History of the Flight
On 12 May 2007, a Piper Pawnee PA 25-235, registered PK-PNM and operated by PT Perkebunan Nusantara II (PTPN II), was conducting agricultural spray operations at the Klumpang tobacco plantation in Deli Serdang, North Sumatra, Indonesia. The aircraft had completed two earlier flights and landed for refueling and pesticide refilling. On the third flight, commencing at 09:30 local time (02:30 UTC), the aircraft was spraying areas 5 and 6, which contained 16 lines of trees. After spraying line 1, the aircraft climbed to 200 feet and initiated a right turn toward the next target on line 9. While passing through 150 feet during the climb, the pilot perceived a loss of power and a decrease in altitude. The pilot advanced the throttle to full in an attempt to recover power and altitude.
During the recovery climb, the aircraft was unable to avoid a cluster of bamboo trees. The aircraft struck the bamboo trees, lost control, and fell through the bamboo. The pilot shut down the engine before impact with the ground.
Injuries and Damage
The pilot, the sole occupant, sustained minor injuries. The aircraft was substantially damaged.
Meteorological Information
At the time of the accident, a witness—an aircraft maintenance engineer—reported that the wind was blowing extremely and sporadically from a direction of about 300 degrees. The plantation terrain was generally flat, but included bamboo, oil palm, and teak trees, as well as a river used for irrigation. The taller vegetation may have created turbulence when strong winds passed through.
Wreckage and Impact Information
The aircraft struck bamboo trees, resulting in substantial damage. Bamboo pieces were found in the engine cowling. The windshield was broken. The wing was affected by bamboo trees.
Cause
The investigation concluded that the aircraft experienced turbulence at low altitude and, uncontrolled, struck the bamboo trees, leading to the crash.
Safety Recommendations
As a result of the investigation, the National Transportation Safety Committee (NTSC) issued safety recommendations to improve agricultural operation safety and prevent similar occurrences.