A plan view of a launch site with a parked vehicle and a reinforced concrete pad. A drone is set down on the concrete beside the vehicle. A heading dial on the right shows two arrows: where the drone's nose really points, and where its compass says it points. Near the vehicle and concrete the two disagree. The drone is spun for a compass calibration, but afterwards the arrows still disagree: calibration does not fix a bad launch location. The drone is then carried away to open ground, and the compass heading and nose direction agree. The size of the error is schematic.
