A de Havilland Canada DHC-6 Twin Otter 300 was scheduled to operate a domestic flight in Nepal between Pokhara Airport and Jomsom Airport. Onboard the flight was a crew of 3 and 18 passengers.
The aircraft in its final position (source twinotterworld.com © Jomsom)
At 08.10 local time, the aircraft left Pokhara for the short flight (43 miles / 69 kilometers) to Jomsom. After an uneventful flight, the flight contacted ATC while descending toward their destination. ATC informed the crew that there was a south-westerly wind at 8-12 knots with runway 24 in use.
During the approach, the pilot in command contacted ATC and requested runway 06 for landing instead of the assigned runway 24, tower advised against using 06 due to the tailwind component.
The tailwind limit the operator had in the Standard Operating Procedures, was 5 knots, which was exceeded by the prevailing wind conditions and runway choice.
After the landing clearance was received the aircraft touched down 776 feet (~237 meters) past the threshold of the 2424 feet (~739 meters) long runway. 194 feet ( 59 meters) after touchdown the aircraft veered off the runway onto the grass. As per after landing procedures, the copilot had selected the flaps to up after the touchdown. While on the grass the captain added power to return to the runway and once on the runway continued to add power with the intention of going around. He never made his intentions clear to the copilot. With the flaps retracted the aircraft did not develop enough speed to generate enough lift to perform a successful aborted landing. The aircraft overran the end of the runway, and broke through the airport parameter fence, coming to a stop on the bank of the Kaigandaki River.
The aircraft in its final position (source twinotterworld.com © Jomsom)
The accident was investigated by the Aircraft Accident Investigation Commission (AAIC) of Nepal. In their report (available by clicking here). The following overview of injuries is shown in the report;
Among others, the following conclusions were listed;
There was no evidence of system or component failures that could have contributed to the accident.
The captain opted to land at runway 06 against the advice from the tower, without consulting the co-pilot.
The decision of the pilot to land on runway 06 with a tailwind, was in contradiction to company procedures
Part of runway 06 has a 1,75% downslope
The aircraft landed passed the normal touchdown zone
Evidence was found that the brakes were applied during the attempted take-off
The most probable cause was described as follows;
"the most probable cause of the accident as the inappropriate conduct of STOL procedure and landing technique carried out by the PIC, during landing phase and an endeavour to carry out take off again with no sufficient airspeed, no required lifting force and non-availability of required runway length to roll"
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