What happened
On 12 August 2015, a PAC-75 andXL aircraft, registration PK-KIG, was performing an unscheduled passenger flight from Wamena Airport to Ninia Airstrip in Papua, Indonesia. The flight was operated by PT. Komala Indonesia and carried one pilot, one engineer, and four passengers.
During the final approach at an altitude of approximately 6,500 feet, the aircraft's airspeed indicators malfunctioned, displaying zero airspeed. This failure triggered an aural stall warning. Video footage captured by a passenger showed the aircraft flying parallel to the runway on the left side before the pilot attempted a climb and left turn. This maneuver resulted in the aircraft stalling and impacting the ground roughly 200 meters southwest of the runway. The accident resulted in one fatality and several serious injuries.
The investigation
The KNKT investigation focused on the mechanical failure of the airspeed indicators and the pilot's subsequent response. Analysis of video footage confirmed that the airspeed indicators indicated zero during the approach. Investigators also examined the pilot's training records and the operator's safety management systems.
Technical review of the engine torque indicated that the power setting was insufficient to maintain flight during the recovery attempt. Furthermore, the investigation identified discrepancies in aerodrome information, noting that the recorded runway elevation in the aerodrome directory did not match the actual elevation at the crash site. The investigation also highlighted deficiencies in the operator's training programs, specifically regarding high-risk airstrip familiarization and procedures for managing unreliable airspeed.
Findings
- The decision to continue the flight with both airspeed indicators unserviceable significantly increased the pilot's workload, especially when approaching a high-risk aerodrome.
- The pilot performed an improper corrective action following the activation of the aural stall warning, executing a maneuver in an area insufficient for a safe recovery.
- A lack of familiarity with the specific requirements of the Ninia Airstrip led to an inappropriate escape maneuver that induced the stall.
- The pilot had not received adequate training or familiarization for operating at high-risk airstrips, nor had they been trained in Controlled Flight into Terrain (CFIT) or Approach and Landing Accident Reduction (ALAR) techniques.
Safety action
The KNKT issued several recommendations to PT. Komala Indonesia and the Directorate General of Civil Aviation (DGCA). Recommendations included improving pilot training for decision-making during abnormal conditions, ensuring proper airstrip familiarization, and implementing mandatory CFIT and ALAR training components within the regulatory framework. Additionally, the DGCA was advised to review aerodrome elevation data accuracy and establish regulations for pilot training regarding unreliable airspeed scenarios.