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.

An investigation is underway as to what caused an Air India airliner carrying 230 passengers and 12 crew members to crash shortly after takeoff on Thursday.

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.