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.

Axar.az reports that, the Air India Express plane, which was repatriating Indians stranded in Dubai due to the coronavirus pandemic, overshot the runway of the Calicut International Airport in heavy rain near the southern city of Kozhikode on Friday.

The aircraft fell into a valley and broke in half.

In an interview with Reuters partner ANI on Sunday, Arun Kumar, head of India’s Directorate General of Civil Aviation, said the country would open the recovered transcripts to international investigators, as well as manufacturer Boeing (BA.N).

“Only after conducting a thorough and unbiased probe, can we tell what exactly happened,” Kumar said.