The preliminary report by India’s Aircraft Accident Investigation Bureau (AAIB) into the Air India flight AI171 crash which crashed shortly after takeoff from Ahmedabad’s Sardar Vallabhbhai Patel International Airport on June 12 killing 270 people revealed that the fuel cutoff switches were moved from ‘run’ to ‘cutoff’ within a second of each other.
After the switches of both engines flipped, the Boeing 787 Dreamliner immediately shut down mid-air just seconds after take-off and began to lose thrust and sink down, according to the report.
“The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off,” the 15-page report said.
The pilots attempted to restart the engines by moving the fuel control switches back to the ‘run’ position. The Engine 1 started to recover, but Engine 2 was unable to arrest core speed deceleration despite repeated attempts to reintroduce fuel and increase core speed acceleration.
According to the report, “the aircraft achieved the maximum recorded airspeed of 180 knots IAS at about 08:08:42 UTC, and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from ‘RUN’ to ‘CUTOFF’ position one after another with a time gap of one second. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off.”
The report also revealed that just seconds before the aircraft lost power and went down near Ahmedabad airport, one pilot asked the other why he had cut off fuel to the engines, the second pilot reportedly denied, saying, “did not do so.”
“In the cockpit voice recording, one of the pilots is heard asking the other why he cut off. The other pilot responded that he did not do so,” the preliminary report on the Air India crash said.
“The EAFR recording stopped at 08:09:11 UTC At about 08:09:05 UTC, one of the pilots transmitted “Mayday Mayday Mayday ”. The ATCO enquired about the call sign. Air Traffic Controller (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 firefighting. They were joined by fire and rescue services of Local Administration,” the report said.
The aircraft was equipped with two Enhanced Airborne Flight Recorders (EAFR) that recorded a combined data stream of digital flight data and cockpit voice information. The downloaded flight data contained approximately 49 hours of flight data and 6 flights, including the event flight.
The investigation is ongoing, and the AAIB will continue to analyze the data to determine the cause of the deadly crash.
