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.

The United States Federal Aviation Administration defines an ARTCC as:

[a] facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace, principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.

An ARTCC is the U.S. equivalent of an Area Control Centre (ACC). There are twenty-two ARTCC's located in nineteen states.

The Flight Information Region controlled by a Center may be further administratively subdivided into Areas comprising two to nine sectors. Each Area is staffed by a set of controllers trained on all the sectors in that area.

Sectors use distinct radio frequencies for communication with aircraft. Each sector also has secure landline communications with adjacent sectors, approach controls, areas, ARTCCs, flight service centers, and military aviation control facilities. These landline communications are shared among all sectors who need them and are available on a first-come, first-served basis. Aircraft passing from one sector to another are handed off and requested to change frequencies to contact the next sector controller. Sector boundaries are specified by an aeronautical chart.

...
Wikipedia