What happened
On the evening of 29 June 2023, an Arace Sirin unmanned aircraft system, registered as ZT-XXM, was performing an aerial survey at the Sasol Syferfontein Mine near Secunda, Mpumalanga. The operation was being conducted under beyond visual line of sight (BVLOS) regulations.
Following a successful pre-flight inspection, the pilot launched the aircraft at 1719Z. The UAS climbed to approximately 120 feet above ground level to perform post-takeoff checks while in a hover. During this phase, the display on the remote pilot station began to flicker intermittently before turning off entirely. When the screen eventually rebooted, it displayed a "GPS glitch error" message. In an attempt to land the aircraft safely, the pilot initiated a slow descent, but the UAS instead entered an uncontrolled, rapid descent, resulting in a crash. The impact caused substantial damage to the aircraft's propellers, camera, and landing gear. No injuries to persons on the ground were reported.
The investigation
SACAA AIID examined the operational and regulatory status of the flight and the equipment. The investigation confirmed that the pilot held a valid Remote Pilot Licence with the necessary BVLOS rating and a current medical certificate. The UAS was operating under a valid Letter of Approval and had undergone a mandatory periodic inspection less than a month prior to the accident. Additionally, the operator held a valid Remote UAS Operating Certificate, and the maintenance technician involved in the previous inspection was properly licensed.
Findings
The investigation established that the primary cause of the accident was an interrupted display on the remote pilot station screen, which led to a loss of control. A contributing factor to the crash was an incorrect disarming procedure.