Area Control Center
In air traffic control, an Area Control Center (ACC), also known as a Center (or in some cases, en-route, as opposed to TRACON control), is a facility responsible for controlling aircraft en route in a particular volume of airspace (a Flight Information Region) at high altitudes between airport approaches and departures. In the United States, 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 of 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 ICAO.
In some cases, the function of an Area Control Center and a Terminal Control Center are combined in a single facility. For example, NATS combines the London Terminal Control Centre (LTCC) and London Area Control Centre (LACC) in Swanwick in the UK.