‘Fuel to Air India plane was cut off before crash’

Why did he cutoff?, the pilot asked.

I did not do so, the other responded.

This is the chilling exchange between the two pilots captured in the cockpit voice recording moments before Air India’s Flight 171 went down causing one of the worst air crashes in recent memory. Exactly a month after the crash, where 260 people were killed, a preliminary report based on the assessment of the cockpit voice recorder and the flight data recorder, narrows the focus on the aircraft’s fuel control switches while raising questions about one of the pilot’s actions.

The preliminary report, prepared by India’s Aircraft Accident Investigation Bureau (AAIB) finds that both of the London-bound Boeing 787 Dreamliner’s fuel control switches were abruptly moved from the ‘run’ to the ‘cut off’ position shortly after takeoff, starving the engines of fuel and triggering a total power loss.

Usually, the switches are moved to the ‘cut off’ position to turn off the engines upon landing. They are also designed with a locking mechanism to prevent any accidental activation. To turn a switch to either ‘run’ or ‘cut off’, one has to pull it outward, and then move it to the desired position, where, upon release, it settles into that locked position. There are also protective guard brackets to shield the switches from any accidental bumps.

According to the report, the two fuel control switches were turned off “one after another” about a second apart, and “the aircraft started to lose altitude before crossing the airport perimeter wall.” “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 report says.

This is when one of the pilots is heard in the cockpit voice recording asking the other why he had cut the fuel off, to which the other responds saying he hadn’t done so.

The fuel switches were then moved back into their normal inflight position, automatically starting the process of relighting the engines, the report says. One engine was able to regain thrust, but could not reverse the plane’s deceleration, leading one of the pilots to issue a mayday call moments before the plane crashed into a building.

There had been several speculations after the crash, with some pointing to the likelihood of bird hits and others suggesting mechanical failure or design flaws of the aircraft and its engines as reasons behind the crash. This report however appears to rule them out, with the report saying that “no significant bird activity” was observed in the vicinity of the plane’s flight path, and that “At this stage of investigation, there are no recommended actions to B787-8 and/or GE GEnx-1B engine operators and manufacturers, suggesting that no significant fault has been found with the plane or its engines.”

While the report does not draw any conclusions, and it notes that investigations are still ongoing, the focus now appears to shift to the actions of the pilots. It does not identify the voices of the pilots, although both of them – Captain Sumeet Sabharwal and First Officer Clive Kunder – were experienced pilots. Sabharwal is reported to have over 15,000 hours of flying experience, and Kunder, about 3,400 hours. Both pilots, the report says, had had an “adequate rest period prior” to the flight, and had passed breathalyser tests and were cleared fit to fly.

Interestingly, the report mentions that in December 2018, the US Federal Aviation Administration issued a Special Airworthiness Information Bulletin (SAIB) highlighting that some Boeing 737 fuel control switches were installed with the locking feature disengaged. While the issue was noted, it wasn’t deemed an unsafe condition requiring an Airworthiness Directive, a legally enforceable regulation to correct unsafe conditions in a product. The same switch design is used in Boeing 787-8 aircrafts, including Air India’s VT-ANB which crashed. Since the SAIB was advisory in nature, Air India did not perform the recommended inspections. “As per the information from Air India, the suggested inspections were not carried out as the SAIB was advisory and not mandatory. The scrutiny of maintenance records revealed that the throttle control module was replaced on VT-ANB in 2019 and 2023. However, the reason for the replacement was not linked to the fuel control switch. There has been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB,” the report says.

The investigation into the crash is still ongoing and a detailed report will come out around a year’s time. This preliminary report clarifies some things, but also deepens the mystery in other ways. Did one of the pilots cut off the fuel supply? Or was there a problem, taking into account US Federal Aviation Administration’s SAIB about some Boeing 737s having fuel control switches with disengaged locking features, with the fuel switches on this aircraft?

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