Distance measuring equipment—often called DME—is one of the most valuable pieces of avionics in the aircraft. The main purpose of the DME is to display your distance from a VORTAC, VOR-DME, or localizer. (Some NDB stations have colocated DME, but not many.) DME reduces pilot workload by continuously showing your distance from the station, accurate to within a half-mile or three percent (and usually better). In addition, most DMEs display time-to-station and groundspeed.