Described embodiments include apparatus for operating an unmanned aerial vehicle (UAV). The apparatus includes a receiver, a transmitter, and a processor. The processor is configured to receive, via the receiver, coordinates of a position sensor coupled to a portion of a crane, a configuration of the crane changing over time due at least to movement of the portion of the crane relative to a tower of the crane, to compute, in response to the received coordinates, a flight path that passes under a boom of the crane while circumventing the crane, and to cause the UAV to follow the computed flight path, by transmitting flight instructions, via the transmitter, to the UAV. Other embodiments are also described.