Abstract: A flight processor that calculates a 4-dimensional trajectory having a sequence of two or more position, time and cost (x, y, z, t, c) tuples that minimize a defined cost. Some embodiments generate cost-optimized trajectories with simple or complex constraints and bounds such as fixed AGL altitude; minimum AGL altitude; maximum AGL altitude; minimum MSL; maximum MSL; avoidance of restricted airspace; adherence to non-restricted airspace such as easements; adherence to ground-based guideways, if applicable; and the constraint to maintain adequate radio frequency signal-to-noise needed for communications to the ground station or backhaul systems.