NEW DELHI () - A voice recorder from the cockpit of the Air India flight that crashed last month indicates that the pilot shut off the fuel supply to the aircraft’s engines, according to a source who has been informed about initial evaluations by U.S. authorities regarding the available evidence.
Here are some details regarding engine fuel selectors, their roles in an airplane, and how they move during an Air India flight.
WHAT ARE FUEL SWITCHES?
These are mechanisms that control the supply of fuel to an aircraft's engines. Pilots utilize them to initiate or stop engines while on the ground, as well as to manually turn off or restart engines in case of an engine malfunction during flight.
Aircraft specialists state that a pilot could not unintentionally adjust the fuel valves supplying the engines. However, should these valves be altered, the impact would happen instantly, leading to an abrupt loss of engine power.
According to U.S. aviation safety specialist John Cox, there are separate power systems and electrical connections for the fuel shutoff switches, as well as the fuel valves operated by these switches.
Where can the fuel switches be found?
On an Boeing 787 operated by Air India, which has two GE-powered engines, the two fuel control switches can be found beneath the throttle levers.
The switches are designed with springs to stay in place. A pilot must initially lift the switch before moving it from "run" to "off," or conversely.
There are two options: 'CUTOFF' and 'RUN'.
What occurred during the tragic Air India flight?
As per the flight data recorder, shortly after departure, the switches for both engines sequentially changed from 'RUN' to 'CUTOFF', each transitioning one second apart. This caused the engines to start losing power.
A pilot was overheard on the flight deck audio recording questioning another about cutting off the fuel supply. "The second pilot denied having done that," the document stated.
The document failed to specify which statements were spoken by the pilot of the aircraft and which by the co-pilot.
The first officer was piloting the 787 when he questioned the captain about moving the fuel switches to a setting that cut off engine fuel supply and asked him to reinstate the fuel flow, according to an individual informed about initial evaluations from U.S. authorities.
According to the initial report, both switches were returned to the "RUN" setting and discovered in the "RUN" position at the accident scene.
According to the report, when fuel control switches are switched from 'CUTOFF' to 'RUN' during flight, each engine's control system autonomously initiates an ignition and fuel supply process to restore power.
"no rational pilot would ever switch those controls off during flight," particularly when the aircraft is only beginning its ascent, stated u.s. aviation safety specialist john nance.
(Covered by Abhijith Ganapavaram from New Delhi and Dan Catchpole from Seattle; edited by Jamie Freed)