What happened
On 9 July 2010, a Cessna 208B Grand Caravan, registration PK-RJS, was performing a charter flight from Wamena to Kobakma Airstrip in Papua, Indonesia. The flight, operated by PT. Ekspress Transportasi Antarbenua (Premi Air), carried one pilot and nine passengers.
Upon approaching Kobakma, the crew encountered fog and held for approximately 20 minutes. As visibility improved, the pilot proceeded with the approach. During the landing roll, the aircraft's left main wheel struck a muddy, gravel-filled area containing stones that had been placed there for a runway hardening project. This impact caused the aircraft to veer left, eventually striking a pile of stones alongside the runway. The aircraft sustained damage to its propeller blades, landing gear fairing, and a hole in the lower flap, which led to a fuel leak. There were no injuries among the ten people on board.
The investigation
The investigation focused on the aircraft's approach profile, the runway's surface condition, and the pilot's decision-making. Investigators examined the aircraft's touchdown point, which was approximately 450 meters from the start of Runway 09, leaving only 280 meters of remaining runway. The investigation also reviewed the presence of construction materials near the runway edge and the meteorological conditions, specifically the recent rainfall that had left the surface damp and muddy.
Findings
- The aircraft was on an unstable approach, characterized by a touchdown point that was too far down the runway and the activation of the stall warning horn.
- The pilot's decision-making was influenced by complacency.
- The aircraft veered off the runway because the left main tire experienced a higher deceleration rate than the right tire after hitting a muddy spot.
- The presence of stones for a runway improvement project created a hazard at the edge of the airstrip.
Safety action
The NTSC issued several recommendations, including the temporary cessation of flights to Kobakma until runway safety could be verified. Further recommendations addressed the need for improved operational analysis, the implementation of more robust Crew Resource Management (CRM) for Papua operations, and the necessity for the Director General of Civil Aviation to better identify and mitigate runway condition risks.