Accident
On the morning of 17 April 2009, a Pilatus PC-6/B2-H4 Turbo Porter aircraft, registered PK-LTJ, operated by PT. Mimika Air, departed on a charter flight from Ilaga to Mulia in the Puncak Jaya District of Papua. The aircraft was owned by the Mimika Local Government. On board were 11 people: one pilot, one observer, eight adult passengers, and one infant. The aircraft was also carrying National Government election boxes.
The flight was conducted under visual flight rules (VFR) with an estimated flight time of 18 minutes. No communication with the aircraft was recorded during the flight. Two minutes after the estimated time of arrival, when the aircraft had not arrived, a search was initiated.
Wreckage Discovery
On 18 April, search aircraft located the wreckage of the Porter at an elevation of approximately 12,000 feet on Mount Gergaji. The location was on the direct track between Ilaga and Mulia. The aircraft had impacted the ground in an inverted attitude and was destroyed by impact forces and a post-impact fire. All occupants were fatally injured.
Weather and Route
The weather in the valleys along the route was reported as mostly clear, with cloud cover on the mountains. The pilot flew the direct track, which passed over a mountain range. A high peak adjacent to and west of the track at about the midway point had an elevation of 13,700 feet.
Investigation Findings
The investigation determined that it was likely that the pilot had flown the aircraft into cloud and lost control of the aircraft in instrument meteorological conditions. The impact signature was consistent with uncontrolled flight at the time of impact. This probably resulted from the pilot becoming spatially disoriented after entering cloud.
Probable Cause
The official probable cause stated that the pilot may not have had adequate knowledge of the route and weather conditions, and may have been relying on Global Positioning System navigation. The pilot was attempting to climb on the direct track over Mount Gergaji. It was likely that the pilot became spatially disoriented after entering cloud while operating under visual flight procedures, leading to a loss of control and uncontrolled impact with terrain.