Nepal crash: final report details erratic, dangerous maneuvering
Investigators have released the final report into the crash that took the lives of 51 people last March, detailing the disturbing behavior of the captain and the erratic course of the aircraft in its final moments of approach at Kathmandu, Nepal.
The inquiry asserted that both crew members failed to follow the standard operating procedure at the critical stage of the flight, which contributed to “loss of situational awareness” and resulted in the aircraft missing the runway.
Apparently, the flight course taken by the aircraft was not only “unusual and abnormal” but also dangerous; so much so that at one time the air traffic controllers had to duck below their tables believing the aircraft was heading for the tower.
On March 12, 2018, Flight BS211 operated by US-Bangla Airlines (Bangladesh) departed from Shahjalal International Airport (DAC) in Dhaka, Bangladesh, at 6:52 UTC with 71 people, including four crew members and 67 passengers, onboard.
On its final approach to runway 02 at Tribhuvan International Airport (KTM) in Kathmandu, the capital of Nepal, the Bombardier Dash 8-Q400 (S2-AGU) crashed on impact with the runway, bursting into flames and killing 51. The accident was declared as the Himalayan nation’s worst aviation disaster in 26 years.
According to the final report into the fatal crash by Nepal’s Accident Investigation Commission (AIC), released on January 29, 2019, the US-Bangla Airlines jet crashed about 442 meters (approx. 1450 feet) southeast of the touchdown point of runway 20, just outside the inner perimeter fence of the landing strip.
“The aircraft hit the runway at an IAS of 127 knots and a heading of 190 degrees and immediately departed the runway surface towards the southeast direction in an uncontrollable manner further impacting the inner periphery fence, descending downslope and finally bursting into flames,” the document reads.
Investigators discovered that problems emerged after the DHC-8-400 was cleared for a VOR approach to runway 02. According to the report, while performing their flight duties, “the flight crew were busy discussing their personal issues and worries”. As a result, the pilots apparently forgot to cancel a hold instruction in the flight-management system. They only realized their mistake when the aircraft started turning left to enter a holding pattern.
To correct the deviation, the captain selected a heading of 027 degrees towards the final approach inbound track overriding the FMS (Flight Management System) LNAV (Lateral Navigation mode) guidance in a hurried attempt to continue the approach as cleared. Data also revealed the plane was experiencing strong westerly winds, due to which the plane overshot the radial and continued to drift towards the east of the approach path.
“The PIC kept on assuming that the landing runway was still ahead of them, though the aircraft had already flown through the eastern part of the entire RWY at a position beyond the north east of RWY 20 threshold, approximately 3-4 NM northeast of KTM VOR. Autopilot was disengaged at 1.1 nm east of the VOR,” the report indicates.
When the aircraft reached this position, having flown to the northeast of the airstrip, the Kathmandu tower controller informed the pilots that, while landing clearance had been granted for runway 02, they were heading for runway 20 in the opposite direction.
“At this moment the tower OJT controller was replaced by the Tower Duty Controller who took over the microphone and mistakenly cleared the flight to land on RWY 20 on share assumption, in considering with the aircraft’s current visual flight position that it could be pilots’ intention to land on RW 20 though the PIC deliberately transmitted that he would land on RW 02.”
Clearly struggling to find the runway, flight BS211 continued towards the northeast on the same heading. According to the report, the captain began maneuvering the aircraft on a right-hand orbit exiting towards the west after a three-quarter turn, before crossing perpendicular to the extended centerline of runway 20. The ATC cleared the flight to join the right-hand downwind for 02.
“Desperate to find the landing runway and still unaware of their position, compounded by threatening high terrain all around and multiple EGPWS warnings [Enhanced Ground Proximity Warning System], the commission concluded that there was a complete loss of situational awareness on the part of the flight crew at this stage.”
By then, another incoming flight, a Buddha Air aircraft, was on final approach having been granted clearance to land on runway 02. As flight BS211 kept heading towards runway 20 instead of joining the right downwind for 02, the Kathmandu tower instructed the plane to hold position and remain clear of runway 20.
“At this time, the aircraft had already flown past north abeam threshold RWY 20 on a westerly heading of 280 degrees at 3.2 DME north from the VOR at 6000 ft. The aircraft continued to climb to 6500ft until when the PIC then again started maneuvering the aircraft on a steep right hand orbit, on the northwest sector and admitting to the FO that he had made a mistake as he was constantly talking to her.”
The data retrieved from the CVR (Cockpit Voice Recorder) revealed that another local pilot from the ground raised concerns to the control tower that the pilots of the DHC-8-400 seemed to have been disoriented and lost. Although the ATC had offered the flight to land on either runway, the pilots continued to “anxiously” try and locate the runway, entering another right-hand orbit, north-west of the airport.
“The CVR revealed that both pilots made several statements which reflected that they had now completely lost their orientation of the runway, but this was not communicated to the ATC.”
The plane orbited through a south-east heading of approximately 160 degrees at an altitude of 5400ft (approx. 1646 m), crossing the extended centerline again, when the captain finally affirmed he could see the runway and requested landing clearance once more.
“Though it appeared unmanageable to land the aircraft on RWY 20 from the current position, attitude and altitude; for some undetermined reason, the PIC initiated desperate maneuvers in an attempt to put the aircraft on ground and requested landing clearance again affirming that he had the RWY in sight now.”
The FDR (Flight Data Recorder) data showed that in a late effort to regain the centerline, the aircraft turned right but overflew the threshold of runway 20 at 450 ft (approx. 137 m) above the ground on a westerly heading of 255 degrees.
Seeing the “reckless and irresponsible maneuvers” being carried out at very close proximity to the ground within the landing strip periphery, the ATC cancelled the landing clearance. At one point, the ATC even thought the aircraft was heading for the tower.
The DHC-8-400 missed the tower and descended on a south-east heading towards the center of runway 20, banking to the right and touching down on its right-hand main landing gear, 25 degrees off the centerline heading. The aircraft then immediately suffered runway excursion impacting the inner periphery fence before catching fire.
“Finally, when the crew sighted the runway, they were very low and too close to runway 20 and not properly aligned with the runway. For reasons unknown, probably in desperation to land, the PIC maneuvered the airplane in a very unsafe manner by forcing it to land while in a turn, with the right bank, at an angle of about 15 degrees with the RWY axis resulting the right main landing gear to make hard impact on the left of the centerline of runway 20, approximately 1700 meters from the threshold,” the report concludes.
Determining the Cause
Due to the confusion and conflicting communication between the cockpit and the air traffic control in Kathmandu, it was initially thought that poor communication with the tower control may have been to blame, especially regarding the flight crew’s intentions and clearances for runways 02 and 20. The final report by the Aircraft Accident Investigation Commission, however, asserts the ATC in Kathmandu had no wrongdoing and performed to the best of their ability.
The inquiry states that the aircraft, DHC-8-400 (S2-AGU), had been maintained in compliance with the regulations and was airworthy at the time of the accident. The two flight crew members were also licensed and qualified for the flight.
The probable cause of the accident, hence, points to “disorientation and a complete loss of situational awareness in the part of crewmember,” that being the captain of flight BS211. Aside of his disturbing emotional state, investigators point to a series of blunders during the final approach that were, in fact, committed not only by the captain, but also the first officer.
What the report stresses most is that the flight crew failed to conduct a complete approach briefing, described as “unstructured and inconsistent” by investigators and seemingly indicating the experienced captain’s “complacency”, especially given that the flight officer was operating this flight for “the very first time”.
What eventually led to the fatal impact with runway, the report indicates, was the failure on the part of both crew members to “follow the standard operating procedure at the critical stage of the flight, which contributed to loss of situational awareness to appreciate the deviation of the aircraft from its intended radial that disabled them sighting the runway.”
Due to this loss of situational awareness and despite the “multiple” ground proximity alerts, the captain made a last-ditch effort for the runway, performing dangerous maneuvers at very low altitude while facing the surrounding high terrain. When the crew eventually sighted the runway, the aircraft was very low and too close to runway 20 and not properly aligned with the runway.
“The investigation commission concludes that as a result of flight crew’s failure to complete the approach briefing as per the Standard Operating Procedure, the PIC and the first officer did not have a shared understanding of how the approach was to be managed and conducted. Both pilots failed to recognize their lack of compliance to prescribed procedures and “threat identification techniques”, the report reads.
“For reasons unknown, probably in desperation to land, the PIC maneuvered the airplane in a very unsafe manner by forcing it to land while in a turn, with the right bank, at an angle of about 15 degrees with the RWY axis resulting the right main landing gear to make hard impact on the left of the centerline of runway 20, approximately 1700 meters from the threshold.”
There was no attempt made to execute a go around when that option was still possible until the aircraft hit the runway. The CVR also recorded the landing gear alert was “continuously” blaring over the flight deck speakers, but was “constantly” disregarded by both pilots.
The report, however, also details that the captain insisted the flight officer for the landing checklist. At one point, the first officer had even affirmed that it was already completed even though the landing gear alert remained activated.
The investigation commission does paint a picture of the captain being overwhelmed with his duties as well as his personal issues. “The PIC was trying to perform his role as pilot flying, instructor coaching the first officer about various aspects of flying and operations environment in VNKT. These factors might have escalated his flight duty workload even further.”
Based on flight recordings, investigators believe the captain “was constantly trying to prove his professionalism and reputation as a competent trainer in front of a junior trainee in this flight.”
Both the captain and the first officer died in the crash.
For the inquiry findings regarding the pilot's emotional state during the flight, please read here:
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