critical mechanical failure and a sequence of cockpit events that led to the loss of 247 lives.

The #Boeing #b787dreamliner, registration VT-ANB, was operating a long-haul flight from #Ahmedabad to #London Gatwick when it crashed just 38 seconds after takeoff, plummeting into a residential and hospital area in Meghani Nagar.

🔍 Root Cause: Captain’s Seat Slipped During Rotation

According to the AAIB, the captain’s seat suddenly slid backward during rotation, a moment when the aircraft was lifting off the runway. This rearward movement was due to the failure of the AFT locking mechanism of the seat track.

As the captain's body was thrust rearward, his weight inadvertently pulled the thrust levers into idle, drastically reducing engine power during a critical phase of flight. The First Officer attempted to advance the throttles but was unable to counter the mechanical force and body weight obstructing the levers.

🧩 Mechanical Evidence & Maintenance Oversight

Wreckage inspection revealed fractured seat locking pins, specifically part number BACB30LN5S02, as the point of failure. Notably, maintenance logs confirm the seat had been serviced just 11 days prior to the crash for issues related to “stiff adjustment.”

However, investigators found no documentation of a post-repair functional test, which is a critical oversight in the aircraft's maintenance chain.

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📊 Flight Deck Timeline (From CVR & FDR)

+0:12 seconds: Rotation initiated

+0:15 seconds: Seat slides; thrust levers pulled back

+0:18 seconds: Captain exclaims “My seat!”

+0:26 seconds: Aircraft stalls at 214 feet AGL

+0:38 seconds: Aircraft impacts ground

The quick deterioration from a normal takeoff to total loss of lift occurred in under half a minute, highlighting the unforgiving nature of low-altitude flight anomalies.

🔥 Contributing Factors Identified

1. Extreme Ambient Temperature:
The takeoff was conducted at a recorded 43°C, reducing engine performance and leaving no margin for error.

2. Crew Coordination Failure:
During the emergency, no callouts for “Go-Around” or “Stabilizer Trim” were made, possibly due to confusion and distraction from the seat failure.

3. Design Vulnerability in Boeing 787:
The thrust levers lack a reverse torque safeguard or mechanical lock, which would otherwise prevent unintended movement due to external force.

⚠️ Immediate Global Safety Actions

In response to the findings:

FAA & EASA have issued an Emergency Airworthiness Directive (AD 2025-16-51), requiring all operators to inspect B787 captain seat tracks within 72 hours.

Air India has grounded 12 aircraft with similar seat maintenance records pending reinspection.

Boeing has committed to:

Redesigning the seat locking mechanism

Updating throttle lever resistance protocols for future fleet safety (expected Q3 2026)

🕯️ Human Toll and Survivor Update

The crash claimed the lives of 243 passengers and crew, in addition to 4 fatalities on the ground, including medical staff at the impacted hospital.

There is one known survivor, a 24-year-old female passenger, who remains in critical condition with extensive burns. She continues to receive intensive care.

📅 Next Steps

The final AAIB report with full engineering and human factors analysis is scheduled for July 30, 2025.

In August 2025, the ICAO will convene an international summit focused on cockpit ergonomics, design vulnerabilities, and flight crew safety systems.

✈️ Conclusion

The AI-171 tragedy underscores how a small mechanical failure—if overlooked—can cascade into a catastrophic event, especially during critical flight phases. This accident is a somber reminder for the global aviation community of the importance of design resilience, maintenance accountability, and crew preparedness.

As investigations continue, the focus remains firmly on enforcing safety directives and implementing engineering reforms to prevent such tragedies in the future.

🔗 Sources:

AAIB Preliminary Report – AI171

FAA Emergency AD 2025-16-51

Boeing Service Bulletin .

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