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    Air Traffic Control (ATC)
    Experiments and Background Information

    ATC Research and Experiments

    Air Traffic Control


    Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air.


    The main job of ATC is to separate aircraft to prevent crashes and to make sure aircraft are running on time and as fast as possible. In some countries, ATC may also play a security or defense role (as in the United States), or actually be run entirely by the military (as in Brazil). Air traffic control was first introduced at London's Croydon Airport in 1921. Archie League, who controlled aircraft using colored flags at what is today Lambert-St. Louis International Airport, is often considered the first air traffic controller.

    Preventing crashes is done by what is called separation. This means that the aircraft are kept apart by a minimum distance at all times. Modern aircraft have crash detectors inside them that allows them to see the aircraft around them and stop crashing by flying away from each other. This system is a backup for if air traffic control is not available or if something goes wrong with air traffic control.

    Topics of Interest

    Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is:

    • to separate aircraft to prevent collisions
    • to organize and expedite the flow of traffic
    • to provide information and other support for pilots when able.

    In some countries, ATC may also play a security or defense role (as in the United States), or be run entirely by the military (as in Brazil).

    Preventing collisions is referred to as separation, which is a term used to prevent aircraft from coming too close to each other by use of lateral, vertical and longitudinal separation minima; many aircraft now have collision avoidance systems installed to act as a backup to ATC observation and instructions. In addition to its primary function, the ATC can provide additional services such as providing information to pilots, weather and navigation information and NOTAMs (NOtices To AirMen).

    In many countries, ATC services are provided throughout the majority of airspace, and its services are available to all users (private, military, and commercial). When controllers are responsible for separating some or all aircraft, such airspace is called "controlled airspace" in contrast to "uncontrolled airspace" where aircraft may fly without the use of the air traffic control system. Depending on the type of flight and the class of airspace, ATC may issue instructions that pilots are required to follow, or merely flight information (in some countries known as advisories) to assist pilots operating in the airspace. In all cases, however, the pilot in command has final responsibility for the safety of the flight, and may deviate from ATC instructions in an emergency.

    Although the native language for a region is normally used, English must be used on request, as required by the International Civil Aviation Organization (ICAO).

    A control tower, or more specifically an air traffic control tower, is the name of the airport building from which the air traffic control unit controls the movement of aircraft on and around the airport. Most of the world's airports are non-towered or mandatory frequency — only a minority of airports have enough traffic to justify a control tower, though some airports may open temporary tower units during special events like the Oshkosh Airshow.

    Air traffic controllers are the people who operate the air traffic control systems to expedite and maintain a safe and orderly flow of air traffic and help prevent mid-air collisions. They apply separation rules to keep aircraft apart from each other in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace. Because controllers have a very large responsibility while on duty, the ATC profession is often regarded as one of the most difficult jobs today and can be notoriously stressful, depending on many variables (equipment, configurations, weather, traffic volume, human factors, etc.).

    A Terminal Radar Approach Control (or TRACON) is an Air Traffic Control facility usually located within the vicinity of a large airport. Typically, the TRACON controls aircraft within a 30-50 nautical mile (56 to 93 km) radius of the airport between the surface and 10,000 to 15,000 feet (4,600 m). A TRACON is sometimes called Approach Control or Departure Control in radio transmissions. In the US Air Force it is known as RAPCON (Radar Approach Control), and in the US Navy as a "RATCF" (Radar Air Traffic Control Facility) In Canada, Approach Control may be called Arrival or Terminal.

    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).

    Air Traffic Flow Management (usually seen abbreviated as ATFM) is the regulation of air traffic in order to avoid exceeding airport or air traffic control capacity in handling traffic, and to ensure that available capacity is used efficiently.

    Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.

    Aviation light signals: An air traffic controller using a light gun that can be used to control aircraft with radio failure.In the case of a radio failure or aircraft not equipped with a radio, air traffic control may use a signal lamp to direct the aircraft. The signal lamp has a focused bright beam and is capable of emitting three different colors: red, white and green. These colors may be flashed or steady, and have different meanings to aircraft in flight or on the ground. Planes can acknowledge the instruction by wiggling their wings, moving the ailerons if on the ground, or by flashing their landing or navigation lights during hours of darkness.

    The air traffic control radar beacon system (ATCRBS) is a system used in air traffic control (ATC) to enhance surveillance radar monitoring and separation of air traffic. ATCRBS assists ATC surveillance radars by acquiring information about the aircraft being monitored, and providing this information to the radar controllers. The controllers can use the information to identify radar returns from aircraft (known as targets) and to distinguish those returns from ground clutter.

    The Professional Air Traffic Controllers Organization or PATCO was a United States trade union which operated from 1968 until its decertification in 1981 following a strike which was broken by the Reagan Administration. The 1981 strike and defeat of PATCO has been called "one of the most important events in late twentieth century U.S. labor history."

    Free flight is a developing air traffic control method that uses no centralized control (e.g. air traffic controllers). 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.

    Flight planning is the process of producing a flight plan to describe a proposed aircraft flight. It involves two safety-critical aspects: fuel calculation, to ensure that the aircraft can safely reach the destination, and compliance with air traffic control requirements, to minimise the risk of mid-air collision. In addition, planners normally wish to minimise flight cost by appropriate choice of route, height, and speed, and by loading the minimum necessary fuel on board.

    A flight progress strip is a small strip of paper used to track a flight in air traffic control (ATC). It may seem as an artifact of days gone by, however it is still used in modern ATC as a quick way to annotate a flight, to keep a legal record of the instructions that were issued, to allow others to see instantly what is happening and to pass this information to other controllers who go on to control the flight.

    Flight Traffic Mapping uses animation to depict flight traffic. The mapping of flights in real-time is based on a sophisticated air traffic control system that was developed for North America. The air traffic control system is a complex combination of electronics and people that helps guide planes from departure to destination. In 1991, data on the location of aircraft was made available by the Federal Aviation Administration to the airline industry. The National Business Aviation Association (NBAA), the General Aviation Manufacturers Association, the Aircraft Owners & Pilots Association, the Helicopter Association International, and the National Air Transportation Association petitioned the FAA to make ASDI information available on a "need-to-know" basis. Subsequently, NBAA advocated the broad-scale dissemination of flight traffic data. The Aircraft Situational Display to Industry (ASDI) system now conveys up-to-date information on flights to the airline industry and the public. Three companies distribute ASDI information, FlightExplorer, FlightView, and FlyteComm. Each company maintains a website that provides free updated information to the public on flight status and flight tracking. FlyteTrax, a product of FlyteComm, is a Windows-based program for displaying the geographic location of airborne IFR (Instrument Flight Rules) air traffic anywhere in the FAA air traffic system. Positions are reported for both commercial and general aviation traffic. The program can overlay air traffic with a wide selection of maps such as, geo-political boundaries, air traffic control center boundaries, high altitude jet routes, satellite cloud and radar imagery.

    Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License.)

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