What happened
On 10 March 2020, a Cessna 208B, registration PK-MAD, was performing an unscheduled cargo flight from Wamena to Angguruk Airstrip in Papua, Indonesia. The flight was conducted under Visual Flight Rules (VFR). To avoid cloud cover, the pilot climbed to an altitude of approximately 14,900 feet, necessitating the use of supplementary oxygen.
During the approach to Runway 09, the pilot observed that a section of grass extending from 30 meters before the threshold to 50 meters into the runway appeared brighter in color than the surrounding area. This was due to recent grass cutting. Because the visual distinction between this area and the actual runway was minimal, the pilot perceived the area before the threshold as a usable landing surface.
In an attempt to minimize the need for heavy braking, the pilot intended to touch down at the very start of the runway. However, the aircraft's power was reduced earlier than anticipated, and the aircraft descended lower than expected. The aircraft subsequently touched down approximately 22 meters before the runway threshold, veered left, and came to a stop 112 meters from the start of the runway. There were no injuries, but the aircraft sustained substantial damage.
The investigation
The investigation by the KNKT established that the aircraft was operating within weight and balance limitations and was equipped with STOL (Short Takeoff and Landing) and payload extension systems. The pilot, a highly experienced flight instructor with over 16,000 flying hours, was qualified for the operation.
Investigators found that the visual cues for the runway threshold were obscured because the freshly cut grass lacked contrast with the white threshold markers. Furthermore, the pilot's decision to land before the threshold was driven by a desire to reduce braking requirements, despite the operator's manual requirements.