Air India plane crash report: What happens when fuel switches go from 'run' to 'cutoff'?

A preliminary report on investigation into the Air India plane crash of June 12 has revealed that the aircraft's fuel switches -- which turn the engines on and off -- were cut off moments after takeoff. They were then turned back on, but the engines failed to regain thrust. According to an in-flight voice recording, one pilot could be heard asking the other why he had cut off fuel, to which the latter replied he did not do so. But, what exactly happens when fuel switches of a plane are turned off?

When is fuel switch turned off?
Flipping the fuel switch to cutoff almost immediately shuts down the engines. It is most often used to turn engines off once a plane has arrived at its airport gate, and in some emergency situations such as an engine catching fire. However, the Air India report does not indicate if there was any emergency requiring an engine cutoff. And as per experts, a pilot would not be able to accidentally move the fuel switches. In case of the Air India flight, the fuel cutoff happened shortly after takeoff, meaning the aircraft did not have sufficient altitude or speed to glide or recover. Experts say that even if the fuel switch is turned back on, restarting the engines takes too long at such a low altitude.

What happened with Air India flight?
On June 12, a Boeing 787 Dreamliner plane operated by Air India with 242 people onboard -- 230 passengers and 12 crew members -- crashed moments after taking off from the Ahmedabad international airport, killing almost everyone on board. The accident marked one of India's deadliest aviation accidents ever. The plane crashed in a residential area close to the airport and killed dozens others on the ground. Ramesh Viswashkumar, a 40-year-old British citizen of Indian origin, is the sole survivor of the tragic incident.