Definition
A long-range air traffic control radar used by Air Route Traffic Control Centers (ARTCCs) to detect and track aircraft flying along en route airways and high-altitude routes between terminal areas. It provides controllers with the position and movement of aircraft over wide geographic regions, supporting separation and traffic management during the cruise phase of flight.
Plain English
A big, long-range radar that watches airplanes while they are cruising between airports, so controllers can see where everyone is and keep them safely apart.
Context Anchor
You may see RSR in FAA acronym lists, air traffic control discussions, and material about radar coverage away from the immediate airport area.
Derivation
‘En route’ is from French, meaning ‘on the way.’ ‘Surveillance’ comes from the French ‘surveiller,’ to watch over. So the name literally describes what the radar does: it watches over aircraft while they are on the way between places.
Why Pilots Care
Gives controllers the information needed to keep aircraft safely separated and on course during long flights.
Intuition Check
Do not read “surveillance” as personal monitoring or enforcement. Here it means radar watching for aircraft positions so air traffic control can track traffic safely.
Example Sentence 1
Once the flight leveled off at cruise altitude, the controller tracked it on en route surveillance radar all the way across the center’s airspace.
Example Sentence 2
En route surveillance radar coverage allows continuous tracking across most of the country.