What happened
On 5 April 2002, a PIPER PA-28-140, registered ZS-EBM, was conducting a private aerial patrol for stock theft in the Giant’s Castle area of the Drakensbard. The flight departed from Estcourt aerodrome at 0420Z with a passenger on board.
While flying in a westerly direction, the aircraft followed a valley at an altitude of roughly 6800 ft. As the pilot attempted to execute a left-hand turn to move away from the mountain range and return down the valley, the aircraft encountered a powerful downdraught. This sudden loss of altitude caused the aircraft to strike the eastern side of the mountain during the shallow turn. The impact resulted in substantial damage to the aircraft, though both the pilot and the passenger survived with minor injuries. They were subsequently evacuated to a hospital in Pietermaritzburg via a SANDF helicopter.
The investigation
SACAA AIID investigators examined the flight path and meteorological conditions at the time of the accident. The investigation established that the aircraft was operating in the lee of a mountain range. The terrain at the site of the impact was at an elevation of 6000 ft, and the aircraft had been maintaining an altitude of approximately 6800 ft prior to the encounter with the downdraught.
Findings
- The pilot was maneuvering near the lee side of a mountain range with limited terrain clearance.
- The aircraft was in the process of a shallow banked turn to avoid the mountain when it encountered a strong downdraught.
- The downward force of the air current caused the aircraft to descend into the rising terrain.