Loss of situational awareness blamed for NAC crash

KATHMANDU, JUN 06 - Loss of situational awareness in the cockpit led to Nepal Airlines Twin Otter crash in Masinelek, Argakhanchi, on February 16, 2014, killing 18 people, according to an investigation report released on Thursday.

The report said the pilot flew inadvertently into a whiteout, lost situational awareness and lost control of the aircraft, which resulted in an impact with the terrain at an altitude of 7,190 ft.

Situational awareness basically refers to being aware about what is going on so that one can figure out what to do. Lacking or inadequate situation awareness has been identified as one of the primary factors in accidents attributed to human error.

The Canadian-made 9N-ABB, DHC-300 Twin Otter initially chopped a small tree and then hit the sloppy ridge with a huge impact. The nature of the crash was “Controlled Flight into Terrain”. This means, an airworthy aircraft, under the pilot’s control, unintentionally hit the terrain. The report, however, ruled out initial speculation that the aircraft faced an icing problem as the minimum temperature outside was zero degree Celsius as icing occurs only below minus 15 degree Celsius. The report also ruled out any engine failure and other causes like pilots fatigue.

The aircraft was completely damaged and wreckages were scattered around 2km over and beyond the hill. The crash site was located on Feb 17, a day after the crash.

The 43-year old aircraft had departed Kathmandu to Pokhara for refueling and then took off to Jumla

despite adverse weather conditions en-route.

“Pilot-in-command Shankar Shrestha was told not to fly on such a weather condition by the flight

dispatcher, airlines staff and his collogues (pilots from other airlines), but he decided to take a risk,” said Tri Ratna Manandhar, chairperson of the investigation panel. Shrestha was assisted by Rabindra Banjara as a co-pilot.

The investigation committee suspected the flight captain, in order to win the confidence of his company, decided to conduct the flight. He had completed training for Airbus jets too, and was expecting that the management would appoint him to fly the Airbus aircraft which is scheduled to be delivered to Nepal Airlines by February 2015.

Besides, the fact that the captain had only flown 11 hours in a week before the crash could have forced him to add his flying hours, according to the panel members. His assistant had not conducted any flight in the week.

After the completion of the Jumla flight, the aircraft was scheduled to night-stop in Nepalgunj, and conduct a series of flights the next day.

The report said 4 minutes after Captain Shrestha flew the aircraft from Pokhara to Jumla, he decided to turn the aircraft to the south track (Bhairahawa side), from its usual north side route—Dhorpatan-Dolpa-Jumla— due to whiteout and heavy rain. “The reason, Shrestha decided to turn the plane, was that he had penetrated the visible moisture without having proper anti-icing or de-icing facility in the aircraft in violation to the standard operating procedure as well as flight manual,” the report reads.

After 7 minutes flight, Shrestha said, “Be careful, it’s minus six degree to his assistant,” the report mentioned.

Subsequently, the aircraft that had climbed up to 10,500 ft started to descent. It came down to 8,500 ft and encountered zero degree temperature without icing conditions. “The captain decided to complete the mission in spite of adverse weather,” the report read. He, however, did not inform the co-pilot about the descending of the plane to below 8,500 ft.

Although, the co-pilot had suggested his captain not to descend, he did not insist his boss. “Insistence on that particular time was very necessary,” said senior Captain Prabhakar Prasad Ghimire, a member of the committee, briefing the report. To get out of the adverse weather, the aircraft was flying inside the visible moisture with no in-flight visibility. After the aircraft had reached Argakhanchi, the flight crew began to look for alternatives, and 19 minutes after its departure from Pokhara, it started to circle the area to find an appropriate way out,” Ghimire said.

“No way out, let’s go towards south and exit through Dang Valley,” the pilot told his deputy before communicating with the Bhairahawa Airport tower, informing they were diverting. The report said the flight captain then started losing his situational awareness, as a result, he inadvertently started descent making turns, the report reads. The co-pilot was still suggesting his captain: “No…don’t descent sir. Don’t turn sir.”

But the aircraft had descended too low and chopped a branch of a small tree and hit the sloppy ridge with the huge impact. It caught fire after the crash.

“There was a serious lack of crew coordination, especially in the last critical parts of the flight,” the report said. “The captain’s faulty decision, inability on the part of the co-pilot to strongly intervene the captain’s wrong actions led to the accident.”

The investigation committee has issued a number of safety recommendations, including ensuring that all fleets operated are equipped with terrain awareness warning system and developing a mechanism to obtain the real time weather data for the information and analysis of weather en-route.

The committee has asked the Tourism Ministry to establish an independent and effective aircraft accident investigation mechanism with adequate resources.