Air Accidents Investigation Branch
Summary:
The UAS was being used in a police operation over an abandoned building near a public car park and train station. During hover over the building the aircrafts motors stopped and the aircraft fell vertically with no prior warning to the remote pilot. The aircraft struck the roof of the building and the battery separated. Recorded data indicated that the battery probably disconnected in flight. This could have been caused by the battery not having been fully latched prior to takeoff, or the latching mechanism or battery being worn from repeated use resulting in an in-flight disconnection. The operator has taken safety action to remind their pilots of the importance of pre-flight checks and checking airframe and battery condition at their base.