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.

Captain Kishore Chinta, a former investigator with India's Aircraft Accident Investigation Bureau (AAIB), calls this "the rarest of the rare" crashes - a controlled flight into terrain just 30 seconds after take-off. "To my knowledge, nothing quite like this has ever happened," he told the BBC.

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.