Five drones crashed into the River Thames near the London Eye during a practice session gone wrong, according to a report by the Accidents Investigation Branch (AAIB).
Incident during night-time rehearsal
The incident occurred on March 23 this year during a night-time rehearsal for a light show. Multiple unmanned aircraft systems (UAS) were flying in close formation when several experienced "degraded positional accuracy", the AAIB said.
As a result, two drones "descended out of control" early in the flight, and five others collided during a programmed transition and fell into the river. No injuries were reported, but the drones were never recovered.
Operator's findings and corrective measures
The operator determined that several drones had switched to a "low-accuracy positioning mode", causing them to drift within the swarm. Post-flight examination indicated that the Real-Time Kinematic (RTK) base station antenna, used to enhance drone position sensing, may have been partially obscured.
The operator reported that the RTK antenna height had subsequently been increased, with additional checks introduced to ensure an unobstructed signal and a stable RTK fix prior to flight.
