Abstract: The compensation of aircraft's magnetic field interference is a key technology in aeromagnetic survey. For the flight learning problem of unmanned aircrafts, Tolles-Lawson model is improved with the consideration of geomagnetic gradient, a fold line flight method is proposed, and the different flight paths are discussed. The parameters calculated using the proposed fold line flight method have a good result in aeromagnetic compensation according to simulated and real flight data. And increase in numbers of courses is helpful for obtaining more precise parameters with the method. If learning courses are more orthogonal to each other in the condition of same numbers of courses, the calculated parameters is more precise as well.

Key words: geodesy, geomagnetic survey, geomagnetic gradient, fold flight path, number of courses, magnetic compensation