What happened
On 12 September 2012, a Thrush 34T, registration PK-PNO, operated by PT Sinar Mas Super Air for agricultural purposes, departed Ujung Tanjung Airstrip for Nagamas Airstrip. During the flight, the pilot encountered low cloud cover along the route. Upon reaching Nagamas, the runway was not visible due to haze, prompting the pilot to return to the departure airfield.
While approaching Ujung Tanjung, the pilot noted wind conditions between 7 and 10 knots from the southeast and observed motorcycles traveling along the edge of the runway. During the landing sequence, the aircraft experienced a hard landing and bounced. As the aircraft continued its roll, it veered to the left and exited the runway, coming to rest in a ditch approximately 21 meters from the runway edge beneath palm trees. The aircraft ended up with its tail inverted. The impact caused the right landing gear to collapse and bend rearward, resulting in dented wing structures and bent propeller blades. There were no injuries reported.
The investigation
The investigation focused on the environmental conditions and the operational circumstances surrounding the landing. Investigators examined the weather patterns in Sumatra during September, noting that the Inter Tropical Convergence Zone (ITCZ) typically brings increased moisture and cloud formation to the region during this period.
Technical examinations confirmed that the aircraft and its systems were airworthy and functioning normally prior to the impact. However, the investigation identified that the runway surface, consisting of grass, was slippery when wet. Furthermore, a crossing road near the middle of the runway featured a significant joggle of over five centimeters, and the presence of vehicles near the runway shoulder added complexity to the landing environment.
Findings
- The pilot performed the flight without accessing proper or reliable weather information, leading to an encounter with low clouds that complicated VFR operations.
- The pilot's workload was significantly increased by the combination of marginal weather conditions and active hazards near the runway edge.
- There was a lack of documented hazard identification and risk assessment as required by the operator's Aircraft Operation Manual (AOM).
Safety action
Following the investigation, the NTSC issued safety recommendations to PT Sinar Mas Super Air, emphasizing the need for pilots to utilize correct weather resources for VFR flights and for management to strengthen hazard and risk assessment protocols. Recommendations were also directed to the Directorate General of Civil Aviation (DGCA) to ensure these safety improvements are implemented.