What happened
On the morning of 24 April 2025, a Piper PA-3/6-375 Pawnee Brave, registered ZS-KHR, was performing agricultural spraying duties near Porterville Airstrip in the Western Cape. The flight, conducted under Part 137 regulations, involved applying insecticide to a citrus farm located roughly 20 kilometres north of the airfield.
After departing the gravel runway, the pilot transitioned to a cruising altitude of 1,000 feet to reach the target area. Upon arriving at the farm, which sits on the leeward side of a mountain, the pilot began the first spray run. During this maneuver, the aircraft encountered a sudden, powerful downdraft. This loss of lift caused the aircraft to descend into 30-foot-tall citrus trees, with the main wheels and spray boom striking the treetops. The impact caused the aircraft to pitch downward, leading to a ground impact. The pilot was able to exit the aircraft unassisted and escaped without injury, though the aircraft suffered substantial damage.
The investigation
SACAA AIID investigators reviewed the aircraft's technical records and the pilot's account of the event. The inspection confirmed that the Piper PA-36-375 Pawnee Brave was well-maintained, with the most recent 100-hour inspection completed approximately 31 flight hours prior to the accident. All required airworthiness directives and maintenance schedules were up to date. The pilot, an experienced commercial aviator with over 4,700 hours on this specific type, reported that the engine and all mechanical systems were fully functional and that no mechanical failures preceded the impact.
Findings
- The primary cause of the accident was the occurrence of mountain wave activity, which created a violent downdraft on the leeward side of the mountain.
- This atmospheric disturbance caused the aircraft to lose sufficient altitude to strike the citrus orchard canopy.