The Aircraft Accident Investigation Bureau (AAIB) has issued its first report into the Air India Dreamliner crash at Ahmedabad on June 12.
As suspected, both engines of the Boeing 787-8 lost power mid-air barely a second after takeoff, resulting in the crash that killed everyone on board.
The initial investigation indicates that the fuel control switches of the aircraft, which provide fuel supply to the engines, were switch OFF in quick succession, one after the other, within a second. The fuel cutoff resulted in both the engines shutting down, leading to a critical loss of thrust.
Cockpit voice recordings heard a heated dialogue between the pilots. One is heard saying, "Why did you cut off?" The other pilot responds by saying, "I didn't."
The CUTOFF transition is most likely to be at the center of the current investigation, considering its direct involvement in starving the engines of fuel, according to investigators.
The report, released early yesterday morning, contains proof from CCTV footage in the airport that the Ram Air Turbine (RAT) deployed after taking off — an obvious indication that the plane had experienced total power loss.
"The CCTV footage recorded from the airport captured Ram Air Turbine (RAT) getting deployed during the initial climb after lift-off. There was no appreciable bird activity within proximity of the flight path. The aircraft began losing altitude before passing over the perimeter wall of the airport," the report added.
Black box information, accessed from the Enhanced Airborne Flight Recorder (EAFR), indicated that pilots tried to regain engine operation by moving both fuel switches to 'RUN'. Engine 1 worked, while Engine 2 remained in trouble.
"Engine 1's central deceleration ceased, reversed and began to make progress towards recovery. Engine 2 could relight but was unable to halt central speed deceleration and reintroduced fuel again and again in an attempt to boost central speed acceleration and recovery," the AAIB said.
The plane was in the air for a total of just 32 seconds and had covered only 0.9 nautical miles when it crashed into the BJ Medical College Hostel on the airport outskirts at 1:39 p.m., the report said.
Though the thrust levers were discovered close to idle at the crash scene, the flight data established that they did not move forward until impact. The fuel control switches were also in the 'RUN' position during the crash, which suggests that the two pilots were actively attempting to regain control.
Dispelling one of the hypotheses, the report verified that the flap setting was five degrees and the landing gear remained in the DOWN position — both typical for takeoff.
One of the report's most significant findings is the lack of any indicator of sabotage. The AAIB did, however, find a previous FAA advisory warning of a possible flaw in the locking mechanism of the fuel control switch.
"On December 17, 2018, the FAA released Special Airworthiness Information Bulletin (SAIB) No. NM-18-33 to address the possibility of disengagement of the fuel control switch locking feature. Operators of Model 737 airplanes reported to the FAA that the fuel control switches were being installed with the locking feature in a disengaged position. The FAA did not regard the airworthiness issue as an unsafe condition that would necessitate airworthiness directive (AD)," the report declared.
Air India did not conduct inspections related to the bulletin, as it was advisory in nature and not mandated.
"According to Air India's information, the recommended inspections were not done since the SAIB was advisory and not compulsory. During the checking of the maintenance records, the throttle control module has been replaced on VT-ANB in 2019 and 2023. The replacement was not due to the reason of the fuel control switch. No defect has been reported regarding the fuel control switch since 2023 on VT-ANB," the report further stated.
The AAIB excluded inclement weather as the cause. Skies were clear, visibility was excellent, and wind conditions were normal. Both pilots were rested, healthy, and properly certified and experienced to fly the plane.
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