Air traffic control

Air traffic control (ATC) is a service provided by ground-based air traffic controllers. These controllers help guide airplanes when they are on the ground and while they are flying through special areas called controlled airspace. Their main job is to keep airplanes safe by making sure they stay far enough apart to avoid crashes. They also help organize the flow of airplanes so that flights can move quickly and smoothly.

Controllers watch the location of airplanes using special tools called radar and talk to the people flying the planes using radio. They give instructions to pilots to keep airplanes separated by a safe distance. These instructions must be followed, but the pilot of the airplane always has the final say about the safety of their flight. If there is an emergency, a pilot can ignore the instructions if it means keeping the airplane safe.

Weather can sometimes make air traffic control more difficult. Things like thunderstorms, strong winds, and poor visibility can cause delays, make planes fly different routes, or even force airplanes to land at different airports. ATC works with all kinds of airplanes, including private, military, and big commercial jets. Whether the airplane is small or large, ATC helps keep everyone in the sky safe and moving efficiently.

Language

Air traffic control uses either English or the local language spoken where the control station is located. This is required by the International Civil Aviation Organization. Usually, the local language is used, but controllers must switch to English if asked.

See also: Aeronautical phraseology and Aviation English

History

In 1920, Croydon Airport near London, England, became the first airport in the world to use air traffic control. The control tower was a small wooden hut with windows on all sides. It gave pilots basic information about traffic, weather, and their location.

In the United States, air traffic control grew in three main ways. After World War I, the U.S. Post Office started using military methods to guide reconnaissance aircraft, which later became flight service stations. The first control tower at an airport opened in Cleveland in 1930. With the invention of radar in the 1950s, new facilities were added to help manage busy airport areas. The first center to direct airplanes between airports opened in Newark in 1935, followed by centers in Chicago and Cleveland.

Airport traffic control tower

The main way to manage the area around an airport is by watching from a tall control tower. This tower, usually with many windows, sits on the airport grounds. People called air traffic controllers, often just called controllers, help planes and vehicles move safely on the roads and runways of the airport. They also help planes in the sky close to the airport, usually within 5 to 10 nautical miles (9 to 19 kilometres; 6 to 12 miles), depending on the airport’s rules. Controllers follow specific rules but also need to make quick changes when needed, which can be stressful.

Some airports use a remote and virtual tower (RVT) system, where controllers work from a place far from the airport but still help guide the planes.

Ground control looks after the areas where planes move on the ground at the airport.

Air control, also called tower control by pilots, looks after the runways where planes take off and land.

Clearance delivery is where controllers give planes instructions about their flight path before the planes start moving.

In supply chain management, the idea of a “supply chain control tower” is used to describe a system that gives a clear view of the whole supply chain, much like an air traffic control tower. A writer for Gartner says this can be done by using people, processes, data, and technology to make better decisions.

Airports without a control tower (mandatory frequency airport)

Some airports do not have a control tower but still need pilots to talk on a special radio frequency. These are called mandatory frequency airports. They are rare in the United States, but common in places like Canada, Australia, the United Kingdom, and Norway. Often, these airports have regular flights but not enough traffic to need a control tower.

At these airports, a flight service specialist might give pilots information about other planes, weather, and conditions on the ground. They can pass along some instructions from air traffic controllers but cannot give clearances themselves. In the United Kingdom, these airports use a service called Air/Ground Radio, with the callsign ending in "Radio". Examples in Canada include Kingston/Norman Rogers Airport and Kuujjuaq Airport.

Approach and terminal control

"TRACON" and "Approach control" redirect here. For the video game series, see TRACON (series). For the railway signalling setup, see UK railway signalling § Approach release.

See also: Terminal control area

In the U.S., TRACONs are additionally designated by a three-digit alphanumeric code. For example, the Chicago TRACON is designated C90.

Area control centre / en-route centre

Main article: Area control center

An area control center is a special kind of air traffic control center. It mainly helps planes that are flying high up and using instruments, instead of planes that are landing or taking off. Each of these centers looks after a certain area called a flight information region. Some of them also watch planes flying over the ocean. They do similar work to other air traffic control centers, like changing a plane’s path if there is bad weather and making sure planes stay far apart.

Radar coverage

The position of aircraft is mainly determined by different types of radars. These include en-route radar that covers up to 240 NM (460 km), airport surveillance radar that covers up to 52 NM (96 km) of the airport below an elevation of 25,000 feet, surface movement radar that covers the airport surface within 2 NM (3.7 km), and secondary surveillance radar that works within line-of-sight range.

To extend their abilities, some air traffic services have implemented automatic dependent surveillance – broadcast (ADS-B). This newer technology works differently from radar. Instead of radar finding an aircraft, the ADS-B equipped aircraft sends out a position report using its onboard navigation equipment. There is also ADS-C, where the aircraft sends position reports at set time intervals, either automatically or when the pilot initiates it. Controllers can ask for more frequent reports in special situations, but this is not common because of costs, except during emergencies. ADS-C is especially useful over water where radar systems cannot be placed. Operational display systems now use ADS-C inputs as part of their displays.

A radar archive system keeps electronic records of all radar information for a few weeks. This can help with search and rescue when an aircraft disappears from radar, allowing controllers to review the last radar returns to estimate the aircraft’s position.

Problems

Further information: Air traffic flow management

Sometimes, mistakes happen in air traffic control when planes get too close to each other. This can happen when controllers are very busy and might miss seeing some planes. These mistakes are more likely when there is a lot of activity in the sky.

Bad weather can cause big problems for flights. It makes planes delay, change their routes, or even cancel trips. In 2024, Europe saw many more delays because of weather than in 2023. Experts say we need better plans and faster solutions to help flights during bad weather.

Global air traffic control systems are different in every place. Some countries have new technology, but others still use older tools. This mix can cause delays and make it harder to keep flights safe. Experts say we need to update these systems to handle more planes and keep the skies safe.

Call signs

To keep airplanes safe while flying, each one gets a special name called a call sign. These names are given by a group of experts called ICAO and are used for planes that fly on regular schedules, as well as for some military planes .

Call signs can look like short letters followed by numbers, such as AAL872 or VLG1011. When talking on the radio, pilots and air traffic controllers use a different version of the call sign to make things clearer. For example, instead of saying "BAW832," they might say "Speedbird 832." If a plane doesn’t have a special call sign, controllers use the plane’s registration number, like 'N12345'. For quick radio calls, they might just say the last three letters or numbers, such as "alpha-bravo-charlie" for C-GABC or "three-four-five" for N12345. In the United States, they might also use the type of plane, like saying "Cessna 842" for N11842.

Technology

The Federal Aviation Administration has spent a lot of money on software, but a fully automatic system is still not ready. In 2002, the United Kingdom opened a new area control center at the London Area Control Centre in Swanwick, replacing an older center near London Heathrow Airport. The new center used software from Lockheed-Martin, but it had some problems at first with its software and communications.

There are several tools that help air traffic controllers. These include systems that process flight information, tools that check for possible conflicts in the next few minutes, and various decision support tools developed by NASA. There are also tools for managing traffic and keeping flights safe, as well as systems that record what controllers see and hear for later review.

Other systems, like those used by Nav Canada, help manage air traffic using modern technology, including satellites. These systems support air traffic control around the world.

Air navigation service providers (ANSPs) and air traffic service providers (ATSPs)

Main article: Air Navigation Service Provider

Air traffic control is managed by different groups in many countries. These groups help keep the sky safe by directing airplanes and making sure they don't crash into each other. Here are some of the groups that help with air traffic control around the world:

• Albania – Agjencia Nacionale e Trafikut Ajror
• Angola - Empresa Nacional de Navegação Aérea (ENNA)
• Armenia – Armenian Air Traffic Services (ARMATS)
• Australia – Airservices Australia (state agency) and Royal Australian Air Force.
• Austria – Austro Control
• Belgium – Skeyes (Successor of Belgocontrol)
• Brazil – Departamento de Controle de Tráfego Aéreo (military) and ANAC – Agência Nacional de Aviação Civil
• Bulgaria – Air Traffic Services Authority
• Canada – NAV CANADA
• Central America – Corporación Centroamericana de Servicios de Navegación Aerea
• Columbia – Aeronáutica Civil Colombiana
• Costa Rica – Dirección General de Aviacion Civil
• Croatia – Hrvatska kontrola zračne plovidbe (Croatia Control Ltd.)
• Cuba – IACC (Instituto de Aeronáutica Civil de Cuba)
• Czech Republic – Řízení letového provozu ČR
• Denmark – Naviair
• Dominican Republck – DGAC (Dirección General de Aeronáutica Civil)
• Estonia – Lennuliiklusteeninduse
• European Union – Eurocontrol – (European Organisation for the Safety of Air Navigation)
• Finland – Fintraffic Lennonvarmistus Oy
• France – Direction des Services de la Navigation Aérienne (DSNA), part of Direction générale de l’aviation civile: (state-owned)
• Georgia – SAKAERONAVIGATSIA, Ltd. (Georgian Air Navigation)
• Germany – DFS Deutsche Flugsicherung GmbH (state-owned); DFS Aviation Services GmbH (DAS – affiliate of DFS); Rhein-Neckar Flugplatz GmbH (Mannheim Airport); AustroControl (at some regional airports)
• Greece – Hellenic Civil Aviation Authority (HCAA)
• Guatemala – DGAC (Dirección General de Aeronáutica Civil)
• Hong Kong – CAD (state-owned)
• Hungary – HungaroControl Magyar Légiforgalmi Szolgálat Zrt. (HungaroControl Hungarian Air Navigation Services Pte. Ltd. Co.)
• India – Airports Authority of India (AAI) (department of ministry of civil aviation)
• Indonesia – Angkasa Pura II
• Ireland – AirNav Ireland
• Island – ISAVIA
• Italia – ENAV (state-owned)
• Jamaica – JCAA (Jamaica Civil Aviation Authority)
• Kenia - Kenya Civil Aviation Authority (KCAA)
• Latvia – (Latvian ATC)
• Lithuania – ANS (Lithuanian ATC)
• Luxembourg – Administration de la navigation aérienne (state-owned)
• Macedonia – DGCA (Macedonian ATC)
• Malaysia – DCA-Department of Civil Aviation
• Malta – Malta Air Traffic Services Ltd
• Mexico – Servicios a la Navegación en el Espacio Aéreo Mexicano
• Nepal – Civil Aviation Authority of Nepal
• Netherlands – Luchtverkeersleiding Nederland (LVNL)
• New Zealand – Airways New Zealand (state-owned)
• Norway – Avinor (Privatunternehmen im Staatsbesitz)
• Pakistan – Civil Aviation Authority of Pakistan (state-owned)
• Peru – Centro de Instrucción de Aviación Civil CIAC, Civil Aviation Training Center
• Philippines – Civil Aviation Authority of the Philippines (CAAP) (state-owned)
• Poland – PANSA – Polish Air Navigation Services Agency
• Portugal – NAV – (Portuguese ATC)
• Romania – Romanian Air Traffic Services Administration – (ROMATSA)
• Russia – Federal State Unitary Enterprise – (State ATM Corporation)
• Saudi-Arabia – General Authority of Civil Aviation (GACA)
• Serbia – Serbia and Montenegro Air Traffic Services Agency Ltd. (SMATSA)
• Singapore – CAAS (Civil Aviation Authority of Singapore)
• Slovakia – Letové prevádzkové služby Slovenskej republiky
• Slovenia – Slovenia Control
• South Africa – Air Traffic and Navigation Services
• Spain – ENAIRE
• Sweden – The LFV Group (Swedish ATC)
• Switzerland – Skyguide
• Taiwan – ANWS Civil Aeronautical Administration
• Tanzania - Tanzania Civil Aviation Authority (TCAA)
• Thailand – AEROTHAI (Aeronautical Radio of Thailand)
• Trinidad and Tobago – TTCAA (Trinidad and Tobago Civil Aviation Authority)
• Turkey – DGCA (Turkish Directorate General of Civil Aviation)
• Ukraine – Ukrainian State Air Traffic Service Enterprise (UkSATSE)
• United Arab Emirates – General Civil Aviation Authority (GCAA)
• United Kingdom – National Air Traffic Services (Public Private Partnership)
• United States – Federal Aviation Administration (state-owned)
• Venezuela – INAC (Instituto Nacional de Aviación Civil)
• Vietnam – Vietnam Air Traffic Management Corporation (VATM)
• Zambia – Zambia Civil Aviation Authority (ZCAA)
• Zimbabwe – Zimbabwe Civil Aviation Authority

Proposed changes

In the United States, some changes to air traffic control rules are being studied. One idea is called "free flight," where airplanes can choose their own paths using computers instead of following directions from a central controller.

Europe has a plan called the Single European Sky ATM Research to create new ways to manage air traffic for the future. There have been discussions about how to balance new technology with the needs of air traffic controllers. The EU wants to make air travel more efficient by using common digital standards and letting controllers work where they are most needed.

Many countries have changed how they manage air traffic control services. Some use government agencies, while others use private companies or non-profit groups. Each way has its own challenges and benefits. For example, Canada uses a private non-profit group called Nav Canada, which has helped make flights shorter, safer, and more efficient.

ATC regulations in the United States

In the United States, the sky is split into 21 sections called zones. Each zone has smaller parts called sectors. There are also special areas around airports called TRACON airspaces, about 50 miles wide. Inside these areas, each airport has its own small airspace, about 5 miles wide. Special workers called air traffic controllers follow specific rules in a book called FAA Order 7110.65 to keep planes safe and moving smoothly.