The preliminary finding gives investigators a new line of inquiry as they study a crash that killed all but one of the plane’s passengers.

The crash of an Air India Boeing 787 Dreamliner seconds after takeoff from Ahmedabad city, killing all but one of the 242 people on board, is the world's worst aviation disaster in a decade.

The black boxes will provide cockpit conversations and data related to the plane's engine and control settings to investigators and help them in determining the cause of the crash.