In air traffic control, an Area Control Center (ACC), also known as a Center, is a facility responsible for controlling instrument flight rules 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 world-wide, 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 such as a CERAP.
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 Center (ACC).
Subdivision of airspace into sectors
The Flight Information Region controlled by a Center may be further administratively subdivided into sectors
; each sector may use a distinct set of communications frequencies and personnel. An aircraft passing from one sector to another may be handed off and requested to change frequencies to contact the next sector controller. Sector boundaries are specified by an aeronautical chart
Air traffic controllers working within a Center communicate via radio with pilots of instrument flight rules aircraft passing through the Center's airspace. A Center's communication frequencies (typically in the very high frequency amplitude modulation aviation bands, 118 MHz to 137 MHz, for overland control) are published in aeronautical charts and manuals, and will also be announced to a pilot by the previous controller during a hand-off.
In addition to radios to communicate with aircraft, Center controllers have access to communication links with other Centers and TRACONs. In the United States, Centers are electronically linked through the National Airspace System, which allows nationwide coordination of traffic flow to manage congestion. Centers in the United States also have electronic access to nationwide radar data.
Controllers use radar to monitor the progress of flights and instruct aircraft to perform course adjustments as needed to maintain separation from other aircraft. Aircraft with which a Center has made radar contact can be readily distinguished by their transponders. Pilots may also request altitude adjustments or course changes to avoid turbulence or adverse weather conditions.
Controllers can assign routing relative to location fixes derived from latitude and longitude, or from radionavigation beacons such as VORs. See also Airway; VORs, Airways and the Enroute Structure.
Typically, Centers have advanced notice of a plane's arrival and intentions from its prefiled flight plan.
Oceanic air traffic control
Some Centers have ICAO-designated responsibility for airspace located over an ocean
such as ZOA, the majority of which is international airspace
. Because substantial volumes of oceanic airspace lie beyond the range of ground-based radars, oceanic airspace controllers have to estimate the position of an airplane from pilot reports and computer models (procedural control
), rather than observing the position directly (radar control
, also known as positive control
). Pilots flying over an ocean can determine their own positions accurately using the Global Positioning System
and can supply periodic updates to a Center. See also Air traffic control: Radar Coverage
A Center's control service for an oceanic FIR may be operationally distinct from its service for a domestic overland FIR over land, employing different communications frequencies, controllers, and a different ICAO code.
Pilots typically use high frequency radio instead of very high frequency radio to communicate with a Center when flying over the ocean, because of HF's relatively greater propagation over long distances.
ACCs by continent (incomplete)
The continental United States has twenty centers, which are operated by the Federal Aviation Administration
. The Centers are named after major cities, although most are physically located outside the cities for which they are named. Each Center is identified by a three-letter FAA identifier as well as a four-letter ICAO code
, which is the same as the FAA code prefixed by the continental United States' region code "K".
- Albuquerque Air Route Traffic Control Center (ZAB), 8000 Louisiana Boulevard N.E., Albuquerque, NM 87109
- Atlanta Air Route Traffic Control Center (ZTL), 299 Woolsey Road, Hampton, Georgia 30228
- Boston Air Route Traffic Control Center (ZBW), 35 Northeastern Boulevard, Nashua, New Hampshire 03060
- Chicago Air Route Traffic Control Center (ZAU), 619 Indian Trail Road, Aurora, Illinois 60506
- Cleveland Air Route Traffic Control Center (ZOB), 326 East Lorain Street, Oberlin, Ohio 44074
- Denver Air Route Traffic Control Center (ZDV), 2211 17th Avenue, Longmont, Colorado 80501
- Fort Worth Air Route Traffic Control Center (ZFW), 13800 FAA Road, Fort Worth, Texas 76155
- Houston Air Route Traffic Control Center (ZHU), 16600 John F. Kennedy Boulevard, Houston, Texas 77032
- Indianapolis Air Route Traffic Control Center (ZID), 1850 South Sigsbee Street, Indianapolis, Indiana 46241
- Jacksonville Air Route Traffic Control Center (ZJX), 811 East Second Street, Hilliard, Florida 32046
- Kansas City Air Route Traffic Control Center (ZKC), 250 South Rogers Road, Olathe, Kansas 66062
- Los Angeles Air Route Traffic Control Center (ZLA), 2555 East Avenue "P", Palmdale, California 93550
- Memphis Air Route Traffic Control Center (ZME), 3229 Democrat Road, Memphis, Tennessee 38118
- Miami Air Route Traffic Control Center (ZMA), 7500 N.W. 58th Street, uninc. Miami-Dade County, Florida 33166
- Minneapolis Air Route Traffic Control Center (ZMP), 512 Division Street, Farmington, Minnesota 55024
- New York Air Route Traffic Control Center (ZNY), 4205 Johnson Ave, Ronkonkoma, New York 11779
- Oakland Air Route Traffic Control Center (ZOA), 5125 Central Avenue, Fremont, California 94536
- Salt Lake City Air Route Traffic Control Center (ZLC), 2150 West 700 North, Salt Lake City, Utah 84116
- Seattle Air Route Traffic Control Center (ZSE), 3101 Auburn Way South, Auburn, Washington 98092
- Washington Air Route Traffic Control Center (ZDC), 825 East Market Street, Leesburg, Virginia 20176
The United States also operates Centers outside the contiguous United States:
- Anchorage Air Route Traffic Control Center (PAZA/ZAN), 5400 Davis Highway, Anchorage, Alaska 99506
- Honolulu Combined Center/RAPCON (CERAP) (PHZH/HCF), 760 Worchester Blvd, Honolulu, Hawaii
- San Juan CERAP (TJZS/ZSU), 5000 Carr. 190, Carolina, Puerto Rico
- Guam Air Route Traffic Control Center (PGZU/ZUA), 1775 Admiral Sherman Boulevard, Barrigada, Guam 96913
has seven Centers, which are operated by NAV CANADA
. The ICAO code for each Canadian Center is the same as its three-letter code prefixed by the Canadian country code "C".
- Edmonton Area Control Centre, Edmonton, Alberta (CZEG)
- Gander Area Control Centre, Gander, Newfoundland (CZQX) - Oceanic and domestic
- Moncton Area Control Centre, Riverview, New Brunswick (CZQM)
- Montreal Area Control Centre, Montreal, Quebec (CZUL)
- Toronto Area Control Centre, Toronto, Ontario (CZYZ)
- Vancouver Area Control Centre, Vancouver, British Columbia (CZVR)
- Winnipeg Area Control Centre, Winnipeg, Manitoba (CZWG)
- Mazatlan Center
- Mexico Center
- Monterrey Center
- Merida Center
- Eurocontrol (Maastricht Upper Area Control Centre, MUAC)
- Amsterdam, Netherlands
- Barcelona, Spain - AENA
- Berlin, Germany - DFS
- Bodø ATCC, Norway - Avinor
- Bordeaux, France
- Bratislava, Slovakia - LPS
- Brindisi, Italy - Enav
- Brest, France
- Brussels, Belgium, Belgocontrol
- Bucharest, Romania - Romatsa
- Copenhagen, Denmark - Naviair
- Ankara, Turkey - DMHI
- Istanbul, Turkey - DMHI
- Lisbon, Portugal - Nav Portugal
- London, England - National Air Traffic Services - NATS
- Madrid, Spain
- Marseille, France
- Milan, Italy - Enav
- Oslo ATCC, Norway - Avinor
- Padova, Italy - Enav
- Paris, France
- Reims, France - DSNA
- Rome, Italy - Enav
- Shannon, Republic of Ireland - Irish Aviation Authority
- Stavanger ATCC, Norway - Avinor
- Stockholm, Sweden - LFV Sweden
- Sofia, Bulgaria - ATSA Bulgaria
- Tallinn, Estonia - EANS
- Vienna, Austria - Austro Control
- Vilnius, Lithuania - Oro Navigacija Lithuania
- Warsaw, Poland - PATA
Split from an arc 45nm North of Sydney
to a line approximately to Port Hedland in Western Australia.
- Brisbane Air Traffic Services Center - YBBB, has responsibility for the northern portion and the Tasman Sea. Located at Brisbane Airport.
- Melbourne Air Traffic Services Center - YMMM, has responsibility for the southern portion including the Indian Ocean. Located at Melbourne Airport.
Two FIR's exist although they are both based in Christchurch.
- Christchurch Control - NZZC, has responsibility for the air traffic over New Zealand itself out to approximately 200nm.
- Auckland Radio - NZZO, has responsibility for the oceanic air traffic outside of the other FIR and includes half of the Tasman Sea stretching East to Samoa.