What happened
On 16 May 2023, a large-scale flight test involving a swarm of 638 Uvify Ifo unmanned aircraft (UAs) took place near Norton St Phillip, Bath. The operation was intended to test a light display sequence. The initial takeoff and the programmed animation phase of the flight were executed successfully without any issues.
However, as the fleet transitioned into 'return to home' mode to revert to their designated grid positions, several drones drifted out of their intended formation. In response to this instability, the pilot issued an emergency hold command, which successfully caused the entire fleet to maintain their positions. Following this, a manual command was used to bring the drones back to their grid formation.
As the descent phase began, the same group of drones deviated from the formation once again. Due to growing concerns regarding battery endurance, the operator decided to land the swarm in order of altitude. While all aircraft remained within the established geofence, the incident resulted in significant damage to two UAs, including broken arms and chipped propellers.
The investigation
The operator conducted an internal investigation into the cause of the flight deviations. The inquiry focused on the hardware used to manage the swarm, specifically the controller units.
Findings
- The deviations from the programmed flight paths were caused by depleted batteries in the controller units.
- These batteries had been left in the switched-on position while the controllers were in storage, leading to unexpected power levels during the operation.