What happened
On 28 January 2010, an Antonov AN-26B, registration 4L-IFE, was performing an unscheduled cargo flight from Sentani Airport to Wamena Airport in Papua, Indonesia. The flight, operated by PT. Manung and crewed by two pilots and one flight engineer, arrived at Wamena at 03:51 UTC. During the landing roll on runway 15, the pilot in command was unable to stop the aircraft before it exited the paved surface. The aircraft eventually came to a rest in a ditch approximately 200 meters beyond the end of the runway. While there were no injuries to the three crew members, the aircraft sustained significant damage to the nose landing gear, the right propeller blades, the right wing tip, and the lower fuselage. The impact also damaged the airport's perimeter fence.
The investigation
The investigation focused on the operational parameters of the flight and the accuracy of the crew's performance calculations. Investigators examined the aircraft's weight and balance documentation and the landing performance sheets used by the crew. A critical discrepancy was identified regarding the aerodrome elevation; the crew utilized an outdated elevation of 5,084 feet for their calculations, failing to account for a NOTAM that had increased the official elevation to 5,430 feet. Additionally, the investigation is looking into the regulatory framework of the aircraft's operation, as the 4L-IFE was being operated under a special permit rather than being listed on the operator's primary Air Operator's Certificate.
Safety action
Following the incident, the NTSC issued several recommendations to the Directorate General of Civil Aviation (DGCA) and the operator. The DGCA is urged to review the procedures for granting flight approvals to operators using aircraft not listed on their approved certificates. Furthermore, the NTSC recommended a review of the operational specifications for the Antonov AN-26B type within Indonesia, specifically regarding operations in the Papua region. PT. Manunggal Air Service was also advised to review its internal procedures for managing aircraft operated under special permits to ensure all technical and safety requirements are strictly maintained.