Introduction
On 17 January 2013, a Pilatus Porter PC-6/B2-H4 aircraft, registered PK-UCJ, operated by Yayasan Jasa Aviasi Indonesia (YAJASI) as a non-scheduled cargo flight, experienced a runway excursion during landing at Wamena Airport in Wamena, Papua, Indonesia.
Flight History
The flight departed from Sentani Airport, Jayapura, Papua at 06:54 local time (21:54 UTC on 16 January 2013). On board were two pilots: the left-seat pilot, under training as second in command (SIC) and acting as pilot flying, and the right-seat instructor acting as pilot in command (PIC) and pilot monitoring. The flight to Wamena proceeded normally with no indications of any malfunction.
Weather at Wamena was visual meteorological conditions with calm wind. The runway was slippery due to water and rubber deposit contamination; rain had stopped 20 minutes before the occurrence.
The aircraft touched down on runway 15 at 08:01 local time on the centerline. The pilot flying applied reverse thrust, and the aircraft began to veer to the right. The pilot flying attempted to recover by pushing left rudder followed by left brake, but there was no response and the aircraft continued veering right.
Just before exiting the runway, the SIC applied full reverse. The PIC instructed to add power to improve rudder effectiveness and then took over the controls. The PIC moved the power control lever forward in an attempt to straighten the aircraft.
Approximately 157 meters from the first touchdown point, the aircraft exited the right side of the runway and continued rolling over the runway shoulder for about 15 meters parallel to the runway. The aircraft struck taxiway marking Alpha, causing the horizontal stabilizer, left wing tip, and left aileron to detach from the wing. The aircraft became airborne again at a distance of 315 meters from touchdown and continued rolling until approximately 408 meters from the first touchdown, where it re-entered the runway. The aircraft then taxied to the YAJASI apron and parked.
Injuries and Damage
No persons on board were injured. The aircraft sustained major damage.
Contributing Factors
The investigation concluded that there was no approach and landing briefing that considered the effect of reverse power on wet runway conditions. The pilot flying applied full left rudder followed by left brake, which had reduced the capability of the tires to corner. In combination with the slippery runway, this generated much more cornering (lateral) force and the aircraft might mor.