What happened
On the evening of 20 December 2022, a remote pilot was conducting an aerial surveillance mission at the Exxaro Leeuwpan Coal Mine in Mpumalanga. The operation, involving a DJI Mavic Enterprise with registration ZT-YIX, was being performed under beyond visual line of sight (BVLOS) regulations during night-time visual meteorological conditions.
Following a successful pre-flight inspection, the pilot launched the aircraft at 2118Z with a full battery. Approximately 19 minutes into the mission, the controller unit indicated that the battery power had reached a critically low level. In response to this depletion, the aircraft initiated an automated emergency landing procedure without pilot intervention. The drone descended into a nearby wetland roughly 450 metres from the launch site. Due to the location of the impact, the aircraft could not be recovered, and its condition remains unknown.
The investigation
The SACAA AIID investigation confirmed that the pilot held valid Remote Pilot Licence (RPL) endorsements for both VLOS and BVLOS operations, as well as a current medical certificate. The operator held the necessary operating certificates and approvals for the mission.
Regarding the aircraft, the DJI Mavic Enterprise had flown only 21.21 hours and had not yet reached its required periodic inspection interval. Investigators were unable to perform a post-accident log analysis because the wreckage was not located. The investigation also reviewed the operator's procedures regarding battery reserves, noting that regulations require a minimum 10% power reserve for both VLOS and BVLOS operations.
Findings
The investigation established that the critically low battery voltage triggered the aircraft's automatic emergency landing sequence, resulting in the loss of the drone. A significant contributing factor was that the aircraft was being operated with battery voltage levels below the minimum requirements established in the operator's standard operating procedures.