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.

Yeti Airlines flight 691 crashed Sunday just before landing in Nepal’s tourist city of Pokhara, the gateway to a popular hiking area in the Himalayas, after a 27-minute trip from Kathmandu.