A ground mapping system that uses analog radar equipment to provide surveillance of aircraft and other surface vehicles on an airport surface. It is used by air-traffic controllers in airport control towers to monitor and control the movement of aircraft and vehicles. A situation display of the targets includes a map identifying the runways and taxiways and a visual map of the airport features, created through the contrast on the radar display resulting from the absence of returns from smooth concrete surfaces and the ground-clutter returns from grassy areas. An important safety function of the airport surface detection equipment (ASDE) is to determine whether or not a runway is clear for the next departure or arrival operation. The prevention of runway incursions by aircraft or by service vehicles has become more urgent because of several incidents since 2003. This runway clearance determination is aided by the ASDE's capability to display an image of the aircraft in which the target's extremities (nose, tails, and wing tips), especially for large aircraft, are evident to the eye.