What happened
On the night of 11 June 2023, an Arace Sirin UAS, registered ZT-YOS, was conducting a night-time security surveillance mission at the Karan Beef Farm in Nigel, Gauteng. The flight was being operated under Beyond Visual Line of Or Sight (BVLOS) regulations.
During the fifth flight of the evening, the aircraft ascended to a height of approximately 6.3 feet. Upon attempting to transition flight modes, the drone became unresponsive to pilot inputs and entered an uncontrolled spin. The aircraft subsequently drifted into a tree located roughly 10 metres from the launch site, resulting in substantial damage to a propeller and one landing gear. No injuries were reported on the ground.
The investigation
SACAA AIID investigators examined the flight logs and aircraft maintenance history. The investigation confirmed that the aircraft had a high-quality satellite connection, with over 20 satellites in view at the time of the incident. Records also indicated that the aircraft's GPS had experienced a malfunction and had been repaired just two days prior to the accident.
Analysis of the flight data revealed that the pilot attempted to use "Auto" mode, but the aircraft rejected the command. The pilot then switched to "Loiter" mode to initiate takeoff. While in this mode, the aircraft failed to maintain its position and drifted toward the nearby tree.
Findings
- The pilot failed to perform a proper pre-flight check or select a starting waypoint before launch.
- The aircraft was incorrectly configured for the flight parameters.
- The pilot engaged "Loiter" mode without ensuring the aircraft was stabilized or correctly programmed for the intended mission path.