What happened
On the night of 28 February 2023, a DJI Mavic 2 Enterprise with registration ZT-YPH was conducting an aerial survey for a railway patrol near Paulpietersburg, KwaZulu-Natal. The operation was being performed under beyond visual line of sight (BVLOS) regulations. After completing several successful survey legs, the pilot began the return flight to the launch site. During this phase, the display screen on the remote controller suddenly went dark. Although the pilot attempted to trigger the return-to-home (RTH) function, the screen remained unresponsive. The pilot was eventually able to spot the aircraft's flashing lights as it descended toward the ground, but the drone could not be located at the immediate landing site. Following an extensive search, the aircraft was recovered 30 days later by security personnel in a different location, found to be undamaged.
The investigation
SACAA AIID examined the circumstances surrounding the loss of control and the subsequent recovery of the aircraft. The investigation focused on the status of the remote controller and the environmental conditions at the time of the incident. Investigators reviewed the operator's maintenance records, the pilot's credentials, and the technical specifications of the DJI Mavic 2 Enterprise. The investigation also looked into why the aircraft did not follow its programmed return path and why the pilot was unable to locate the drone immediately following its descent.
Findings
- The primary cause of the incident was the depletion of the remote controller unit's battery during flight, which led to a total loss of the control signal and a blacked-out display.
- Because the RTH function had been disabled, the RPA landed immediately upon the loss of connection.
- Adverse weather conditions, specifically winds that were noted as being unfavorable for flight, likely caused the batteries to drain more rapidly as the aircraft worked to maintain stability.
- The pilot misjudged the exact landing location of the aircraft, which led to the initial search being conducted in the wrong area.
- All necessary certifications, including the pilot's Remote Pilot Licence and the operator's Letter of Approval, were valid at the time of the occurrence.