Definition
A short-range, high-resolution radar system used by air traffic controllers to monitor the position of aircraft and ground vehicles on airport runways and taxiways, particularly during periods of low visibility such as fog, heavy rain, or darkness.
Plain English
A special radar that lets the tower see exactly where every plane and vehicle is on the ground, even when the controller can't see them out the window.
Context Anchor
Seen in instrument flying, tower operations, ground control, and low-visibility airport movement discussions.
Derivation
The name describes its job in plain terms: equipment that detects what is on the airport surface. It is called surface detection (rather than just radar) because it watches the ground, not the sky.
Why Pilots Care
Reduces the chance of runway incursions by giving controllers an accurate picture of ground traffic even when visibility is poor.
Analogy
It is like giving the tower a live map of the airport ground area, showing where airplanes and vehicles are instead of relying only on looking out the window.
Intuition Check
Do not read “surface detection” as detecting runway condition, such as ice or water. Here it means detecting aircraft, vehicles, and airport features on the ground surface.
Example Sentence 1
During the dense fog, the controller relied on ASDE to track our taxi route from the gate to the runway.
Example Sentence 2
During the low-visibility taxi, the controller issued instructions based on data from the airport surface detection equipment.