In air traffic control, an area control center (ACC), also known as a center or en-route center, is a facility responsible for controlling aircraft flying in the airspace of a given flight information region (FIR) at high altitudes between airport approaches and departures. In the US, such a center is referred to as an air route traffic control center (ARTCC).
A center typically accepts traffic from—and ultimately passes traffic to—the control of a terminal control center or another center. Most centers are operated by the national governments of the countries in which they are located. The general operations of centers worldwide, and the boundaries of the airspace each center controls, are governed by the International Civil Aviation Organization (ICAO).