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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).
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, Hampshire.
The United States Federal Aviation Administration (FAA) 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). There are 22 ARTCCs 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 that 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.
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 aviation bands, using amplitude modulation (AM) 118 MHz to 137 MHz, for overland control) are published in aeronautical charts and manuals, and are also announced to a pilot by the previous controller during a hand-off. Most VHF radio assignments also have a UHF (225 to 380 MHz) paired frequency used for military flights.
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 center contact can be readily distinguished by their transponders. Pilots may request altitude adjustments or course changes for reasons including avoidance of 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.
Typically, centers have advance notice of a plane's arrival and intentions from its pre-filed flight plan.
Some centers have ICAO-designated responsibility for airspace located over an ocean such as ZNY and 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.
A center's control service for an oceanic flight information region may be operationally distinct from its service for one 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. Military aircraft, however, are typically installed with ARC-231 SATCOMs that allow over-the-horizon communication.
Area control centers (ACCs) control IFR air traffic in their flight information region (FIR).
The current list of FIRs and ACCs is maintained by the International Civil Aviation Organization (ICAO). as of October 2011 [update] :Note that the cited ICAO source gives the shapefile coordinates for each FIR, and also its page source gives a list of current ACCs in text form. The following is the alphabetic list of all ACCs and their FIRs
|ICAO code||Type||FIR or ACC||Oceanic or other subtype||Country or territory|
|AGGG||FIR||Honiara ACC||Solomon Islands|
|AYPM||FIR||Port Moresby ACC||Papua New Guinea|
|BGGL||FIR||Nuuk ACC||Greenland ( Denmark)|
|CZQM||FIR||Moncton Southern ACC||Canada|
|CZQX||FIR||Gander Domestic ACC||Canada|
|DIII||FIR||Abidjan ACC||Ivory Coast|
|EBBU||FIR||Brussels ACC||Belgium/ Luxembourg|
|EDYY||UIR||Maastricht ACC||Belgium/ Germany/ Netherlands|
|EGGX||FIR||Shanwick Oceanic OCA||Oceanic||United Kingdom|
|EGPX||FIR||Scottish ACC||United Kingdom|
|EGQQ||FIR||Scottish ACC (Mil)||Military||United Kingdom|
|EGTT||FIR||London ACC||United Kingdom|
|ENOB||FIR||Bodo Oceanic OCA||Oceanic||Norway|
|FABL||FIR||Bloemfontein ACC||South Africa|
|FACA||FIR||Cape Town ACC||South Africa|
|FACT||FIR||Cape Town ACC||South Africa|
|FADN||FIR||Durban ACC||South Africa|
|FAJO||FIR||Johannesburg Oceanic ACC||Oceanic||South Africa|
|FAJX||FIR||Johannesburg ACC||South Africa|
|FAPX||FIR||Port Elizabeth ACC||South Africa|
|FCCC||FIR||Brazzaville ACC||Congo, Republic of the|
|FZZA||FIR||Kinshasa ACC||Congo, Democratic Republic of the|
|GCCC||FIR||Canarias ACC||Canary Islands ( Spain)|
|GOOO||FIR||Dakar Oceanic ACC||Oceanic||Senegal|
|GVSC||FIR||Sal Oceanic ACC||Oceanic||Cape Verde|
|HAAA||FIR||Addis Ababa ACC||Ethiopia|
|HTDC||FIR||Dar es Salaam ACC||Tanzania|
|KZAB||FIR||Albuquerque ARTCC||United States|
|KZAK||FIR||Oakland Oceanic ARTCC||Oceanic||United States|
|KZAU||FIR||Chicago ARTCC||United States|
|KZBW||FIR||Boston ARTCC||United States|
|KZDC||FIR||Washington ARTCC||United States|
|KZDV||FIR||Denver ARTCC||United States|
|KZFW||FIR||Ft Worth ARTCC||United States|
|KZHU||FIR||Houston ARTCC||United States|
|KZID||FIR||Indianapolis ARTCC||United States|
|KZJX||FIR||Jacksonville ARTCC||United States|
|KZKC||FIR||Kansas City ARTCC||United States|
|KZLA||FIR||Los Angeles ARTCC||United States|
|KZLC||FIR||Salt Lake ARTCC||United States|
|KZMA||FIR||Miami ARTCC||United States|
|KZME||FIR||Memphis ARTCC||United States|
|KZMP||FIR||Minneapolis ARTCC||United States|
|KZNY||FIR||New York ARTCC||United States|
|KZOA||FIR||Oakland ARTCC||United States|
|KZOB||FIR||Cleveland ARTCC||United States|
|KZSE||FIR||Seattle ARTCC||United States|
|KZTL||FIR||Atlanta ARTCC||United States|
|KZWY||FIR||New York Oceanic ARTCC||Oceanic||United States|
|LKAA||FIR||Praha ACC||Czech Republic|
|LPPO||FIR||Santa Maria Oceanic ACC||Oceanic||Azores ( Portugal)|
|LQSB||FIR||Sarajevo ACC||Bosnia and Herzegovina|
|LWSS||FIR||Skopje ACC||North Macedonia|
|MDCS||FIR||Santo Domingo ACC||Dominican Republic|
|MHTG||FIR||Central American ACC||Honduras|
|MMFO||FIR||Mazatlan Oceanic ACC||Oceanic||Mexico|
|NTTT||FIR||Tahiti ACC||French Polynesia ( France)|
|NWWX||FIR||Nouméa ACC||New Caledonia ( France)|
|NZZC||FIR||New Zealand ACC||New Zealand|
|NZZO||FIR||Auckland Oceanic ACC||Oceanic||New Zealand|
|OEJD||FIR||Jeddah ACC||Saudi Arabia|
|OMAE||FIR||Emirates ACC||United Arab Emirates|
|PAZA||FIR||Anchorage ACC||United States|
|PAZN||FIR||Anchorage Oceanic ACC||Oceanic||United States|
|PHZH||FIR||Honolulu ACC||United States|
|RKRR||FIR||Incheon ACC||South Korea|
|SAVF||FIR||Comodoro Rivadavia ACC||Argentina|
|SAVU||UIR||Comodoro Rivadavia UIR||Argentina|
|SCCZ||FIR||Punta Arenas ACC||Chile|
|SCIZ||FIR||Easter Island ACC||Easter Island ( Chile)|
|SCTZ||FIR||Puerto Montt ACC||Chile|
|SLLF||FIR||La Paz ACC||Bolivia|
|SOOO||FIR||Rochambeau ACC||French Guiana ( France)|
|TJZS||FIR||San Juan ACC||Puerto Rico ( United States)|
|TNCF||FIR||Curaçao ACC||Curaçao ( Netherlands)|
|TTZP||FIR||Piarco ACC||Trinidad and Tobago|
|UEMH||FIR||Tyoply Klyuch ACC||Russia|
|UHMI||FIR||Mys Shmidta ACC||Russia|
|ULLL||FIR||Sankt Peterburg ACC||Russia|
|ULOL||FIR||Velikiye Luki ACC||Russia|
|USDK||FIR||Mys Kamenny ACC||Russia|
|VCCC||FIR||Colombo ACC||Sri Lanka|
|VDPF||FIR||Phnom Penh ACC||Cambodia|
|VHHK||FIR||Hong Kong ACC||Hong Kong|
|VVHM||FIR||Ho Chi Minh ACC||Vietnam|
|WAAZ||FIR||Ujung Pandang ACC||Indonesia|
|WBFC||FIR||Kota Kinabalu ACC||Brunei/ Malaysia|
|WMFC||FIR||Kuala Lumpur ACC||Malaysia|
|ZKKP||FIR||Pyongyang ACC||North Korea|
|ZMUB||FIR||Ulan Bator ACC||Mongolia|
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots. In some countries, ATC plays a security or defensive role, or is operated by the military.
Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control towers on the ground, they monitor the position, speed, and altitude of aircraft in their assigned airspace visually and by radar, and give directions to the pilots by radio. The position of air traffic controller is one that requires highly specialized knowledge, skills, and abilities. Controllers apply separation rules to keep aircraft at a safe distance from each other in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace, as well as on the ground. Because controllers have an incredibly large responsibility while on duty and make countless real-time decisions on a daily basis, the ATC profession is consistently regarded around the world as one of the most mentally challenging careers, and can be notoriously stressful depending on many variables. Many controllers, however, cite high salaries, and a large, unique, and privileged degree of autonomy as major advantages of their jobs.
Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as aerospace, which is the general term for Earth's atmosphere and the outer space in its vicinity.
Shanwick is the air traffic control (ATC) name given to the area of international airspace which lies above the northeast part of the Atlantic Ocean.
The world's navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the International Civil Aviation Organization (ICAO) and described below, though they might use only some of the classes defined below, and significantly alter the exact rules and requirements. Similarly, individual nations may also designate special use airspace (SUA) with further rules for reasons of national security or safety.
A flight information service (FIS) is a form of air traffic service which is available to any aircraft within a flight information region (FIR), as agreed internationally by ICAO.
The Australian Advanced Air Traffic System (TAAATS), is the hardware and software system used by Airservices Australia for air traffic control services. It is a paperless, computer-based system, which serves as an aid to civilian air traffic controllers. It does not control aircraft, but gives the user a display of information about an aircraft's position and associated information. It also handles communications and other information exchanges.
The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting. In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.
North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), is a structured set of transatlantic flight routes that stretch from the eastern North America to western Europe across the Atlantic Ocean, within the North Atlantic airspace region. They ensure that aircraft are separated over the ocean, where there is little radar coverage. These heavily travelled routes are used by aircraft flying between North America and Europe, operating between the altitudes of 29,000 and 41,000 ft inclusive. Entrance and movement along these tracks is controlled by special oceanic control centres to maintain separation between aircraft. The primary purpose of these routes is to allow air traffic control to effectively separate the aircraft. Because of the volume of NAT traffic, allowing aircraft to choose their own co-ordinates would make the ATC task far more complex. They are aligned in such a way as to minimize any head winds and maximize tail winds impact on the aircraft. This results in much more efficiency by reducing fuel burn and flight time. To make such efficiencies possible, the routes are created twice daily to take account of the shifting of the winds aloft and the principal traffic flow, eastward in North America evening and westward twelve hours later.
A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist in identifying them on air traffic control radar. Collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.
Controller–pilot data link communications (CPDLC), also referred to as controller pilot data link (CPDL), is a method by which air traffic controllers can communicate with pilots over a datalink system.
Boston Air Route Traffic Control Center is one of 22 Air Route Traffic Control Centers in the United States, located in Nashua, New Hampshire.
The Boston Consolidated TRACON (A90) is located in Merrimack, New Hampshire. A90 opened in 2004 after 8 years of development. The A90 function transferred to the new Boston Consolidated TRACON on February 22, 2004. The MHT function transferred over on March 7, 2004. Manchester TRACON used to be located at Manchester Airport below the old ATCT. Boston TRACON used to be located at the Logan International Airport Control Tower before being consolidated. The new facility is 63,000 square feet (5,900 m2). A Terminal Radar Approach Control, or TRACON, is responsible for descending airplanes from the ARTCC and lining them up for landing at their destination airport, as well as climbing departures before handing off to the ARTCC.
The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components shared jointly with the military. It is one of the most complex aviation systems in the world, and services air travel in the United States and over large portions of the world's oceans.
Montreal Area Control Centre is one of 7 Area Control Centres in Canada operated by Nav Canada. Montreal ACC is located in a building on the outskirts of Montréal–Pierre Elliott Trudeau International Airport.
Automatic Dependent Surveillance–Broadcast (ADS-B) is a surveillance technology and form of Electronic Conspicuity in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation. ADS-B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.
Anchorage Air Route Traffic Control Center (PAZA/ZAN) is located just outside the main gate of Joint Base Elmendorf-Richardson at 700 North Boniface Parkway in Anchorage, Alaska, United States. The Anchorage ARTCC is one of 22 Air Route Traffic Control Centers in the United States.
Toronto Area Control Center is one of seven area control centers in Canada operated by Nav Canada. The Toronto Area Control Centre is based near Toronto Pearson International Airport in Mississauga, Ontario.
Karachi Area Control Centre is one of two Area Control Centers in Pakistan operated by the Pakistan Civil Aviation Authority and is based in Terminal 1 at Jinnah International Airport in Karachi. Karachi ACC air traffic controllers provide en route and terminal control services to aircraft in the Karachi Flight Information Region. The Karachi FIR airspace covers Pakistani airspace between the 30° North to 23° North. To the north is the Lahore FIR. To the east is the Delhi FIR. To the south is the Muscat FIR and to the west are the Tehran FIR and Kabul FIRs.
Lahore Area Control Centre is one of two Area Control Centers in Pakistan operated by the Pakistan Civil Aviation Authority and based at Allama Iqbal International Airport in Lahore. Lahore ACC air traffic controllers provide en route and terminal control services to aircraft in the Lahore Flight Information Region (FIR). The Lahore FIR airspace covers Pakistani airspace between the 30° North to 37° North. To the south is the Karachi FIR. To the north is the Urumqi FIR. To the east is the Delhi FIR. To the west is the Kabul FIR.