AAIB investigation to Uvify IFO, (UAS reg n/a)
Unreliable GPS position caused UAS to move out of defined geofence area, Durham, 29 March 2025
The unmanned aircraft (UA) was one of a swarm of 540 being flown within an area, about 50 m in diameter. A sterile flight area extended a further 60 m out in all directions.
During the flight, the UA began to climb, deviating from its intended flightpath to a height of 196 m, which was outside of the defined geofence. At this point, the motors automatically cut, and the UA fell to the ground, landing in a hedge 50 m beyond the sterile flight area boundary.
Investigations by the operator, UA control software developers and the UA manufacturer agreed that vibrations on the z-axis, possibly due a worn motor, led to incorrect GNSS and altitude estimations. The UA erroneously believed it was descending and so applied thrust to climb, resulting in it climbing out of formation with the other UAs.
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