Nepal Airlines Flight 555

Nepal Airlines Flight 555 was a short domestic scheduled flight from Pokhara Airport to Jomsom Airport in Nepal of about 20 minutes' flying time, operated by Nepal Airlines. On 16 May 2013, the de Havilland Canada DHC-6 Twin Otter aircraft operating the flight crashed while landing at Jomsom Airport. Seven of the twenty-one on board were seriously injured. There were no fatalities, but the aircraft was damaged beyond economic repair.

Aircraft & Crew
The aircraft involved was a de Havilland Canada DHC-6 Twin Otter bearing the registration 9N-ABO. It was built in 1979 and had been operated by Nepal Airlines ever since. Following this incident, the aircraft was written off.

The captain was Pradhan Dipendra 39 years old, with 8,451 total hours, 8,131 of those on the DHC-6. the first officer was K.C. Suresh 29 years old, with 1,396 total hours, 1,202 of those on the DHC-6. Both pilots are Nepali citizens.

Passengers
There were eight Japanese tourists on the flight. All sustained injuries, with four of them in a critical condition, according to a police officer.

Accident
While descending towards Jomsom, aerodrome flight information service (AFIS) informed the crew about southwesterly winds at 8 to 12 knots, runway 24 was in use. The first officer accepted runway 24 reading back they would report on downwind runway 24. Without discussion the captain took communication over from the first officer and requested runway 06, responded to the query by ATC that 8-12 knots were no problem, ATC therefore assigned runway 06 to the aircraft. A go-around briefing by the captain contained just one word: "standard".

The aircraft was configured for landing with full flaps and touched down on runway 06, 776 feet past the runway threshold. About 194 feet after touchdown the aircraft left the runway surface and entered soft ground to the right of the runway with the maximum deviation being 19 feet from the right-hand runway edge. In the meantime, the first officer, without communication taking place between the pilots, worked the after landing checklist and retracted the flaps.

While attempting to return the aircraft onto the runway the captain increased engine power with the intention to go around, the aircraft however had already lost a lot of speed due to application of brakes by the captain. Nonetheless, the aircraft accelerated but reached insufficient speed to produce sufficient lift for becoming airborne. The aircraft overran the end of runway 24, continued towards the river, ran through a barbered fence and gabion wall before falling down onto the edge of the river.

The captain, first officer and a female passenger received serious injuries, the flight attendant and 6 passengers received minor injuries, 11 passengers remained uninjured. The aircraft received substantial damage including the right-hand wing being sheared off the aircraft.

According to police, just after the aircraft touched down on the runway it veered towards the right and fell 20 metres (66 ft) down the bank of the Gandaki River. The forward fuselage was destroyed, but the rear of the aircraft remained intact. The left wing was found submerged in the river.

Investigation
An investigation was carried out to determine what caused the accident. According to an official at Tribhuvan International Airport, preliminary reports had shown that windy conditions could have played a part in the crash.

The CAAN quoted observers on the ground stating that after the aircraft had veered right onto grassy surface the aircraft sounds changed as if a takeoff was attempted and the speed of the aircraft increased. The CAAN analysed that according to the first officer's statement the approach speed was more than 100 knots while STOL (short takeoff and landing) procedures require an approach speed of 70 knots +/- 5 knots.

The weather, facilities and runway conditions at Jomsom were not contributing factors to the accident. The aircraft's technical and loading condition were also not considered contributing factors.

The captain was experienced and had been checked out one by one to operate into STOL aerodromes by the instructor pilots. Nonetheless, the CAAN analysed, " the STOL landing procedure undertaken by PIC and the final decision taken in this flight were inappropriate." The CAAN analysed that AFIS on STOL aerodromes had been given the authority by Nepalese regulations to declare a runway closed provided there were tail winds in excess of 10 knots.

On 18 February 2014, the Civil Aviation Authority of Nepal (CAAN) released their final report concluding the probable causes of the accident were:

The inappropriate conduct of STOL procedure and landing technique carried out by the PIC, during landing phase and an endeavor to carry out take off again with no sufficient airspeed, no required lifting force and non-availability of required runway length to roll. A contributory factor was the absence of proper CRM in terms of communication, coordination and briefing in between crew members on intention and action being taken by PIC, during pre and post landing phase.

Aftermath
The accident left Nepal Airlines with only two operational aircraft for its domestic flights. The airline said that it planned an engine exchange that would put three more Twin Otters, currently grounded, back in the air, but that process would take at least five months. In the meantime, the airline was expected to suffer a significant loss of market share.

Contrary to common practices in aviation, Nepal Airlines did not retire the flight number 555 and still operates the flight from Pokhara to Jomsom under this number.