What happened
On 29 March 2025, a Uvify IFO multirotor was participating in a large-scale commercial swarm operation in Durham. The drone was part of a formation consisting of 540 unmanned aircraft flying within a circular area approximately 50 metres in diameter. A safety buffer, or sterile flight area, had been established extending 60 metres outward from the flight zone.
During the mission, the aircraft unexpectedly began to climb, departing from its programmed flight path. It reached an altitude of 196 metres, which placed it outside the pre-defined geofence. Upon breaching this boundary, the motors automatically ceased operation, causing the drone to fall. The aircraft eventually landed in a hedge located 50 metres beyond the perimeter of the sterile flight area. There were no injuries or damage reported.
The investigation
Following the incident, a joint investigation was conducted involving the operator, the developers of the control software, and the manufacturer of the aircraft. The inquiry focused on why the drone deviated from its altitude and flight path despite the geofence parameters.
Technical analysis established that vibrations occurring on the z-axis were a primary factor. It is believed that these vibrations, potentially caused by a worn motor, interfered with the aircraft's sensors. This led to inaccurate altitude and GNSS (Global Navigation Satellite System) estimations. The drone's onboard systems incorrectly processed this data as a descent, prompting the aircraft to increase thrust to compensate, which ultimately drove the drone upward out of the formation.
Findings
- Z-axis vibrations, likely stemming from a worn motor, caused erroneous sensor readings.
- The aircraft's software incorrectly interpreted the vibration-induced data as a loss of altitude.
- The resulting automated thrust increase caused the drone to climb beyond the permitted geofence height.