A de Havilland Canada DHC-6 Twin Otter 300 was scheduled to operate a domestic flight in Papua New Guinea between Port Moresby-Jackson International Airport and several airports with a fuel stop at the Sasereme Airstrip.
The aircraft in its final position (© PNG AIC)
After an 11.40 local time departure from Port Moresby, the crew of two pilots and their 14 passengers settled in for the ~60-minute flight under Visual Flight Rules to the Sasereme Airstrip. The co-pilot was the pilot flying (pf) and the captain was the pilot monitoring (PM). It was the pf's first flight into Sasereme. During the flight, the company Operations Department informed the crew that it had rained during the last night at Sasereme, but currently, the weather was reported as fine. With this information, the crew discussed the upcoming approach and landing. Based on a wet, slippery runway and a landing weight of 5.300 kg the landing configuration was decided to be 30º Flaps, and a Final Approach Speed (Vref) of 73 knots. Getting close to the airstrip the weather was fine, sunny with few clouds and an estimated wind of 2-3 knots. The crew chose to land at strip 14 and joined the circuit, flying a left downwind.
The aircraft was flared at 50 feet and the aircraft floated in ground effect, when the aircraft touched down it bounced back in the air and touched down 20 meters later. At that point, the pic took over control and applied full reverse and right rudder to return the aircraft to the centreline. Right at that time, the left main wheel hit some potholes in the runway, degrading directional control.
Close up of the wing damage (© PNG AIC)
As it was deemed too late for a go-around the left engine was brought out of reverse while the right engine remained at full reverse.. The pic then applied the brakes in a cycling way (on-off-on-off). When the left main wheel hit a deeper pothole the aircraft pulled left sharply and left the airstrip. The left main landing gear partly separated from the fuselage and the left-wing impacted the ground. The aircraft came to a stop 5 meters from the strip. The pic shut the aircraft down while the co-pilot assisted the passengers in evacuating the aircraft.
The poor condition of the airstrip (© PNG AIC)
The accident was investigated by the Accident Investigation Commission of Papua New Guinea. The report as published by them is not accessible at the time of writing of this blog. Sources on the internet indicate that the investigation determined that the decision to operate into Sasereme on a scheduled air service, without knowing the serviceability of the strip, was a safety deficiency in the operation of the aircraft and a contributory factor in the accident.
The PIC did not provide the copilot with the opportunity to observe an approach and landing at Sasereme before allowing her to handle a landing there as pilot flying.
The PIC's late decision to take control of the aircraft from the copilot and execute a go-around was also a contributory factor.