What happened
On May 3, 2013, a Cessna 172 aircraft, registration PK-IUA, was performing a series of touch-and-go maneuvers at Nusawiru Airport in Pangandaran, Indonesia. The aircraft was operated by Bandung Pilot Academy and was being flown by a student pilot with 26 hours of experience on the type.
During the exercise, the aircraft touched down normally on runway 07. As the pilot applied power to transition into a takeoff roll, the aircraft suddenly veered to the left. Approximately 600 meters from the end of the runway, the aircraft crossed the runway shoulder and struck a concrete drainage structure. The impact caused the aircraft to come to rest in an upside-down position. While the student pilot was incapacitated by the impact, other students at the site provided immediate assistance before airport rescue teams arrived. The pilot sustained minor injuries.
The investigation
The investigation conducted by the NTSC focused on the aircraft's behavior during the application of power and the training standards of the flight academy. Investigators confirmed that the aircraft was airworthy, with no mechanical discrepancies or system failures recorded in the maintenance logs. The weather at the time was cloudy with 10 km visibility and calm winds.
Analysis of the aircraft's trajectory revealed that the sudden leftward movement was consistent with the aerodynamic effects of a spiraling slipstream. In single-engine propeller aircraft, increasing power creates a yawing moment that can pull the aircraft to one side, particularly at low speeds. The investigation also examined the flight school's qualification process, noting a lack of standardized limitations for solo flight competency.
Findings
- The primary cause of the excursion was the pilot's failure to anticipate the leftward yawing moment caused by the dynamic effects of increasing power.
- The student pilot had been released for their first solo flight after 24 total flight hours, following three check flights.
- The Bandung Pilot Academy lacked a formal policy regarding specific hour limitations or standardized criteria for solo flight qualifications.
- The aircraft's flaps were found in the full down position following the accident.