What happened
On 9 August 2011, a Piper PA28-180, registration ZS-FMV, departed Potchefstroom Aerodrome for a private flight intended for Wonderboom Aerodrome. While the flight began under visual meteorological conditions, the pilot encountered significant navigational difficulties shortly after takeoff.
Following a change in the planned route due to smoke from veld fires, the pilot relied on the aircraft's GPS for navigation. However, the pilot soon realized the aircraft was not reaching the intended turning point at Aviators Paradise. Attempts to troubleshoot the GPS and use VOR equipment were unsuccessful. Because the aircraft's transponder was non-functional, Johannesburg Information was unable to identify the aircraft's position on radar to provide assistance.
As fuel levels dropped and daylight faded, the pilot attempted to use a paper map to reorient, but could not determine his position. To avoid terrain in a mountainous area, the pilot executed a precautionary landing in an open, grass-covered field near Groblersdal. During the touchdown, the right main gear struck two hidden ant hills, causing the landing gear to detach and resulting in substantial damage to the right wing.
The investigation
SACAA AIID investigators examined the navigational equipment and flight planning processes. The investigation established that the aircraft and the pilot were properly certified and maintained. Crucially, the inquiry discovered that the GPS coordinates programmed for Aviators Paradise were incorrect; they actually pointed to Arnot Power Station, located approximately 110 nm away.
Investigators also found that while the pilot had prepared a thorough flight plan using a computer-based program the previous day, he chose to rely solely on the GPS on the day of the flight without verifying the programmed coordinates or maintaining a secondary navigation method.