What happened
On the evening of 15 June 2023, a DJI Mavic 2 Enterprise Advanced (registration ZT-XSG) was conducting a night-time surveillance mission at the Bokgoni Colliery Mine in Mpumalanga. The flight was being operated under visual line of sight (VLOS) regulations as part of a permitted aerial patrol.
Approximately 13 minutes into the mission, the aircraft lost its command and control (C2) link while 1.5 kilometres away from the takeoff point. In response to the signal loss, the system initiated a Return-to-Home (RTH) procedure. As the drone approached the landing zone, it began an automated descent. During this phase, the aircraft struck a perimeter fence located near the pilot's station, causing the drone to flip upside down and strike the ground.
The impact resulted in minor damage to the aircraft, specifically affecting one landing gear and two propeller blades. There were no injuries and no damage to any ground property.
The investigation
SACAA AIID examined the flight logs and manufacturer data to reconstruct the sequence of events. The analysis of the post-accident log confirmed that the aircraft disconnected from the C2 link and transitioned to the Return-to-Home mode automatically.
While the pilot initially reported an attempt to manually intervene and climb to avoid the fence, the manufacturer's log analysis indicated that the pilot was engaged in completing flight documentation (the flight folio) while the aircraft was in its automated landing phase. This prevented the pilot from noticing the drone's trajectory toward the fence in time to prevent the collision.