The algorithm to calculate the azimuth and the elevation angle on the source of radio emission in the topocentric system of coordinates is suggested according to the measurements done by the phase direction finder located on board a mobile object. The position of an aerial system direction finder to the earth topocentric system of coordinates can be changed. The change in the position of the aerial system influences the accuracy of calculating the bearings. The method to reduce the errors of bearing by iteration method is considered. The checking procedure of the algorithm by mathematical modelling is carried out.