An investigation report has revealed that the pilot of US-Bangla Airlines Flight BS211 from Dhaka, Bangladesh, "seemed to have an emotional breakdown" before a fatal crash last March.The aircraft crashed on its second landing attempt at Kathmandu's Tribhuvan International Airport on March 12, 2018. The accident, which killed 51 people and injured 20 others, was Nepal's worst aviation disaster in 26 years. The pilot and co-pilot also perished in the crash. The report states that the likely cause of the accident was the pilot's disorientation and loss of situation awareness."Landing was completed in a sheer desperation after sighting the runway, at very close proximity and very low altitude," it says.

The pilot, 52, was reportedly stressed and "emotionally disturbed" after an argument with a colleague who questioned his reputation as an instructor, Nepal's Accident Investigation Commission said. The report also stated that the pilot had been dismissed from the Bangladesh Air Force in 1993 due to depression. In 2002, he was authorized to fly commercial planes after a medical evaluation.

According to witnesses and audio from the voice recorder, the pilot was reportedly smoking in the cockpit during the flight and "engaged in unnecessary, unprofessional and lengthy conversation even in the critical phase."

Kathmandu airport, which is surrounded by hills, is notoriously difficult for landing. In 1992, a Pakistan International Airlines airplane crashed into a hill as it was trying to land, killing all 167 passengers and crew members on board.

The investigation report advises the airline to establish procedures to evaluate the mental status of the crew as relates to professional development, as well as financial, personal and psychological issues. Pilot mental health was addressed in the airline industry after a Germanwings first officer deliberately flew an airplane into a mountainside in 2015.

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The Germanwings pilot, who was flying an Airbus A320-211 from Barcelona to Düsseldorf, crashed in the south of France near Digne-les-Bains. The flight, which was carrying 144 passengers, two pilots and four cabin crew, had no survivors. The investigation revealed that the crash was intentionally caused by the co-pilot, 27-year-old Andreas Lubitz, who had taken time off from his flight training in 2009. At the time, he told the Flight Training Pilot School that he had suffered a "previous episode of severe depression." Before training as a commercial pilot, he had been treated for suicidal tendencies.

Last year, the European Commission adopted new mental health rules for pilots, requiring airlines to conduct a psychological assessment before contracting them.