An Air Greenland DHC-8-200 suffered a runway excursion while landing on a runway with a lower than reported braking action coefficients, according to a preliminary report issued by the Accident Investigation Board Denmark.
On December 29, 2014, the DHC-8-200, OY-GRK, departed Godthåb/Nuuk Airport, Greenland on a commercial IFR domestic passenger flight to Paamiut (BGPT). The commander was the pilot flying and the first officer was the pilot monitoring.
En route to Paamiut, the flight crew got information on low braking action coefficients, which precluded a landing. For that reason, the flight crew decided to divert back to Godthåb/Nuuk Airport.
The flight crew got the following information on runway in use , weather and runway conditions at Nuuk: Runway in use was 02, the wind conditions were calm with a visibility of 3000 meters in light snow and a vertical visibility of 2000 feet. The temperature was – 2°C and the runway conditions were reported to be the same as when the flight departed Nuuk.
The flight crew decided to do a circling area navigation (RNAV) global navigation satellite system (GNSS) approach to runway 05. The aircraft circled west of the aerodrome for landing on runway 23. Before landing, the wind conditions were reported to be variable and 2 knots. The landing was done with a flap setting of 35°.
Upon landing on runway 23 and after having selected reverse on both engines, the flight crew experienced that the aircraft started to veer unexpectedly to the left.
The flight crew attempted to correct this by deactivating reverse on both engines, use of the wheel brakes, and nose wheel steering but the aircraft continued veering towards the left side of the runway.
The aircraft ran off the left side of the runway and came to a complete stop in the safety zone. There were no visible or noticeable damage to the aircraft and none of the persons on board sustained any injuries.
According to preliminary investigation results, there was a difference between the reported (measured at 13:40 hours) and effective (measured at 15:46 hours) braking action coefficients on runway 23 in combination with a momentary failure of the right hand power lever micro switch causing a momentary activation of the right hand propeller beta backup protection that deemed to have had a negative effect on the flight crew’s ability to maintain directional control, which resulted in the aircraft running off the side of the runway (runway excursion).
The AIB continues the technical and operational investigation.