South Asia

Nepal Tragedy: A Plane Crash, a Leaked Tape and a Few Unanswered Questions

From a fatigued pilot to confusion over runways and miscommunication with the control tower, unearthing the possible reasons behind the crash.

A Bangladeshi aircraft – carrying 36 Bangladeshis and 33 Nepalese – crash landing at a Nepali airport, and killing over 20 people each of both the countries, is a tragedy of a large scale.

The crash of US-Bangla flight BS-211 at Tribhuvan International Airport (TIA) is the greatest aviation disaster involving a Bangladeshi airlines, and the third biggest one at the TIA in Nepal.

The 78-seater Bombardier Dash 8 Q400 had a total of 71 passengers – one Chinese (who also died) and one Maldivian, beside the Nepali and Bangladeshi passengers totalling 67. All four crew members, including the pilot, were from Bangladesh.

After taking off from the Bangladeshi capital city of Dhaka on March 13, the plane crash-landed at the Nepali capital Kathmandu after a 75-minute trip. It landed east of TIA’s lone runway and skidded into a nearby football field. A total of 49 people had died during the crash, including the crew members.

Rescuers who immediately reached the crash site had to cut apart the mangled and burned wreckage of the upturned aircraft to pull people out, some of whom were burned under the scattered debris.

News and photos of the crash, and the eventual rescue operations, had soon surfaced on the internet. While in the past people have relied on broadcast or print media for updates on such incidents, now a smartphone with an internet connection is all that’s needed. This culture has given birth to a certain kind of immediacy to the tragedy that did not exist before.

The condition of the victims – made available to the world through social media – helps us understand the gravity of the tragedy from a position which certainly was absent before.

There, however, is another side to this culture. The photos, videos and audio recordings of the incident can now also lead to speculation, confusion and the eventual buck-passing among the parties involved – which has happened in the current disaster.

A recording of a conversation between the captain of the flight BS-211, Abid Sultan, and the officials of the Air Traffic Control (ATC) of TIA, just before the crash landing, has been uploaded on YouTube by an unknown source, stirring up all kinds of speculations in the past few days.

The Civil Aviation Authority of Nepal (CAAN) did not directly confirm the authenticity of the leaked conversation, saying that the publication of such exchanges was against the law. Raj Kumar Chettri, the general manager of the airport, told Reuters that the police would investigate how the audio was leaked.

A fatigued pilot?

The leaked conversation revealed confusion over the designated runway. The Kathmandu airport has a single 10,007 feet (3,050 m) concrete runway orientated 02/20 – which indicates the direction to land or take off.

All runways across the world are numbered based on the magnetic azimuth in which the runway is oriented. Here 02 means 20 degree on the compass towards the northeast, so the airplane has to approach it from the northern end. (The opposite end has to be 180 degree apart, in this case, at 200 degree at the northwest, so the airplane has to approach it from the northern end. In runway numbering system, the last digit of the degree is dropped so the TIA’s lone runway is numbered as 02/20).

The conversation between the pilot and the ATC revealed that the control tower asked the captain to hold the current position and not proceed towards runway 20, which the latter agreed to. A few moments later, the ATC cleared flight BS-211 for landing and asked whether it would approach the runway from the southern end – which is 02 – or the northern end, which is 20. Pilot Sultan said he would land through 20.

Even though the pilot had sought permission for 20, a few moments later, he said: “Cleared to land runway 02.” The ATC official, who was seemingly confused by this, however, also cleared him to land on runway 02. The last recorded words of pilot Sultan were: “Sir, are we cleared to land?” After some silence, the seemingly alarmed ATC controller shouts, “I say again, turn…!”. There is silence for a while; then a ‘Fire One Station’ calls the tower, indicating that a crash has occurred.

By listening to these few minutes of conversation, any layman could have understood that there was confusion from both ends.

It was later found that the pilot was on his fifth flight of the day. Earlier on that day, he made two Dhaka-Chittagong-Dhaka flights. Some experienced pilots told The Wire that multiple take-offs and landings on a single day can seriously tire out even the most seasoned pilots.

US-Bangla Airlines’ general manager, Kamrul Islam, however seemed to differ. According to him, the pilots of their airlines do not usually have any problem taking on such workload.

“Dhaka-Chittagong-Dhaka is a 45-50 minute flight in both ways and Dhaka-Kathmandu-Dhaka is 1-1.15 hours both ways. So making three such [return] flights on a day is not abnormal,” he said.

Islam, who has been with US-Bangla since 2015, told The Wire that Sultan was a former Bangladeshi Air Force pilot, and was specially trained for landing in a critical airport like TIA. “He had landed at Tribhuvan more than 100 times. He also had over 5,000 hours of flying experience of commercial airlines, so I believe it was not the pilot’s error,” he said.

Why the confusion over selecting runways?

Seasoned pilots who have experienced the Dhaka-Kathmandu route, have spotted “more severe cockpit error” in the leaked conversation. They, however, have declined to comment on the record. One senior pilot of the state-owned Biman Bangladesh Airlines told The Wire that usually, an aircraft containing over 70 seats doesn’t approach from the North towards the side of the runway marked as 20. This route is usually taken by smaller 22-30 seater aircrafts.

The approach to runway 20 is made through a gap in the southern range of mountains On the approach path profile, there is a mountain peak at 7,688 feet. The minimum segment altitude over this mountain is 8900ft leaving a clearance of around 1212 feet only.

This gap is very little for a large aircraft to manoeuvre in the thin air of Kathmandu which itself is situated at 4,500 feet, said the pilot with Biman adding: no aircraft of Biman has landed from that end in the last 15 years and it is written in Biman’s manual not to land from that end.

“There were instances where we came back from Kathmandu to Dhaka with aircraft full of passengers as we couldn’t approach a landing from Southern side where the runway is marked as 02, due to wind pressure or bad weather. But we didn’t approach landing from Northern end. I am surprised that the US-Bangla flight which had an experienced pilot like Sultan, tried landing from that end,” he said.

The Biman pilot also said as Tribhuban airport is a special airport due to its surrounding mountaineering terrain, the main pilot maneuvers the plane during landing and/or take-off, and the co-pilot communicates with the control tower.

But, the senior pilot of Biman said, the audio revealed that both the landing and communication were carried out by the main pilot Sultan even though the communication should have been done by the co-pilot: Prithula Rashid.

“It seemed he [Sultan] was maneuvering the plane and talking to the tower at the same time which made him loose concentration and lost sight of the runway while switching from runway 20 to runway 02. In Tribhuban, keeping the runway in sight all the time is a must,” said the Biman pilot.

Can the control tower stay out of blame?

Another pilot with a foreign airline that The Wire talked to did not give the ATC of Tribhuban a clean chit. The tower influenced the pilot to follow a non-standard approach by asking to hold, which is not acceptable in Kathmandu due to terrain, the pilot said.

The tower also cleared the US-Bangla aircraft to land on runway 02 only three minutes after allowing a Jet Airways flight, a Boeing 737-800, from Mumbai to land on the same runway. And midway through its conversation with pilot Sultan, the tower cleared another aircraft (Buddha282) to land on runway 02. These activities of the ATC obviously poses question, added the pilot with the foreign airlines who also listened and analysed the leaked conversation.

Sanjiv Gautam, director general of the CAAN, however, saw no wrong signals given to US-Bangla pilot. “The weather was clear. The pilot had minimum five-kilometre visibility. The pilots confirmed that the runway was visible… (yet) the pilots were not following our instructions,” he told CNN. “The aircraft displayed uncontrolled movement during landing. The alignment wasn’t right; it was tilted on one side.”

The pilot with the foreign airlines told The Wire that there are also other problems with the Tribhuban airport. It does not have any instrument landing system, because of which a pilot cannot conduct a predetermined manoeuvre landing if s/he is unable to establish visual contact with the runway, he said.

“The landing at Kathmandu because of the terrain is a little challenging,” Gabriele Ascenzo, a Canadian pilot who runs aviation safety courses in Nepal told AFP. Depending on the direction of approach, pilots have to fly over high terrain before making a steep descent towards the airport, Ascenzo added.

AP reported that Nepal’s poor air safety record is largely blamed on inadequate maintenance, inexperienced pilots and substandard management, and its planes are banned from flying in European airspace.

Accidents are common, hitting the impoverished country’s vital tourism industry. In early 2016, a Twin Otter turboprop aircraft slammed into a mountainside in Nepal killing all 23 people on board. Two days later, two pilots were killed when a small passenger plane crash-landed in the country’s hilly Midwest, said the AP report.

Was there any problem with the aircraft?

Meanwhile, a video of the BS-211 few minutes before it crashed, obtained by a local news portal of Nepal named shikharnews.com added more fuel to the fiery debates going on about unearthing the possible reasons behind the crash.

The video shows the flight 211 nearly crashed at a foothill of a hill. The aircraft, however, managed to lift with white light visible from the wing tip that illuminate the terrain. Locals are heard chatting: “The aircraft has lost its way. It is flying. It is flying.”

Data from tracking website Flightradar24.com showed that flight BS-211 descended to an airport altitude of 4,400 feet (1,341 m) and then climbed to 6,600 feet (2,012 m) before crashing about two minutes later, the website said.

Passengers who survived the crash hinted some problem with the aircraft too. The Kathmandu Post reported that some passengers said they had sustained shuddering few minutes before the crash followed by a loud bang.

Ashish Ranjit, a travel agency operator in Balaju, recuperating at Norvic International Hospital, Thapathali told the newspaper, “Before the incident, I could sense the danger, the plane was wobbling horribly. I was scared and called an air-hostess. She raised her thumb indicating everything is ok,” he said.

But apparently it had proven to be anything but “ok” within the next few minutes.

According to Captain Salahuddin M. Rahmatullah, chief of the Aircraft Accident Investigation Group of Bangladesh, the committee instituted to look into the incident, the aircraft had no “technical glitch before taking off for Kathmandu”.

How long it could take to learn the truth?

Experts concerned with aviation disaster said, a lot of speculations could be made about the possible reasons behind the disaster but nothing could be confirmed before conducting a thorough investigation basing on the data of the Flight Data Recorder (FDR) which is popularly known as “black box.”

The black box of flight BS-211 was retrieved on Tuesday and CAAN had already formed a six-member committee to probe the crash-landing. Civil Aviation Authority of Bangladesh (CAAB) Chairman Air Vice Marshal M Naim Hassan informed that a Bangladeshi delegation comprising CAAB officials also went to Kathmandu to provide assistance to the committee.

According to rules set out under the Convention on International Civil Aviation (ICAO), the primary role in the probe goes to the country where a crash occurs, but the states where the aircraft was registered, where the airline was based and where the plane was designed can all have a role.

On Thursday, at a media briefing, Hassan hinted that completing the investigation could take a year or more. “Completing the investigation of such air accidents may take a year or even more,” he said.

The US-Bangla Flight-211 crash is the third biggest aviation disaster in Nepal’s history. Earlier, in 1992, within a span of a little over two months, Thai Airways Flight-311 and PIA Flight-268 crashed killing 113 and 167 people respectively, and entered into the record book as the second and third deadliest aviation disasters in Nepal’s history.

As the reasons behind the Thai Flight-311 crash, it is stated in the journal of International Flight Safety Foundation (IFSF) that the accident occurred because the pilot tried to approach the airport in a situation of lower than minimum visibility amidst heavy rain and could not maintain the course as set down in the approach chart. It also said the airport lighting system and approach chart did not facilitate the low visibility approach.

IFSF records of the Flight-268 crash suggests that the primary cause of the accident was that one or both pilots consistently failed to follow the approach procedure and inadvertently adopted a profile which was one altitude step ahead and below the correct procedure.

Why and how that happened could not be determined with certainty because there was no record of the crew’s conversation on the flight deck. Contributory causal factors were thought to be the inevitable complexity of the approach and the associated approach chart, said the IFSF about the largest aviation disaster that took place on Nepalese soil.

Canada-based Bangladeshi aerospace engineer Nakib Khan, who had worked in Bombardier—the maker of the Dash-8 Q400 which had crashed—told The Wire that investigating an aviation disaster is no small task.

“Investigation will be conducted by several parties, including the aircraft-maker, civil aviation authorities of the country where the plane crashed, the insurance companies involved and, if needed, the International Civil Aviation Authority (ICAA),” he said.

About the possible method of investigation, Khan said the aircraft wreckage is normally re-assembled as much as possible. The pieces of physical evidence, even if initially hidden or distorted by the impact of hitting the ground or other factors, can start to suggest lines of inquiry, along with the “black box” and cockpit voice recorder, Khan added.

After the initial phase of gathering physical intelligence, it is normally possible to form a view of the physical process that brought the aircraft down – for example, an explosion, said the engineer, who had graduated in Aerospace engineering from Toronto’s Ryerson University.

The results of autopsies performed on passengers and crew can also help narrow down what happened on board, he said, adding that the accident investigation process is very strictly a no-blame process. If investigators believe they have found a design or maintenance fault, they can issue recommendations immediately in order to try to prevent the problem affecting other aircraft, long before any final report is published, said Khan.

Faisal Mahmud is a journalist from Bangladesh.