What happened
On the morning of 7 December 2015, an Eclipse EA500, registration ZS-DKS, departed Lanseria International Airport (FALA) for Cape Town International Airport (FACT). The pilot, flying solo, initially maintained a cruising altitude of 36,000 feet and followed the filed flight plan. However, after passing the town of Douglas, the aircraft began to deviate significantly from its intended route, heading toward the OKTED waypoint, far east of its destination.
As the aircraft entered the FACA airspace, the pilot ceased all radio communication with air traffic control. This loss of contact prompted the declaration of an INCERFA, which was later escalated to a DETRESFA. During the period of silence, radar tracking showed the aircraft performing a series of increasingly complex and tight right-hand turns and orbits.
In an attempt to investigate the situation, a South African Air Force (SAAF) Gripen fighter jet was dispatched from Air Force Base Overberg. The military pilot intercepted the ZS-DKS just minutes before the impact. The Gripen pilot observed the aircraft flying in an extremely unstable manner and was unable to approach closely enough to determine the pilot's condition. The flight ended when the aircraft entered a left-wing low spiral dive, impacting terrain on the Spioenkop farm in the Overberg district. The pilot sustained fatal injuries, and the aircraft was destroyed.
The investigation
SACAA AIID investigators examined the wreckage and flight data to determine the cause of the deviation and subsequent crash. The investigation confirmed that the aircraft's engines were still delivering power at the moment of impact. While the aircraft's terrain warning system (EGPWS) recorded multiple alerts during a rapid descent, the investigation could not determine if the pilot was incapacitated due to the fatal nature of the injuries.
Technical analysis of the aircraft's components, including the air data computer and various digital storage media, yielded limited results regarding the specific cause of the flight path deviation. The investigation also noted that the aircraft had been well-maintained, with a valid certificate of airworthiness and no recorded mechanical defects prior to the flight.