We propose the he method of in-flight geometric calibration of a spacecraft imaging complex, which is engaged during remote sensing of the Earth. The essence of the method is the inclusion of the second approximation equations and the following comparison with another method, which uses two iterations of the first approximation. It is shown that if errors in setting the mutual orientation parameters do not exceed 10-20´, than acceptable calibration accuracy of the order of 10´´ ensures the first (linear) approximation of the developed method. Otherwise, the second approximation is performed. If the deviations of the setting of the parameters of mutual orientation are greater than 1°, we should be limited to the first approximation and conduct not one, but two iterations. The obtained results are confirmed by the statistical modelling.