Indian investigators on Sunday began examining the black box of a Boeing-737 that overshot a runway on its second attempt, killing 18 people in the country’s worst aviation accident in a decade. The black box of Air India Express flight that crash-landed at Kozhikode airport on Friday was brought to Delhi on Sunday.

The aircraft fell into a valley and broke in half. The 2,700-metre runway at the airport is known as a “table-top”, an aviation term for runways with steep drops at one or both ends. Directorate general of civil aviation (DGCA) chief Arun Kumar has said the tabletop runway at Kozhikode airport was long enough for the aircraft but a late touchdown may have caused the plane to overshoot the runway.

More than 50 passengers injured in Friday’s crash of the Air India Express plane in Kerala’s Kozhikode have been discharged from hospitals, the airline said on Monday.