Abstract: A precise positioning method provides a 3D position data in the absence of GPS by correcting the INS error, which generates a precise altitude data in the presence of GPS by integrating the outputs of all the sources providing altitude data and which generates a precise position data by using the INS/GPS integrated system position data. The method is performed by processing the data from relative sensors in the platforms comprising INS which generates the data necessary for terrain-aided navigation, radar altimeter and barometric altimeter sensors, and DTED which is a database comprising the elevation above sea level of the relevant terrain.