What happened
On 26 February 2022, a Pilatus PC6/B2H4, registration PK-SNB, operated by PT Smart Cakrawala Aviation, was performing an unscheduled passenger flight between Nabire and Bayabiru in Papua, Indonesia. The day's schedule involved two round trips between Douw Aturure Airport and Bayabiru Airstrip, conducted under Visual Flight Rules (VFR).
Earlier that morning, the pilot completed a successful first leg. However, during that initial landing, the pilot noted that the runway surface was muddy and the soil was soft. Despite this observation, the pilot proceeded with a second flight carrying five passengers. During the landing approach to Runway 10 at Bayabiru, weather conditions were clear and winds were calm.
Upon touchdown, the aircraft veered to the left. In an attempt to maintain the centerline, the aircraft skidded, causing the left wing tip to strike bushes on the elevated ground adjacent to the runway strip. The momentum caused the aircraft to swing laterally, eventually leading the right wing and the nose to impact the higher ground on the left side of the runway. The aircraft came to a stop approximately 140 meters from the touchdown point. All occupants evacuated the aircraft without injury, though the aircraft sustained substantial damage.
The investigation
The KNKT investigation examined the aircraft's maintenance history, the pilot's experience, and the environmental conditions at the airstrip. The investigation included participation from the Swiss Transportation Safety Investigation Board as the state of manufacture.
Investigators reviewed flight data from the aircraft's GPS and APIBOX systems, which confirmed the aircraft's heading deviated significantly during the landing roll. The investigation also looked into the operator's existing risk assessments, which had previously identified the Bayabiru runway as a high-risk area for slippery conditions when wet, specifically recommending that flights only proceed when the runway is dry.
Findings
- The pilot was a qualified company instructor with significant experience in the region, though this specific route was relatively new to them.
- The aircraft was airworthy and operated within its weight and balance limits.
- Pre-flight information provided to the pilot indicated the runway might be wet due to previous rainfall, a condition the pilot deemed typical for the area.
- The pilot proceeded with the second flight despite having observed soft and muddy soil during the first landing, which contradicted the operator's established safety mitigation to ensure the runway was dry before operating.
- The aircraft's left wing and nose impacted higher ground located on the left side of the runway strip.
Safety action
- The KNKT has recommended that Smart Aviation strictly adhere to its own established hazard mitigation protocols, specifically ensuring that flight operations to Bayabiru do not proceed if the runway surface does not meet the required dry condition as identified in their risk assessments.