Seconds before Air India flight 171 crashed while ascending from Ahmedabad, the fuel control switches of both its engines were cut off, a preliminary investigation report said on Saturday, suggesting a catastrophic pilot error in the cockpit of the Boeing 787 Dreamliner. The Airlines Pilots Association of India raised the issue with the report, saying the investigation is “shrouded in secrecy,” appears to be biased against the pilot and has come to a conclusion hastily.
Just 13 seconds before the Air Traffic Control received the “MAYDAY” call from the Ahmedabad-London Air India-171 Dreamliner on the day of the crash on June 12 that killed 260 people, the Aircraft Accident Investigation Bureau (AAIB) report has revealed that the Boeing 787-8 aircraft’s engine fuel control switches transitioned from ‘RUN’ ( fuel flowing) to ‘CUTOFF’ ( fuel stopped) position within a second of each other after take- off, leading to the worst Indian airlines aviation disaster in four decades.
In its 15-pages report released on Friday night, the AAIB also ruled out bird hit theory and said there was no immediate evidence of sabotage. The report also said there were no weather issues at the time of the crash. “The skies were clear, visibility was good, and winds were not too strong. Within seconds of takeoff, both engine fuel control switches were moved from “RUN” to “CUTOFF,” one after the other, with only a one-second gap.”
According to a chronology laid out in the report, both engine fuel cutoff switches “transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec” at 08:08:42 UTC, just as the aircraft reached its maximum speed of 180 knots during take-off. This immediately cut fuel supply to both engines, caused them to lose power. Importantly in the cockpit voice recording, one pilot could be be heard asking, “Why did you cut off?” and the other pilot replied, “I didn’t”. The report doesn’t specify which pilot made which statement. The report said that the additional cockpit voice recorder analysis may reveal more details about crew communications and other audio, such as any alarms going off.
The fact that the switches transitioned to ‘CUTOFF’, starving the engines of fuel, is expected to be the key focus area of the investigation going forward. The report, however, does not determine what caused the fuel switches to move - whether it was human action, mechanical failure, or electronic malfunction. The twin engine shutdown is currently unexplained.
That critical question remains unanswered and is the focus of the ongoing investigation.
The fuel cut-off switches, critical for regulating fuel supply, should not have shifted simultaneously under normal circumstances. The pilot flying was co-pilot Clive Kunder, while pilot-in-command Sumeet Sabharwal was pilot monitoring for this flight. Sabharwal had nearly 8,600 hours on the Boeing 787 under his belt, while Kunder had over 1,100 hours, both of which were more than sufficient. Both the pilots were also medically fit and rested and had adequate experience flying that type of aircraft.
Soon after both fuel cut-off switches moved from RUN to CUTOFF, one second apart, a Ram Air Turbine (RAT) pump was deployed to supply hydraulic power as both engines fell below minimum idle rate. About 10 seconds later, Engine 1 fuel cut-off switch moved to its so-called RUN position, followed by Engine 2 four seconds later. The pilots managed to relight both engines, but only Engine 1 recovered while Engine 2 failed to build up enough power again to reverse deceleration.
At about 08:09:05 UTC, one of the pilots transmitted “MAYDAY MAYDAY MAYDAY”. The air traffic control officer (ATCO) enquired about the call sign. The ATCO did not get any response but observed the aircraft crashing outside the airport boundary and activated the emergency response.
At 08:14:44 UTC, Crash Fire Tender left the airport premises for Rescue and fire fighting. They were joined by Fire and Rescue services of Local Administration.
At the time the aircraft took off, the co-pilot was flying the plane, while the captain was monitoring. The time between the takeoff and the crash was only about 30 seconds.
“The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC (13.38 IST) and immediately thereafter, the Engine 1 and Engine 2 fuel cut-off switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec,” the report said.
As per the report, the engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. “In the cockpit voice recording, one of the pilots is heard asking the other why did he cut-off. The other pilot responded that he did not do so,” it said.
Almost immediately after the plane lifted off the ground, the CCTV footage showed a backup energy source called ram air turbine (RAT) had deployed, indicating a loss of power from the engines.
The report provided only a limited picture of the interaction between the two pilots in the flight deck and also did not say how the switches could have flipped to the cut-off position during the flight.
Normally, flipping to cut-off, which almost immediately cuts fuel supply, is often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report did not indicate there was any emergency requiring an engine cut-off.
The recovery was ultimately impossible due to insufficient time and altitude. The aircraft was only about 625 feet above ground when the engines failed, and engine restart procedures require significantly more time than the 29 seconds available before impact. Modern jet engines can restart in flight, but typically need several minutes and higher altitudes to complete the process successfully.
The aircraft was airborne only for 32 seconds and the report notes that it travelled only 0.9 nautical miles before crashing into the BJ Medical College Hostel close to the airport
The report points to a series of possibilities and also raises multiple questions on what transpired inside the doomed flight. Putting to rest a key area of speculation, the report revealed that the flap setting (at five degrees) and the landing gear lever position (DOWN) were normal for take-off.
The investigating body noted that the Federal Aviation Authority had issued an advisory in 2018 about the fuel control switches. “The FAA issued Special Airworthiness Information Bulletin (SAIB) No. NM-18-33 on December 17, 2018, regarding the potential disengagement of the fuel control switch locking feature. This SAIB was issued based on reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The airworthiness concern was not considered an unsafe condition that would warrant airworthiness directive (AD) by the FAA,” the report said.
Crucially, the Air India did not carry out the suggested inspections because the bulletin was advisory rather than mandatory. The airline had replaced the aircraft’s throttle control module twice-in 2019 and 2023-but these replacements were unrelated to fuel switch issues.
The report does not currently assign blame or recommend changes for either Boeing, the manufacturer of the B787-8 aircraft, or General Electric, which makes the GE GEnx-1B engines used in the jet.
In a statement, the Air India said that it “stands in solidarity with the families and those affected” and “[continues] to mourn the loss” of those killed in the accident. Air India said it was “working closely with stakeholders, including regulators” and “continue to fully cooperate with the AAIB and other authorities as their investigation progresses.”
Investigation continues, key areas of focus