Investigators in India are studying the black boxes of a Boeing 787 Dreamliner after recovering them from the aircraft wreckage to ascertain the cause of last week’s plane crash that left at least 270 people dead.

Three days after the crash, only 35 bodies had been handed over to relatives from an overall official death toll of 270.

India’s deadliest plane crash in more than decade is set to send shock waves through the aviation insurance industry and trigger one of the country’s costliest claims, estimated at around $475 million.