What happened
On the evening of 12 January 2023, an ARACE Sirin remotely piloted aircraft, registered ZT-XOB, was performing an aerial surveillance mission at the AMSA Mine in Orkney, North West Province. The flight was being conducted under beyond visual line of and sight (BVLOS) regulations during night-time visual meteorological conditions.
After a successful pre-flight inspection, the pilot launched the aircraft with 99% battery power. Approximately 20 minutes into the mission, the aircraft lost connection with the control unit. In an attempt to recover the craft, the pilot activated the return-to-launch (RTL) function. However, the aircraft failed to reach the launch site. Upon reaching the last known coordinates, the pilot discovered the aircraft on the ground, where it had caught fire. The post-impact fire resulted in the total destruction of the aircraft. No injuries were reported during the incident.
The investigation
SACAA AIID investigators found that the aircraft's physical condition was severely compromised by the fire, which limited the examination of specific internal components. The investigation focused on the environmental conditions and the mechanical failure sequence.
Data indicated that the flight took place during significant weather instability, with winds recorded at 18 knots and gusting up to 26 knots. The investigation established that the control signal disconnection was triggered by an unexpectedly rapid depletion of the battery. This accelerated discharge was caused by the aircraft struggling to maintain flight against strong headwind conditions during the return maneuver.
Findings
- The primary cause of the crash was the loss of control signal due to rapid battery depletion caused by high wind resistance during the return-to-launch phase.
- The impact with the ground caused the battery pack casing to tear and the internal cell soldering to loosen.
- This mechanical failure led to internal short-circuiting between the battery cells, resulting in overheating and the subsequent fire.
- Meteorological reports at the time of the flight indicated weather conditions that were categorized as "not good to fly."