Pilot error and failure to follow safety guidelines probably led to the crash of an Air India Express plane in August last year, investigators say.

The passenger plane with 190 people on board crashed at the Calicut airport in the southern state of Kerala, killing 21 people.

The Boeing 737, which had flown from Dubai, skidded off the runway in rain and broke in two after landing.

The flight was repatriating Indians stranded by the coronavirus crisis.

The dead included both pilots. Seventy-five passengers were seriously injured.

The aircraft crashed as it attempted to land for a second time. The first attempt was aborted by the pilots because of the heavy monsoon-season rainfall lashing Kerala.

The report by India's Aircraft Accident Investigation Bureau said there were several "violations" of operation procedures before landing by the pilot.

They include that not carrying out "adequate briefing" for landing with tailwinds in rain and poor visibility, as well as failure to "quickly calculate accurate landing data in adverse weather conditions", contributed to the crash.

A non-functioning windshield wiper had also impaired visibility, the 257-page report said.