A method of operating a terminal device supporting a plurality of positioning techniques which use positioning measurements made by the terminal device and positioning assistance information received from a location server to determine the location of the terminal device. The method includes: establishing a target location; selecting a first positioning technique for navigating towards the target location; receiving first positioning assistance information from the location server for the first positioning technique; determining a first location of the terminal device in accordance with the first positioning technique and the first positioning assistance information; establishing a first trigger for using a second positioning technique which is associated with higher positioning accuracy than the first positioning technique; and, in response to determining the first trigger is satisfied, determining a second location of the terminal device in accordance with the second positioning technique and second positioning assistance information received from the location server.