What happened
On 14 August 1999, a Perdeby Trike, registered ZS-WGN, was conducting a training flight near Ceres. The flight, which included an instructor and a student, departed from Ceres aerodrome at approximately 0600Z. The intended destination was a private runway located at the Weidekloof farm in the Koue Bokkeveld district, which had been prepared specifically for the training session.
During the approach to the farm's runway, an eyewitness observed the aircraft flying low over the strip in a westerly direction. The aircraft then executed a turn to the right, heading east. Following this, the aircraft attempted a sharp left turn toward the north. During this maneuver, the aircraft suddenly tumbled and struck the ground in a steep, nose-down attitude with the left wing low. There were two fatalities resulting from the impact.
The investigation
SACAA AIID investigators examined the flight path and the sequence of maneuvers leading up to the impact. The investigation focused on the aircraft's behavior during the final turns over the farm runway. Meteorological conditions at the time of the accident were reported as fine, suggesting that weather was not a contributing factor to the loss of control.
Findings
The investigation established that the accident was caused by a loss of airspeed leading to an aerodynamic stall. Specifically, the pilot reduced engine power while performing a steep turn, which caused the aircraft to stall. The pilot was unable to recover the aircraft from this state before it struck the terrain.