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Decoding Preliminary Report Accident involving Air India’s B787-8 aircraft bearing registration VT-ANB

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Published on: 20 Jul 2025
Decoding Preliminary Report Accident involving Air India’s B787-8 aircraft bearing registration VT-ANB

Ahmedabad, July 2025 – On the afternoon of 12 June 2025, Air India Flight AI171, a Boeing 787‑8 Dreamliner registered VT‑ANB, embarked on its scheduled flight from Ahmedabad to London Gatwick. Less than two minutes after takeoff, the aircraft tragically collided with ground structures north of the airport, resulting in complete loss of life on board and extensive damage to property. The Aircraft Accident Investigation Bureau (AAIB) of India has now released its preliminary investigation report, presenting alarming technical findings and signaling a complex path ahead for investigators, manufacturers, and regulatory bodies globally.

In this detailed article, we decode every segment of the AAIB’s preliminary findings, enrich them with contextual explanations, aviation expertise, and historical insight, and present what this catastrophe means for Air India, Boeing, and the future of aviation safety.

1. Aircraft & Flight Basics: Who, What, Where, When

Aircraft Type & Registration

  • Boeing 787‑8 Dreamliner, registration VT‑ANB
  • Manufactured in 2013, with 41,868 flight hours

Flight Route

  • Departed: Sardar Vallabhbhai Patel International Airport (VAAH)
  • Destination: London Gatwick Airport (EGKK)
  • Departure: 13:37 IST, crash at 13:39 IST

Occupants

  • 230 passengers
  • 10 cabin crew
  • 2 flight crew

2. Fatalities, Injuries & Ground Damage

Human Toll

  • 241 fatalities onboard
  • 19 fatalities on the ground
  • 67 serious injuries on the ground

Property Damage

  • Five buildings impacted near BJ Medical College
  • Extensive fire and structural collapse

3. Air India & Manufacturer Response

Notification & Collaboration

  • AAIB, DGCA, and Air India alerted
  • NTSB (USA), AAIB (UK), TSB (Canada), and GPIAAF (Portugal) notified
  • Teams from Boeing, GE, and FAA dispatched

Appointed Investigators

  • Sanjay Kumar Singh – Investigator-in-Charge
  • Jasbir Singh Larhga – Chief Investigator
  • Additional SMEs included flight recorder analysts, aviation psychologists, engineers

4. Aircraft & Engine History

Airframe

  • Boeing 787-8, serial number 36279
  • Maintained under Air India’s maintenance program
  • Four non-critical Category C MELs, one Category A MEL

Engines

  • LH Engine (installed May 2025), RH Engine (installed March 2025)
  • Both passed airworthiness and maintenance checks

Fuel Control Advisory

  • FAA SAIB NM‑18‑33 issued in 2018 regarding fuel switch locking
  • Advisory not implemented—not mandatory
  • Switch replacements in 2019 & 2023 were unrelated to fuel switch malfunction

5. Meteorological & Aerodrome Snapshot

Weather at Departure

Time (IST)WindVisibilityCloudsTempQNH
13:00240°/06 kt6,000 mNSC36°C1001
13:30250°/07 kt6,000 mNSC37°C1001

Aerodrome Info

  • Runway 23: ILS Cat-I, 3505m x 45m
  • Airport ARFF: Category 9

6. Sequence of Events: Chronology of a Disaster

  • 11:17 IST: VT-ANB lands from Delhi (AI423)
  • 12:10 IST: Released for flight after minor issue fixed
  • 13:25 IST: Taxi clearance received
  • 13:37 IST: Cleared for takeoff
  • 13:38:33 IST: Crosses V1 speed (153 Kts)
  • 13:38:39 IST: Liftoff detected
  • 13:38:42 IST: Both engines shut down via fuel cutoff
  • 13:38:47 IST: Ram Air Turbine (RAT) deploys
  • 13:39:05 IST: Aircraft crashes
  • 13:44:44 IST: Fire & Rescue deployed

7. Critical Findings from Flight Recorders

EAFR & CVR Analysis

  • Aft EAFR damaged, Forward EAFR recovered & data downloaded
  • Audio captured cockpit exchange:
    • “Why did you cutoff?” — “I did not do so.”

Engine Shutdown & RAT Deployment

  • Engines shut off within 1 second
  • RAT deployed, providing emergency hydraulic power
  • Engine 1 relit briefly; Engine 2 failed to recover

8. Impact & Wreckage Distribution

Wreckage Trail

  • Initial tree impact, followed by hostel building collision
  • Debris field: 1000 x 400 ft
  • Nose gear found 307 ft southwest
  • Fuselage burned across Buildings A–F

Key Findings

  • Flap lever at 5°, consistent with takeoff config
  • Landing gear in “DOWN” position
  • Thrust levers at idle due to impact; data showed takeoff thrust

9. The Human Element: Crew Profiles

Captain

  • 56 y/o male, ATPL holder, 15,638 hours (8,596 on 787)

First Officer

  • 32 y/o male, CPL holder, 3,403 hours (1,128 on 787)

Both pilots:

  • Well-rested, medically cleared, passed preflight screening

10. Communications & ATC Exchange

Time (IST)Event
13:13:00Requested pushback/startup
13:25:15Taxi clearance granted
13:37:33Takeoff clearance issued
13:39:05“MAYDAY” call made
13:44:44Fire services deployed

11. Investigative Steps Taken

  • Wreckage secured and photographed
  • Engines quarantined in hangar
  • Fuel samples tested: No anomalies
  • Witness interviews and survivor statements recorded
  • Post-mortem analysis ongoing for crew and passengers

12. Early Technical Insights & Expert Interpretations

  • Both engines’ fuel switches moved to CUTOFF
  • SAIB advisory (switch locking design flaw) under scrutiny
  • FADEC behavior monitored during relight attempts
  • RAT confirms total power loss scenario

13. Human Factors, Crew Response & SOP Compliance

  • No clear pilot intent for fuel cutoff
  • SOP followed for relight sequence
  • Time window too short for engine recovery
  • No incapacitation or behavioral failure suspected

14. Preliminary Conclusions & Safety Recommendations

  • Dual engine shutdown: Extremely rare and dangerous
  • No immediate airworthiness directive issued
  • SAIB advisory likely to be revisited
  • Investigators exploring mechanical-electrical failure link

15. Contextualizing the Incident in Aviation Safety

  • Reminiscent of:
    • Asiana 214 (autothrottle)
    • Air France 447 (instrument failure)
    • Kegworth 1989 (fuel switch error)
  • Regulators may issue mandatory design fixes

16. What’s Next: Timeline & Expectations

  • Metallurgical and electronic testing continues
  • Cockpit transcript analysis
  • Safety recommendations by mid-2026
  • Airlines and OEMs expected to respond with fleet checks

17. Reflections: Balancing Technical Rigor with Emotional Resonance

This tragedy underscores:

  • The complexity of automated systems
  • The importance of hardware fail-safes
  • The need for international collaboration

We remember every life lost—and pursue answers so it never happens again.

Final Thoughts: Safety Through Transparency

This accident reminds us: aviation safety is a shared responsibility. With rigorous investigation, international cooperation, and swift implementation of safety measures, the legacy of AI171 can lead to stronger, safer skies.

*For official updates, follow [AAIB India]

India | Gujarat | Ahmedabad
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Ragavendran Ramesh
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Quick Info

What happened to Air India flight AI171 on June 12, 2025?
Air India flight AI171, a Boeing 787-8 aircraft registered VT-ANB, crashed shortly after takeoff from Sardar Vallabhbhai Patel International Airport in Ahmedabad while en route to London Gatwick. The aircraft lost altitude during initial climb and impacted buildings near the airport, resulting in a total loss of the aircraft and multiple fatalities.
How many people were on board Air India flight AI171?
There were 242 individuals on board: 230 passengers, 10 cabin crew members, and 2 flight crew members. Tragically, all but one passenger suffered fatal injuries in the crash.
What was the extent of injuries in the AI171 crash?
Out of the 242 individuals onboard, 241 suffered fatal injuries. One passenger sustained serious injuries. Additionally, 19 people on the ground also lost their lives.
Where did the Air India B787-8 crash occur?
The crash occurred in Ahmedabad, Gujarat, approximately 0.9 nautical miles from the departure end of Runway 23 at Sardar Vallabhbhai Patel International Airport. The aircraft struck the BJ Medical College hostel and other nearby buildings.
What caused the crash of Air India’s B787-8 aircraft?
According to preliminary data, the aircraft lost engine thrust shortly after takeoff due to both fuel control switches transitioning from RUN to CUTOFF. The engines shut down, leading to a rapid loss of altitude. Though the switches were returned to RUN and the engines attempted relight, it was too late to recover.
What is known about the fuel control switch issue in this accident?
The FAA had issued an advisory (SAIB No. NM-18-33) in 2018 regarding potential disengagement of fuel control switch locking mechanisms. This design was also present in the B787-8 involved. However, Air India had not conducted inspections since the SAIB was advisory and not mandatory.
Was there a mechanical failure reported on the flight before the crash?
Yes, a ‘STAB POS XDCR’ status message was reported by the previous crew. It was addressed by maintenance and the aircraft was cleared for flight. There were also several MEL items active at the time, though none directly indicated imminent engine failure.
What is a Minimum Equipment List (MEL) and how did it relate to this accident?
MELs allow an aircraft to operate with certain non-critical equipment inoperative under specified conditions. VT-ANB had several MEL items active, including one Category A MEL related to nitrogen generation performance, but all were within allowed validity and not directly linked to the crash.
What was the flight path of AI171 after takeoff?
The aircraft took off from Runway 23 and initially climbed before losing thrust. It then descended and impacted several buildings, including the BJ Medical College hostel, scattering debris over a large area.
What is the role of the Ram Air Turbine (RAT) observed during the crash?
The RAT deploys automatically to provide emergency hydraulic and electrical power when both engines fail. CCTV footage confirmed its deployment, indicating a total loss of engine power during flight.
Did both pilots survive the crash?
No, both the captain and the co-pilot suffered fatal injuries in the accident.
What were the pilot’s qualifications and experience?
The captain held an ATPL with over 15,000 flying hours, including over 8,200 hours on the B787. The co-pilot held a CPL with over 3,400 hours, including over 1,100 hours on the B787.
Were the flight recorders recovered after the crash?
Yes, both the forward and aft Enhanced Airborne Flight Recorders (EAFR) were recovered. The forward EAFR was successfully downloaded and contained valuable flight and voice data from the accident flight.
What did the Cockpit Voice Recorder (CVR) reveal about the crash?
The CVR captured one pilot asking the other why the fuel control switches were cut off, with the other denying they did it. This indicates the cut-off might have occurred unintentionally or due to system malfunction.
Were there any indications of external interference like bird strike or sabotage?
No, CCTV footage and other preliminary findings show no significant bird activity or evidence of external interference. The crash appears to be linked to internal technical or operational issues.

In-Depth Answers

How many buildings were affected by the crash of AI171?
Five buildings in the vicinity of the BJ Medical College were impacted, suffering major structural and fire damage due to the aircraft's impact and debris field.
What is the status of the accident investigation?
The investigation is ongoing. Initial analysis of flight data and cockpit voice recordings has been completed, and further examinations, witness statements, and testing are underway to determine the root cause.
Who is leading the investigation into the AI171 crash?
The Aircraft Accident Investigation Bureau (AAIB) of India is leading the investigation. International support has been provided by NTSB (USA), Boeing, GE, FAA, and other state agencies with affected citizens.
Was the aircraft within weight and balance limits at takeoff?
Yes, the aircraft’s takeoff weight was 213,401 kg, which was within the maximum allowable takeoff weight of 218,183 kg.
What were the weather conditions at the time of the accident?
The weather was reported as clear with a visibility of 6000 meters, no significant clouds, temperature around 37°C, and light winds from the west. Conditions were not a contributing factor to the accident.
What were the final moments recorded on the EAFR?
Data shows both engines shut down shortly after takeoff, with the crew attempting a relight sequence. Engine 1 began recovering, but Engine 2 could not stabilize. A MAYDAY call was made shortly before impact, and the EAFR stopped recording at 08:09:11 UTC.
What is the significance of the flap and thrust lever positions during the crash?
The flap lever was in a normal takeoff setting, and thrust levers were originally in takeoff position. However, upon impact, they were found near idle, likely due to damage. The EAFR confirmed they remained at takeoff thrust until fuel cutoff.
Were there any indications of pilot error in the preliminary report?
The report does not attribute the accident to pilot error. However, it notes an unexplained fuel cutoff and a cockpit conversation indicating neither pilot intentionally moved the switches, leaving room for further technical investigation.
Did the Emergency Locator Transmitter (ELT) activate during the crash?
No, the ELT did not activate during the crash event, although it typically should in a crash scenario. The reason for this is not clarified in the preliminary report.
What is a ‘Golden Chassis’ and why was it used in this investigation?
A ‘Golden Chassis’ is an identical recorder housing used to download data from a damaged EAFR. It was sourced from the NTSB and used successfully to retrieve flight data from the forward EAFR in this investigation.
Was the Air India aircraft airworthy at the time of departure?
Yes, the aircraft held a valid Certificate of Airworthiness and all applicable Airworthiness Directives and Service Bulletins were complied with. Maintenance records indicated it was airworthy at the time of departure.
Were there any prior issues with the aircraft’s fuel control switch?
The fuel control module had been replaced in 2019 and 2023, but there were no reports of defects related to the fuel control switch on VT-ANB since then.
What is the next major maintenance check due on this aircraft?
The next major scheduled maintenance, a D Check, was due in December 2025. The last line maintenance checks (L1-1 and L1-2) were completed earlier and were within schedule.
What is the function of the APU in an aircraft like the Boeing 787-8?
The Auxiliary Power Unit (APU) provides power to start the engines and supplies electrical and pneumatic power when the main engines are off. During the AI171 accident, the APU air inlet door was observed to begin opening, indicating automatic APU start following engine shutdown.
How did the investigators confirm the aircraft had taken off?
The EAFR data confirmed that the aircraft transitioned to air mode at 08:08:39 UTC, consistent with liftoff. The flap handle position was also consistent with a normal takeoff setting.
What are FADEC systems and how did they react in this incident?
FADEC (Full Authority Digital Engine Control) systems manage engine performance automatically. Upon the fuel switches returning to RUN, FADEC initiated relight and thrust recovery, successfully restarting Engine 1 but failing to stabilize Engine 2.
What were the calculated V-speeds for AI171 during takeoff?
The V-speeds for AI171 were V1 at 153 knots, Vr at 155 knots, and V2 at 162 knots. These speeds were achieved before the engine shutdown occurred.
Why is the flap setting important in aircraft accidents?
Flap settings affect lift and takeoff performance. The flap was found in the 5-degree position during the AI171 crash, confirming a normal configuration for takeoff.
What was the attitude of the aircraft at the time of first impact?
The aircraft had a nose-up attitude of about 8 degrees and wings level when it initially struck Building A, as indicated by impact marks and debris layout.
What was the significance of the throttle quadrant position post-crash?
Though the quadrant was found damaged and the levers near idle, EAFR data showed they remained in takeoff thrust position until the engines shut down, suggesting no manual throttle rollback occurred.
How far did debris from the crash spread from the initial impact point?
The wreckage was distributed over an area approximately 1000 feet by 400 feet, with the farthest debris located about 765 feet southwest of the initial impact.
What were the states of the engines post-impact?
Both engines separated during the crash. Engine 1 was found near Building D with fire damage, while Engine 2 was near Building A under a water tank. Engine 1 showed signs of successful relight.
How was the RAT deployment observed in the AI171 crash?
The Ram Air Turbine deployment was captured on airport CCTV footage. Its activation confirmed loss of main power sources, prompting RAT deployment for emergency hydraulics.
Was dangerous cargo aboard the AI171 flight?
No, there were no dangerous goods on board according to the flight’s manifest and safety documentation.
What is the significance of the 'STAB POS XDCR' fault noted before the flight?
This fault relates to the stabilizer position sensor. Although reported by the previous crew and addressed before flight, it is not indicated as contributing to the crash at this stage of the investigation.
Why were foreign agencies involved in this investigation?
Foreign agencies including NTSB (USA), TSB (Canada), and others were involved because the aircraft and engines were manufactured in the USA, and victims included citizens from several countries.
How did the flight crew perform the day of the accident?
Both pilots had adequate rest and passed breath analyzer tests before the flight. The captain acted as Pilot Monitoring and the co-pilot was Pilot Flying during the accident flight.
What is the ‘Golden Chassis’ method used for data recovery?
It involves placing the data module from a damaged recorder into a functional identical unit (Golden Chassis) to access and download flight data, which was done successfully in this case.
What kind of engine was installed on the B787-8 aircraft VT-ANB?
The aircraft had GE GEnx-1B70 series engines installed—Engine 1 (LH) was installed in May 2025, and Engine 2 (RH) in March 2025, both relatively recent installations before the accident.
Were there any signs of structural failure before impact?
The preliminary report does not mention in-flight structural failure. All damage appears consistent with the impact forces during descent and ground collision.
Did the pilots attempt to restart the engines after failure?
Yes, both fuel control switches were moved back to the RUN position, triggering FADEC relight attempts. Engine 1 began recovering, but Engine 2 could not sustain recovery.
How did the crash affect local infrastructure in Ahmedabad?
Several buildings including a medical college hostel suffered major structural and fire damage. The crash impacted both the aviation community and local civilian population.
What was the last communication between the aircraft and ATC?
At 08:09:05 UTC, the crew transmitted a 'MAYDAY MAYDAY MAYDAY' call. ATC attempted to confirm the call sign but received no response before observing the crash.
What maintenance was due next on the aircraft?
The aircraft was scheduled for a major D Check in December 2025. All routine maintenance checks were up to date at the time of the crash.
Were the aircraft’s flight data and voice recorders damaged?
Yes, both EAFRs sustained impact and thermal damage. However, the forward EAFR was successfully accessed using the Golden Chassis, while the aft recorder was too damaged for standard recovery.
Were any postmortem reports used in the investigation?
Yes, postmortem reports of crew and passengers are being analyzed to support medical and psychological evaluations relevant to the investigation.
Was pilot incapacitation considered a factor in this crash?
At this stage, the preliminary report does not confirm any pilot incapacitation. Medical tests and CVR analysis are still being reviewed as part of the broader investigation.
What is the current status of the accident investigation?
The investigation is ongoing. Site work is complete, components and engines are quarantined, and detailed data analysis is underway to determine the root causes of the crash.

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