A pilot's failure to follow operating procedures led to a deadly passenger plane crash in southern India last year, an investigation by the civil aviation regulator has found.

Air India Express Flight 1344, a Boeing 737, crash-landed at Kerala state's Kozhikode airport with 190 passengers and crew abroad in August last year.

The jet overshot the runway in a storm, plunged down a bank and was destroyed, with its fuselage breaking up.

Some 21 people, including 19 passengers and the flight's two pilots, died in the crash. Another 75 passengers and one crew member were seriously injured, the report said.

"The probable cause of the accident was the non-adherence to standard operating procedures (SOP) by the PF (pilot flying)," the Aircraft Accident Investigation Bureau under India's civil aviation ministry said in its report released late Saturday.

The regulator said the pilot had "continued an unstabilised approach and landed beyond the touchdown zone, halfway down the runway, in spite of 'go around' call by PM (pilot monitoring)".

The report added that the pilot monitoring had failed to take over the controls of the aircraft and execute a "go around", where a landing approach is aborted.

The pilots had made two attempts to land in the fierce winds and rain before the crash.

The report added that the pilot flying the jet was "highly experienced" and had operated 36 flights "in and out of Kozhikode during the last one year prior to the accident".

"This experience probably resulted in complacency due to overconfidence that affected his decision making," it said.  

Even before the accident, critics had raised questions about potentially dangerous conditions at the airport.

Kozhikode is considered a tricky airport as it is built on a hill with a "table-top" runway with a steep drop at one end.

In 2017, a Spicejet Bombardier Q-400 plane carrying 75 people came off the same runway when it was wet.

The last major plane crash in India was in 2010, when an Air India Express Boeing 737-800 from Dubai to Mangalore overshot the runway, killing 158 people.

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