What happened
On 5 August 2012, a Cessna 172, registration PK-ROI, was conducting a mutual flight training exercise on a cross-country route. The flight, operated by PT Bali International Flight Academy, was traveling from Blimbingsari Airport back to Letnan Kolonel Wisnu Airport in Bali, Indonesia.
During the final approach to runway 32, the pilot reduced engine power to idle while positioned abeam a local landmark. This power reduction caused the aircraft to lose lift and enter a high sink rate. The aircraft struck the top of a tree approximately 10 meters high on short final. Following the initial impact, the pilot attempted a go-around by applying power; however, the aircraft veered left, striking an airport fence and another tree before coming to rest on the left side of the runway, roughly 59 meters from the centerline. The occupants of the aircraft sustained minor injuries, while the aircraft suffered substantial damage.
The investigation
The investigation conducted by the NTSC focused on the high sink rate observed during the short final approach. Investigators examined the aircraft's mechanical condition and found it was airworthy and all systems were operating normally prior to the accident.
The inquiry also scrutinized the training procedures provided by the flight academy. It was noted that student pilots had been taught to use specific visual landmarks, such as a local store, as triggers to reduce power. The investigation determined that the pilot's decision to reduce power to idle was based on his perception of the correct approach procedure taught by instructors. The investigators concluded that relying on visual landmarks for power reduction is unreliable, as proper approach performance should be based on maintaining the correct glide path angle.
Findings
- The flight was a mutual training exercise for student pilots.
- The aircraft was in an airworthy condition prior to the accident.
- The high sink rate following the reduction of engine power to idle led to the initial tree strike.
- The attempt to execute a go-array was unsuccessful due to asymmetric lift and the aircraft's movement after the first impact.
- The pilot's reliance on visual references for power reduction contributed to the loss of altitude.
Safety action
Following the accident, PT Bali International Flight Academy implemented several internal safety measures, including the temporary grounding of all student pilots for an evaluation of mutual flight policies. The academy also recommended that student pilots avoid flying after 10:00 AM during periods of fasting.