A truck carrying wreckage of the Air India plane that recently crashed into a medical hostel and its canteen complex passes by, in Ahmedabad
Credit: PTI Photo
The preliminary report from the Aircraft Accident Investigation Bureau (AAIB) on the catastrophic Air India crash that killed 260 people has zeroed in on a critical and perplexing question: why, just seconds after takeoff, were the Boeing 787's engine fuel control switches briefly turned off, starving them of fuel?
Understanding these switches—their function, design, and what happened to them on the fatal flight—is now central to the investigation.
What are fuel switches?
At their core, fuel control switches are the master regulators of fuel flow to an aircraft's engines. Pilots use them to start or shut down engines on the ground, or in the event of an in-flight engine failure, to manually shut down or restart an engine.
Aviation experts contend that a pilot would not be able to accidentally move these switches. If they are moved, however, the effect is immediate, cutting off all power to the engines. Underscoring their robust design, US aviation safety expert John Cox told Reuters that there are independent power systems and wiring for both the fuel cutoff switches and the fuel valves they control.
Where are fuel switches located?
On a Boeing 787 like the one operated by Air India, the two fuel control switches are situated directly below the thrust levers. They are not simple toggles. The switches are spring-loaded to remain in position, meaning that to change their state, a pilot must deliberately pull the switch up before moving it.
There are only two modes: ‘CUTOFF’ and ‘RUN’.
What happened on Air India flight 171?
The flight recorder data paints a chilling sequence of events. Just seconds after the aircraft took off, the switches for both engines transitioned from ‘RUN’ to ‘CUTOFF’, one after the other, with a one-second gap between them. As a direct result, the engines began to lose power.
The cockpit voice recorder captured a baffling exchange. One pilot was heard asking the other why he had cut off the fuel. "The other pilot responded that he did not do so," according to the report, which did not attribute the specific remarks to either the captain or the first officer.
Moments later, the data shows the switches were flipped back to the ‘RUN’ position. The report confirms that both switches were found in the ‘RUN’ position at the crash site. When the switches are moved back to ‘RUN’ in-flight, the engine’s control system is designed to automatically manage a relight and thrust recovery sequence.
Commenting on the crash, US aviation safety expert John Nance told Reuters: "No sane pilot would ever turn those switches off in flight," especially as the plane is just starting its critical climb phase.