An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

Authorities released a preliminary report on the Air India crash, following an investigation. The London-bound flight from Ahmedabad crashed minutes into the June 12 flight. Only one passenger of the 242 passengers and flight crew survived.

Preliminary findings into last month’s Air India plane crash suggest the aircraft’s fuel control switches were turned off, causing a loss of engine thrust shortly after takeoff.