A seagull attacked a drone being used to perform a roof survey of Stranraer Academy in Scotland and caused the 6kg device to crash, according to official documents.
The unmanned aircraft system (UAS) had been launched manually by its pilot, who had completed all the normal pre-flight checks, before the autonomous flight mode was engaged, a report by the Air Accidents Investigation Branch (AAIB) said.
The DJI Matrice M200 drone, which is powered by four electric motors, was being flown in July this year when a black-headed gull suddenly flew over the drone pilot’s head and attacked the machine.
The 62-year-old pilot tried to regain manual control but the front right propellor of the machine was damaged, causing it to fall onto the roof of the building.
The pilot, who by that stage had racked up 95 hours flying drones, had previously operated the UAS in coastal and onshore areas where gulls were present and had been "cautious" in those areas, especially in the nesting season, the report said.
It added that “he had not experienced this level of aggression” before.