Definition
A surface surveillance system used by air traffic controllers at busy airports to track the position and identity of aircraft and vehicles on runways and taxiways, and on approach within about five miles of the airport. ASDE-X combines surface radar, multilateration sensors, ADS-B, and data from the terminal radar to produce a single, continuously updated map of all movement on the airport surface, helping controllers prevent runway incursions and collisions, especially in low visibility or at night.
Plain English
A system that gives controllers a live picture of every aircraft and vehicle moving on the airport's runways and taxiways, so they can spot conflicts before they happen — even when they can't see the surface from the tower.
Context Anchor
Seen in discussions of advanced airport surface movement systems, airport surface safety, and operations at larger towered airports.
Derivation
The name describes the function: it 'detects' what's on the airport 'surface.' 'Model X' simply identifies this particular generation of the equipment, distinguishing it from earlier versions (ASDE-3 was the previous radar-only system). Knowing this helps the reader see ASDE-X as the modern, multi-sensor evolution of older ground radar.
Why Pilots Care
Reduces runway incursion risk by giving controllers immediate, accurate awareness of surface traffic.
Intuition Check
ASDE-X is not equipment the pilot normally operates in the cockpit. It is mainly airport and control tower equipment that helps controllers monitor ground traffic.
Example Sentence 1
At airports equipped with ASDE-X, controllers can see ground traffic clearly even when fog hides the runways from the tower.
Example Sentence 2
ASDE-X alerted the controller to a service vehicle that had entered an active taxiway.