What happened
On 30 May 2023, an Arace Sirin unmanned aircraft system, registered as ZT-XUR, was deployed for night-time security surveillance along the Zungwini railway lines near Vryheid, KwaZulu-Natal. The operation was being conducted under beyond visual line of sight (BVLOS) protocols.
Following a successful pre-flight inspection and a battery charge of 99%, the drone ascended to an altitude of approximately 1,321 feet AGL. Roughly twelve minutes into the mission, while positioned about 2.4 kilometres from the launch point, the aircraft experienced a loss of Command and Control (C2) connection with the remote pilot station. Although the system attempted to trigger its return-to-launch (RTL) function, the aircraft failed to return to the operator. The pilot eventually located the drone on the ground, where it had sustained substantial damage after striking a tree. The impact resulted in damage to the propellers, gimbal, landing gear, and arms.
The investigation
SACAA AIID investigators analyzed the post-accident log analysis report (LAR) and interviewed the pilot to reconstruct the flight path. The investigation established that approximately 11 minutes into the flight, the pilot executed a forward pitch and slight roll maneuver. This movement directed the aircraft toward a forested area, which subsequently caused the loss of the C2 link.
Additionally, the investigation reviewed the regulatory compliance of the flight. It was determined that the aircraft reached an altitude of 1,321 feet AGL, which significantly exceeded the 400ft AGL limit permitted for Class 3A UAS under CAR 2011 Part 101.01.5.
Findings
- The loss of connection between the ground control station and the aircraft occurred as the drone moved toward a forest.
- The pilot lost situational awareness regarding the terrain and potential hazards within the flight path.
- The flight altitude was in violation of established regulations for this class of unmanned aircraft.
- Weather conditions at the time of the incident were clear and did not contribute to the crash.