The invention relates to a method of flying an unmanned aerial vehicle (UAV) in response to emergency conditions, the method including steps implemented using a controller forming part of the unmanned aerial vehicle, the steps comprising: defining a plurality of emergency conditions; associating each emergency condition with a priority level; associating each emergency condition with an objective; sensing a plurality of operating parameters of the unmanned aerial vehicle to detect whether one of the plurality of emergency conditions exists; when one or more emergency condition is detected: generating a trajectory for the detected emergency condition having a highest associated priority level, wherein the trajectory is generated in accordance with the objective associated with the emergency condition that has the highest associated priority level; and instructing the unmanned aerial vehicle to follow the generated trajectory.