The captain of a Bangladeshi aeroplane "seemed to have an emotional breakdown" before a deadly crash last March, Nepali investigators have said in a final report on the Himalayan nation's worst aviation disaster in 26 years.
They blamed the crew's loss of situational awareness for the crash of the US-Bangla Airlines flight to the Nepali capital from Dhaka that caught fire on landing in Kathmandu, killing 51 of the 71 people aboard.
"The pilot thought he could manoeuvre the aircraft and land. But he could not," panel official Buddhisagar Lamichhane, told Reuters on Monday, referring to the captain.
The captain was under stress and "emotionally disturbed" because he felt that a female colleague who was not on board the fatal flight had questioned his reputation as a good instructor, Nepal's Accident Investigation Commission said in the report.
"This, together with the failure on the part of both the crew to follow the standard operating procedure at the critical stage of the flight, contributed to the loss of situational awareness," said the report, submitted on Sunday.
This lack of awareness meant the crew did not realise the deviation of the aircraft, a Bombardier Inc Q400 turboprop, from its intended path, which in turn meant they could not sight the runway, it added.
Having missed the runway, the crew was flying very low north of it in an incorrect position near hilly and mountainous terrain around the airport, it said.
"Finally, when the crew sighted the runway, they were very low and too close to (it) and not properly aligned," added the report, saying the captain should have halted the landing and initiated a go-around.
The plane skidded off the runway on to surrounding grass, quickly catching fire. Both pilots were among those killed.
The flight's captain, aged 52, was released in 1993 from the Bangladeshi Air Force because he suffered from depression but was later declared fit to fly civilian aircraft, the report said.
Citing the voice recorder and the eyewitness accounts of passengers, the report said the captain was smoking in the cockpit during the flight and "engaged in unnecessary, unprofessional and lengthy conversation even in the critical phase," violating the norm of maintaining a sterile cockpit.
He shared the cockpit with a first officer, 25, who had a total of just 390 hours of flying experience and had never previously landed at Kathmandu as crew, the report said.
On the US-Bangla flight, the disparity in experience and added authority of the captain probably deterred the first officer from being more assertive during significant phases such as the final approach and landing, the report said.
The report recommended the airline set up a mechanism to monitor and assess the mental status of the crew.
Pilot mental health was spotlighted by a 2015 crash in Europe after a Germanwings first officer deliberately flew a jet into a mountainside.
Last year, the European Commission adopted new rules on the mental health of pilots, for the first time requiring airlines to do a psychological assessment before hiring them.
