It has been learnt from the preliminary examination that the “propeller feathering” might have been the cause of the ATR plane crash in Nepal on January 15 that killed 72 people near the Pokhara international airport.
Buddhi Sagar Lamichhane, member secretary of the investigation commission formed by the government, told News18 that 10 seconds before approaching runway 12, the propellers of both engines went into feathering on the base leg of the aircraft.
“This means that the plane’s blades are straightened without being spread according to a certain degree,” he said. “Usually this happens only after starting the landing approach.”
He said that the commission is investigating the technical and human aspects of why the propellers of both engines feathered.
According to another member of the committee, when the propellers go to feathering, the power of the engine will gradually be reduced. At that time the aircraft cannot fly as fast as before.
He said that the plane, Yeti Airlines flight 691, may have crashed before reaching the runway after the engine power suddenly decreased. According to him, when the power of the engine decreased, the aircraft might have stalled.
The chart above shows how the altitude of the aircraft decreased. It also strengthens the suspicion that the plane might have stalled, according to the members of the probe committee.
The above-mentioned committee member said that a primary report of the probe panel is being prepared, covering this issue.
The commission reached this conclusion from data analysis of both the flight data recorder and the cockpit voice recorder sent to the Transport Safety Investigation Bureau (TSIB) in Singapore.
A team including ex-secretary Nagendra Prasad Ghimire, coordinator of the commission, engineer Deepak Prasad Bastola, and senior captain Sunil Pradhan also went to Singapore for the investigation. During that time, various flight and technical aspects were also examined.
Problems of runway 12
According to Premnath Thakur, head of Tribhuvan International Airport Civil Aviation Authority, the crashed plane was supposed to land at Pokhara International Airport at 10.52 Nepali time on that day.
According to the Air Traffic Controller (ATC) of the airport, this aircraft was in contact with Pokhara International Airport until 10.50 am. At the last contact, the pilots were told to land on runway 30.
According to ex-pilot Om Gurung, this runway is known as Direct Approach Landing.
However, the flight crew members chose runway 12, where they had to fly towards the old Pokhara airport and land.
ATC gave permission as there was no traffic problem. However, the plane suddenly crashed into the Seti Gorge while adjusting the nose on runway 12 of the airport, which was 1,800 metres ahead.
Why? The investigation committee formed by the government has said that the power of the plane may have suddenly decreased. Although the reason behind this is being investigated, it is suspected that there may been an error by the pilot Kamal KC and his assistant.
According to an official, KC’s aide Anju Khatiwada sat in the left seat because that flight was also an ‘examination’ to get the Pokhara flight clearance for her. The main pilot who controls the aircraft sits on the left.
Officials from the investigation committee said instructor pilot KC may have been sitting as a passenger after giving the entire responsibility of the aircraft to Khatiwada. The officials suspect that Khatiwada may not have noticed that the plane’s power was reduced when she was only concentrating on adjusting the line on the runway as it was about to land.
“If the power had been increased, the aircraft would have remained in the right position,” said an official from the committee, “But, she did not notice the continuous decrease in power; even the pilot KC did not notice.”
Thus, within one minute of the last contact with Pokhara International Airport, the biggest plane crash in the history of Nepalese domestic flights took place, according to the officials.
Disaster on easy route
In the aviation sector, the air route from Tribhuvan International Airport to Pokhara is considered easy. However, an ATR plane of Yeti Airlines crashed on the same route, killing 72 people.
According to Assistant Chief District Officer of Kaski, Anik Shahi, 71 dead bodies have been found at the crash site so far. One person is still missing.
According to Sanjeev Gautam, former Director General of Nepal Civil Aviation Authority, this is the biggest air accident that has happened on the internal route of Nepal so far in terms of human casualties. On top of that, he said that it was surprising that an accident took place on a route that was supposed to be easy.
Chief of Tribhuvan International Airport Civil Aviation Office, Premnath Thakur, also said that it is surprising that the accident happened when the permission for landing of the aircraft had already been given.
According to officials, the visibility of Pokhara International Airport was 7 km at the time of the crash. An aeroplane can land in Pokhara within 5 km visibility. The wind speed was 5 and a half kilometres per hour. Therefore, there was no situation that would hinder the landing.
Serious challenge for Nepal’s aviation sector
The European Union (EU) has been banning Nepali Air Service since 2013. The EU has banned the Nepali aviation industry, raising questions about increasing air accidents, air safety, and regulations.
Achyut Pahadi, an air security expert who retired after working for a long time in Nepal Airlines, says that this accident, which caused great human loss, has increased the risk of the EU ban being extended further.
This accident is the 58th in the aviation history of Nepal. According to the Civil Aviation Authority’s Aviation Safety Report, 2022, 363 passengers have died in those accidents so far. 139 passengers on the crashed plane were rescued alive.
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