The invention relates to the technical field of unmanned aerial vehicle design, in particular to an
energy planning-based fixed-wing unmanned aerial vehicle airline guidance method, which comprises the following steps of: after an engine of an unmanned aerial vehicle has a parking fault, acquiring a current optimal airline return path; combining the
energy consumption from the parking point to the FAF point and the glide
critical energy of the FAF point to judge whether the current energy of the unmanned aerial vehicle meets the requirement of idle glide returning; if the energy is sufficient, according to the real-time flight state parameters of the unmanned aerial vehicle, dynamically determining the transverse course
control mode of the unmanned aerial vehicle until the unmanned aerial vehicle enters air-slip glide guidance; controlling the longitudinal
control mode at the final idle slip gliding section of the idle slip returning field until grounding; if the energy is insufficient, the target point is switched to be the forced
landing point closest to the current position, and off-site forced landing is carried out; in the forced landing process, whether
excess energy exists or not is judged, and circling height descending is needed. According to the method, the unmanned aerial vehicle can accurately track an air-sliding
route and safely return to the field when energy is sufficient, and the unmanned aerial vehicle can be forced to land near a forced
landing point when energy is insufficient.