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 is to prevent collisions, organize and expedite the flow of traffic in the air, and provide information and other support for pilots.
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. Controllers apply separation rules to keep aircraft at a safe distance from each other and within proper airspace 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.
Free flight is a developing air traffic control method that uses no centralized control. Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade. Its potential impact on the operations of the national airspace system is disputed, however.
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.
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).
Procedural control is a method of providing air traffic control services without the use of radar. It is used in regions of the world, specifically sparsely populated land areas and oceans, where radar coverage is either prohibitively expensive or is simply not feasible. It also may be used at very low-traffic airports, or at other airports at night when the traffic levels may not justify staffing the radar control positions, or as a back-up system in the case of radar failure.
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.
The North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), are a structured set of transatlantic flight routes that stretch from 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 air traffic control (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.
In aviation, a non-towered airport is an airport without a control tower, or air traffic control (ATC) unit. In the United States, there are close to 20,000 non-towered airports compared to approximately 500 airports with control towers. Airports with a control tower without 24/7 ATC service follow non-towered airport procedures when the tower is closed but the airport remains open, for example at night.
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.
Standard instrument departure (SID) routes, also known as departure procedures (DP), are published flight procedures followed by aircraft on an IFR flight plan immediately after takeoff from an airport.
In air traffic control, separation is the name for the concept of keeping an aircraft outside a minimum distance from another aircraft to reduce the risk of those aircraft colliding, as well as prevent accidents due to secondary factors, such as wake turbulence. Separation can also apply to terrain, obstacles, and controlled airspace, wherein an aircraft must stay at a minimum distance from a block of airspace; as an example, all aircraft must be approved by the controller who "owns" the airspace before the aircraft is approved to enter that sector.
TRACON is a series of game software programs that simulate an air traffic control environment on a personal computer. The games were originally sold by Texas-based Wesson International as an offshoot to their line of professional air traffic control simulation products. TRACON and RAPCON were released in 1989, and TRACON II was released in 1990. Wesson was merged into Adacel in 2001.
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.
Gander Automated Air Traffic System (GAATS) is a proprietary system of Nav Canada used for the oceanic airspace of the Gander Area Control Centre (ACC).
The London Area Control Centre (LACC) is an air traffic control centre based at Swanwick near Fareham in Hampshire, southern England. It is operated by National Air Traffic Services (NATS), starting operations on 27 January 2002, and handles aircraft over much of England and Wales. The Swanwick facility replaces that of the former site at West Drayton.
Automatic Dependent Surveillance–Broadcast (ADS-B) is an aviation surveillance technology and form of electronic conspicuity in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts its position and other related data, enabling it to be tracked. The information can be received by air traffic control ground-based or satellite-based receivers as a replacement for secondary surveillance radar (SSR). Unlike SSR, ADS-B does not require an interrogation signal from the ground or from other aircraft to activate its transmissions. ADS-B can also receive point-to-point by other nearby equipped ADS-B equipped aircraft to provide traffic situational awareness and support self-separation.
