View source for Air traffic control

{{Short description|Service to direct pilots of aircraft}}
{{Redirect|Air traffic|the Canadian band|Air Traffic Control (band)|the Owl City song|Maybe I'm Dreaming}}
{{About|civilian direction of aircraft|other types of aircraft control|Air control (disambiguation){{!}}Air control}}
{{EngvarB|date=March 2025}}<!--this is a global service, first developed in the UK-->
{{Use dmy dates|date=March 2025}}
{{Multiple issues|
{{Original research|date=April 2019}}
{{More citations needed|date=April 2019}}
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[[File:New-MIAL-ATC-Tower.jpg|thumb|upright|The air traffic control tower of [[Mumbai International Airport]] in India]]

'''Air traffic control''' ('''ATC''') is a service provided by ground-based [[air traffic controller]]s 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, organise and expedite the flow of traffic in the air, and provide information and other support for pilots.<ref>{{Cite web |url=http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0201.html |title=FAA 7110.65 2-1-1 |website=FAA.gov |publisher=[[Federal Aviation Authority]] |date=n.d. |archive-url=https://web.archive.org/web/20100607105632/http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0201.html |archive-date=7 June 2010 }}</ref>

Personnel of air traffic control monitor aircraft location in their assigned airspace by [[radar]] and communicate with the [[pilot]]s by [[radio]].<ref>{{Cite web |title=How Air Traffic Control Works |url=https://www.caa.co.uk/Consumers/Guide-to-aviation/How-air-traffic-control-works/ |website=CAA.co.uk |publisher=[[Civil Aviation Authority (United Kingdom)|UK Civil Aviation Authority]] |date=n.d. |archive-date=26 February 2021 |archive-url=https://web.archive.org/web/20210226104734/https://www.caa.co.uk/Consumers/Guide-to-aviation/How-air-traffic-control-works/ }}</ref> To prevent collisions, ATC enforces [[Separation (air traffic control)|traffic separation]] rules, which ensure each aircraft maintains a minimum amount of 'empty space' around it at all times. It is also common for ATC to provide services to all [[General aviation|private]], [[Military aviation|military]], and commercial aircraft operating within its airspace; not just civilian aircraft.<ref>{{Cite web |title=Air Traffic Organization |url=https://www.faa.gov/about/office_org/headquarters_offices/ato |archive-url=http://web.archive.org/web/20250205013527/https://www.faa.gov/about/office_org/headquarters_offices/ato |archive-date=5 February 2025 |access-date=15 February 2025 |website=FAA.gov |publisher=Federal Aviation Administration }}</ref> Depending on the type of flight and the class of airspace, ATC may issue ''instructions'' that pilots are required to obey, or ''advisories'' (known as ''flight information'' in some countries) that pilots may, at their discretion, disregard. The [[pilot in command]] of an aircraft always retains final authority for its safe operation, and may, in an emergency, deviate from ATC instructions to the extent required to maintain safe operation of the aircraft.<ref>{{Cite web |title=Electronic Code of Federal Regulations (eCFR) |url=https://www.ecfr.gov |website=ECFR.gov |publisher=Electronic Code of Federal Regulations (eCFR) |date=n.d. |access-date=21 January 2021 }}</ref>

==Language==
Pursuant to requirements of the [[International Civil Aviation Organization]] (ICAO), ATC operations are conducted either in the English language, or the local language used by the station on the ground.<ref name="IDAO-FAQ">{{Cite web |url=http://www.icao.int/icao/en/trivia/peltrgFAQ.htm#23 |title=IDAO FAQ |website=ICAO.int |publisher=[[International Civil Aviation Organization]] |date=n.d. |access-date=3 March 2009 |url-status=live |archive-url=https://web.archive.org/web/20090220142943/http://icao.int/icao/en/trivia/peltrgFAQ.htm |archive-date=20 February 2009 }}</ref> In practice, the native language for a region is used; however, English must be used upon request.<ref name="IDAO-FAQ" />

{{See also|Aeronautical phraseology|Aviation English}}

==History==
In 1920, [[Croydon Airport]] near London, England, was the first [[airport]] in the world to introduce air traffic control.<ref>{{Cite web |url=http://www.transportheritage.com/find-heritage-locations.html?sobi2Task=sobi2Details&catid=91&sobi2Id=273 |title=Heritage locations – South East – Surrey – Croydon Airport |archive-url=https://web.archive.org/web/20180925180501/http://www.transportheritage.com/find-heritage-locations.html?sobi2Task=sobi2Details&catid=91&sobi2Id=273 |archive-date=25 September 2018 }}</ref>  The 'aerodrome control tower' was a wooden hut {{Convert|15|ft|0|abbr=off}} high with windows on all four sides.  It was commissioned on 25 February 1920, and provided basic traffic, weather, and location information to pilots.<ref>{{Cite news |last=Kaminski-Morrow |first=David |date=25 February 2020 |title=Colourised Images Mark Centenary of World's First Control Tower |url=https://www.flightglobal.com/safety/colourised-images-mark-centenary-of-worlds-first-control-tower/136903.article |work=Flight Global }}</ref><ref>{{Cite news |url=https://www.bbc.co.uk/news/av/uk-england-london-51648067/croydon-airport-100-years-of-air-traffic-control-in-the-uk |title=How a Hut in Croydon Changed Air Travel |work=BBC News |access-date=2 March 2020 }}</ref>

In the United States, air traffic control developed three divisions. The first of several air mail radio stations (AMRS) was created in 1922, after World War I, when the U.S. Post Office began using techniques developed by the [[U.S. Army]] to direct and track the movements of [[reconnaissance aircraft]]. Over time, the AMRS morphed into [[flight service station]]s. Today's flight service stations do not issue control instructions, but provide pilots with many other flight related informational services. They do relay control instructions from ATC in areas where flight service is the only facility with radio or phone coverage. The first airport traffic control tower, regulating arrivals, departures, and surface movement of aircraft in the US at a specific airport, opened in Cleveland in 1930. Approach- and departure-control facilities were created after adoption of radar in the 1950s to monitor and control the busy airspace around larger airports. The first air route traffic control center (ARTCC), which directs the movement of aircraft between departure and destination, was opened in Newark in 1935, followed in 1936 by Chicago and Cleveland.<ref>FAA Historical Chronology, 1926–1996</ref> 

After the [[1956 Grand Canyon mid-air collision]], killing all 128 on board, the FAA was given the air-traffic responsibility in the United States in 1958, and this was followed by other countries.<!--ref name=Economist15jun2019--> In 1960, Britain, France, Germany, and the [[Benelux]] countries set up [[Eurocontrol]], intending to merge their airspaces.<!--ref name=Economist15jun2019--> The first and only attempt to pool controllers between countries is the [[Maastricht Upper Area Control Centre]] (MUAC), founded in 1972 by Eurocontrol, and covering Belgium, Luxembourg, the Netherlands, and north-western Germany.<!--ref name=Economist15jun2019--> In 2001, the [[European Union]] (EU) aimed to create a '[[Single European Sky]]', hoping to boost efficiency and gain economies of scale.<ref name="Economist15jun2019">{{Cite news |url=https://www.economist.com/international/2019/06/15/air-traffic-control-is-a-mess |title=Air-traffic control is a mess |newspaper=[[The Economist]] |date=15 June 2019 }}</ref>

In the USSR, the first air traffic control service was organized in 1929 on the [[Moscow]] - [[Irkutsk]] air route; in 1930, control areas were defined along all existing air routes.<ref>Н. Зыков. Дирижеры воздушных трасс // журнал «[[Nauka i Zhizn|Наука и жизнь]]», № 12, 1981. стр.58-59</ref>

==Airport traffic control tower<span class="anchor" id="ATCT"></span>==
[[File:AeroportoGuarulhos Torre2.jpg|thumb|upright|Control tower at [[São Paulo–Guarulhos International Airport]]]]
[[File:Control tower at Birmingham Airport, England 27June2019 arp.jpg|thumb|upright|Control tower at [[Birmingham Airport]], England]]
[[File:Lennonjohtotorni.JPG|thumb|upright|Small control tower at [[Räyskälä Airfield]] in [[Loppi]], Finland]]

The primary method of controlling the immediate airport environment is visual observation from the airport control tower.  The tower is typically a tall, windowed structure, located within the airport grounds.  The [[air traffic controller]]s, usually abbreviated 'controller', are responsible for separation and efficient movement of aircraft and vehicles operating on the taxiways and runways of the airport itself, and aircraft in the air near the airport, generally {{Convert|5|to|10|nmi|0|abbr=off|lk=on}}, depending on the airport procedures.  A controller must carry out the job using the precise and effective application of rules and procedures; however, they need flexible adjustments according to differing circumstances, often under time pressure.<ref>{{cite document |last=Costa|first=G|date=1995|title=Occupational stress and stress prevention in air traffic|publisher=International Labour Office, Working paper: CONDI/T/WP.6/1995|location=Geneva}}</ref>  In a study that compared stress in the general population and this kind of system markedly showed more stress level for controllers.  This variation can be explained, at least in part, by the characteristics of the job.<ref>{{cite journal |last1=Arghami|first1=S. |last2=Seraji|first2=J.N. |last3=Mohammad|first3=K. |last4=Zamani|first4=G.H. |last5=Farhangi|first5=A. |last6=Van Vuuren|first6=W. |date=2005|title=Mental health in high-tech system|journal=Iranian Journal of Public Health. 2005:31-7.}}</ref>

[[Remote and virtual tower]] (RVT) is a system based on air traffic controllers being located somewhere other than at the local airport tower, and still able to provide air traffic control services.<ref>{{Cite web |url=https://canso.fra1.digitaloceanspaces.com/uploads/2020/12/CANSO-SDT-Remote-Tower-Guidance.pdf |title=CANSO Guidance Material for Remote and Digital Towers |page=5 |publisher=[[Civil Air Navigation Services Organisation]] (CANSO) |date=January 2021 |access-date=23 August 2023 }}</ref><ref>{{Cite web |title=Guidance Material on Remote Aerodrome Air Traffic Services |url=https://www.easa.europa.eu/en/downloads/71515/en |publisher=[[European Union Aviation Safety Agency]] (EASA) |date=15 February 2019 |access-date=23 August 2023 }}</ref><ref>{{Cite web |title=Thirteenth Air Navigation Conference, Montréal, Canada, 9 to 19 October 2018, Committee A, Agenda item 3: Enhancing the global air navigation system, 3.5: Other ATM issues: Digitisation of Aerodrome Air Traffic Services |url=https://www.icao.int/Meetings/anconf13/Documents/WP/wp_174_en.pdf |publisher=[[International Civil Aviation Organization]] (ICAO) |date=9–19 October 2018 |access-date=23 August 2023 }}</ref>

===Ground control===
[[File:Pope Field Air Traffic Control Tower (9206250542).jpg|thumb|left|Inside [[Pope Field]] air traffic control tower]]

Ground control (sometimes known as {{Em|ground movement control}}, GMC) is responsible for the airport {{Em|movement}} areas.<ref name="Smith 2021" />

Some busier airports have surface movement radar (SMR).<ref name="Smith 2021" />

===Air control or local control===
Air control (known to pilots as {{Em|tower}} or {{Em|tower control}}) is responsible for the active runway surfaces.<ref name="Smith 2021" />

===Flight data and clearance delivery===
Clearance delivery is the position that issues route clearances to aircraft, typically before they commence taxiing.  These clearances contain details of the route that the aircraft is expected to fly after departure.<ref name="Smith 2021" />

==Approach and terminal control==
{{Redirect|TRACON|the video game series|TRACON (series)}}
[[File:Potomac Consolidated TRACON.jpg|thumb|[[Potomac Consolidated TRACON]] in [[Warrenton, Virginia]], United States]]

In the U.S., TRACONs are additionally designated by a three-digit alphanumeric code.  For example, the Chicago TRACON is designated C90.<ref>{{Cite web|title=Terminal Radar Approach Control Facilities (TRACON)|url=http://www.faa.gov/about/office_org/headquarters_offices/ato/tracon/|website=FAA.gov|publisher=[[Federal Aviation Administration]]|access-date=22 February 2014}}</ref>

{{See also|Terminal control area}}

==Area control centre / en-route centre==
{{Main|Area control center}}
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[[File:AirTraffic-8.jpg|thumb|The training department at the Washington Air Route Traffic Control Center, [[Leesburg, Virginia]], United States]]

===General characteristics===
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===Radar coverage===
<!--"Radar" links here.-->
[[File:Grandballonsud.jpg|thumb|Unmanned radar on a remote mountain]]

Some air navigation service providers (e.g., Airservices Australia, the U.S. Federal Aviation Administration, [[Nav Canada]], etc.) have implemented [[automatic dependent surveillance – broadcast]] (ADS-B) as part of their surveillance capability.  This newer technology reverses the radar concept.  Instead of radar 'finding' a target by interrogating the transponder, the ADS-B equipped aircraft 'broadcasts' a position report as determined by the [[navigation]] equipment on board the aircraft.  ADS-C is another mode of automatic dependent surveillance, however ADS-C operates in the 'contract' mode, where the aircraft reports a position, automatically or initiated by the pilot, based on a predetermined time interval.  It is also possible for controllers to request more frequent reports to more quickly establish aircraft position for specific reasons.  However, since the cost for each report is charged by the ADS service providers to the company operating the aircraft,{{Disputed inline|ADS-B|date=March 2014}} more frequent reports are not commonly requested, except in emergency situations.  ADS-C is significant, because it can be used where it is not possible to locate the infrastructure for a radar system (e.g., over water).  Computerised radar displays are now being designed to accept ADS-C inputs as part of their display.<ref>{{Cite web |title=Automatic Dependent Surveillance - Contract (ADS-C) |url=https://www.skybrary.aero/index.php/Automatic_Dependent_Surveillance_-_Contract_(ADS-C) |website=SKYbrary.aero |publisher=SKYbrary Aviation Safety |access-date=23 February 2021 }}</ref>{{Verification needed|date=March 2025}}

A radar archive system (RAS) keeps an electronic record of all radar information, preserving it for a few weeks.  This information can be useful for [[search and rescue]].  When an aircraft has 'disappeared' from radar screens, a controller can review the last radar returns from the aircraft to determine its likely position.  For an example, see the crash report in the following citation.<ref>{{Cite web |title=crash report |url=http://www.tsb.gc.ca/eng/rapports-reports/aviation/1996/a96a0207/a96a0207.asp |website=TSB.gc.ca |publisher= |date=1996 |access-date=24 August 2010 |archive-url=https://web.archive.org/web/20120307102104/http://www.tsb.gc.ca/eng/rapports-reports/aviation/1996/a96a0207/a96a0207.asp |archive-date=7 March 2012 |url-status=dead}}</ref>

===Flight traffic mapping===
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==Problems==

===Traffic===
{{Further|Air traffic flow management}}
[[File:Air traffic heathrow.JPG|thumb|Intersecting [[contrail]]s of aircraft over London, an area of high air traffic]]

Air traffic control errors occur when the separation (either vertical or horizontal) between airborne aircraft falls below the minimum prescribed separation set (for the domestic United States) by the US Federal Aviation Administration.  Separation minimums for terminal control areas (TCAs) around airports are lower than en-route standards.  Errors generally occur during periods following times of intense activity, when controllers tend to relax and overlook the presence of traffic and conditions that lead to loss of minimum separation.<ref>{{cite document |last1=Breitler|first1=Alan|last2=Kirk|first2=Kevin|date=September 1996|title=Effects of Sector Complexity and Controller Experience on Probability of Operational Errors in Air Route Traffic Control Centers|publisher=Center for Naval Analyses Document (IPR 95-0092)}}</ref>{{Text-source inline|date=April 2022}}

===Weather===
[[File:PSX 20150807 202515.jpg|thumb|Aircraft taking off from [[Dallas/Fort Worth International Airport]] with the ATC tower in the background.]]According to the Civil Air Navigation Services Organisation (CANSO), weather significantly impacts global aviation, with more than 70% of air traffic delays being attributed to adverse weather conditions. These disruptions cause widespread delays, rerouting by ATC, and cancellations across continents. In 2024, Europe experienced a 40% increase in weather-related en-route delays compared to 2023. As climate change intensifies the frequency and severity of these events, CANSO urges collaboration and real-time solutions among global aviation stakeholders to mitigate the increased effects of weather on flight operations.<ref>{{Cite web |title=The weather impact on global Air Traffic Management operations and how to solve it |url= https://canso.org/the-weather-impact-on-global-air-traffic-management-operations-and-how-to-solve-it |publisher=Civil Air Navigation Services Organisation (CANSO) |date=7 August 2024 |access-date=9 May 2025 }}</ref>

===Infrastructure=== 
Global ATC infrastructure is a complex network that varies significantly by region, with many countries facing challenges related to outdated technology, staffing shortages, and increasing traffic demand. While some regions, like parts of Europe and the U.S., have implemented modernization programs such as SESAR and NextGen,<ref>{{Cite web |title=Next Generation Air Transportation System |url=https://www.faa.gov/nextgen |publisher=Federal Aviation Administration (FAA) |date=14 January 2025 |access-date=9 May 2025 }}</ref> many others, especially in developing nations, still rely on legacy radar systems and voice-based communication, which limit efficiency and safety. These disparities contribute to delays and reduce the overall resilience of global air traffic management. According to the ICAO, coordinating ATC systems and accelerating digitalization is essential for meeting future aviation demands.<ref>{{Cite web |title=Global Air Navigation Plan 2023 Edition |url=https://www.icao.int/airnavigation/pages/ganp-resources.aspx |publisher=International Civil Aviation Organization (ICAO) |date=2023 |access-date=9 May 2025 }}</ref>  Similarly, a 2024 report from the International Air Transport Association (IATA) emphasizes the urgency of investing in scalable, data-driven infrastructure to handle post-pandemic growth and ensure sustainability across the network.<ref>{{Cite web |title=Air Traffic Management Infrastructure Report |url= https://www.iata.org/contentassets/c81222d96c9a4e0bb4ff6ced0126f0bb/iata-annual-review-2024.pdf |publisher=International Air Transport Association (IATA) |date=15 February 2024 |access-date=9 May 2025 }}</ref>

===Congestion===
Constrained control capacity and growing traffic lead to [[flight cancellation and delay]]s.<ref>{{Cite news |last=Harkoftaki |first=Matina |date=2 April 2025 |title=Air traffic congestion over Athens causes delays |url=https://www.ekathimerini.com/economy/1265935/air-traffic-congestion-over-athens-causes-delays/ |publisher=ekathimerini |access-date=13 May 2025 }}</ref><ref>{{Cite news |last=Davies |first=Phil |date=3 March 2025 |title=Air traffic control delays and congestion hit Norse Atlantic performance |url=https://travelweekly.co.uk/news/air-traffic-control-delays-and-congestion-hit-norse-atlantic-performance |publisher=Travel Weekly |access-date=13 May 2025 }}</ref>

* In America, delays caused by ATC grew by 69% between 2012 and 2017.<ref name="Economist15jun2019" />  ATC staffing issues were a major factor in congestion.<ref>{{Cite web|last=Gilbert|first=Trish|date=15 June 2016|title=Air traffic control staffing shortage must be addressed|url=https://thehill.com/blogs/congress-blog/technology/283328-air-traffic-control-staffing-shortage-must-be-addressed/|website=The Hill|access-date=12 August 2022}}</ref><!--ref name=Economist15jun2019-->
By then the market for air-traffic services was worth $14bn.<!--ref name=Economist15jun2019-->  More efficient ATC could save 5-10% of aviation fuel by avoiding [[holding pattern]]s and indirect [[Airway (aviation)|airway]]s.<ref name="Economist15jun2019" />

The military takes 80% of Chinese airspace, congesting the thin corridors open to airliners.<!--ref name=Economist15jun2019-->  The United Kingdom closes its military airspace only during [[British Armed Forces|military]] exercises.<ref name=Economist15jun2019/>

==Call signs==
A prerequisite to safe air traffic separation is the assignment and use of distinctive [[call sign]]s.  These are permanently allocated by [[ICAO]] on request, usually to [[Scheduled air transport|scheduled flights]], and some air forces and other military services for [[Military aviation|military flights]].  There are written call signs with a two or three&nbsp;letter combination followed by the flight number such as AAL872 or VLG1011.  As such, they appear on flight plans and ATC radar labels.  There are also the ''audio'' or ''radio-telephony'' call signs used on the radio contact between pilots and air traffic control.  These are not always identical to their written counterparts.  An example of an audio call sign would be 'Speedbird 832', instead of the written 'BAW832'.  This is used to reduce the chance of confusion between ATC and the aircraft.  By default, the call sign for any other flight is the [[Aircraft registration|registration number]] (or tail number in US parlance) of the aircraft, such as 'N12345', 'C-GABC', or 'EC-IZD'.  The short ''radio-telephony'' call signs for these tail numbers is the last three letters using the [[NATO phonetic alphabet]] (e.g. ABC, spoken ''alpha-bravo-charlie'' for C-GABC), or the last three numbers (e.g. ''three-four-five'' for N12345).  In the United States, the prefix may be an aircraft type, model, or manufacturer in place of the first registration character, for example, 'N11842' could become 'Cessna 842'.<ref>{{Cite web|url=http://atccommunication.com/what-is-an-abbreviated-aircraft-call-sign|title=What is an abbreviated aircraft call sign?|work=ATC Communication|access-date=3 July 2015|archive-date=20 October 2018|archive-url=https://web.archive.org/web/20181020165819/http://atccommunication.com/what-is-an-abbreviated-aircraft-call-sign|url-status=dead}}</ref>

==Technology==
The [[Federal Aviation Administration]] (FAA) has spent over US$3&nbsp;billion on software, but a fully automated system is still yet to be achieved.  In 2002, the United Kingdom commissioned a new area control centre into service at the [[London Area Control Centre]] (LACC) at [[Swanwick, Hampshire|Swanwick]] in Hampshire, relieving a busy suburban centre at [[West Drayton]] in Middlesex, north of [[London Heathrow Airport]].  Software from [[Lockheed-Martin]] predominates at the London Area Control Centre.  However, the centre was initially troubled by software and communications problems causing delays and occasional shutdowns.<ref>{{Cite web|title=Air Traffic Control|url=https://sites.google.com/site/zagorakis1977/theory/air-traffic-control/technology|website=sites.Google.com|publisher= |date= |access-date=4 December 2012}}</ref>

Some tools are available in different domains to help the controller further:
* Flight data processing systems: this is the system (usually one per centre) that processes all the information related to the flight (the flight plan), typically in the time horizon from gate to gate (airport departure / arrival gates).  It uses such processed information to invoke other flight plan related tools (such as e.g. [[Medium Term Conflict Detection]] (MTCD).<ref name="skybrary-MTCD">{{cite web |title=Medium Term Conflict Detection (MTCD) |url=https://skybrary.aero/articles/medium-term-conflict-detection-mtcd |website=skybrary.aero |publisher=SKYbrary Aviation Safety |access-date=3 November 2024}}</ref>
* [[Short-term conflict alert]] (STCA) that checks possible conflicting trajectories in a time horizon of about two or three minutes (or even less in approach context; 35 seconds in the French Roissy & Orly approach centres).<ref>{{Cite web|title=Le filet de sauvegarde resserre ses mailles|url=http://www.dgac.fr/html/publicat/av_civil/them_1/them_1_34_35.pdf|website=dgac.fr|archive-url=https://web.archive.org/web/20090327181434/http://www.dgac.fr/html/publicat/av_civil/them_1/them_1_34_35.pdf|archive-date=27 March 2009|language=fr}}</ref>
* Center TRACON automation system (CTAS): a suite of human centred decision support tools developed by NASA Ames Research Center.  Several of the CTAS tools have been field tested and transitioned to the FAA for operational evaluation and use.  Some of the CTAS tools are: traffic management advisor (TMA), passive final approach spacing tool (pFAST), collaborative arrival planning (CAP), direct-to (D2), en route descent advisor (EDA), and multi-center TMA.  The software is running on Linux.<ref>{{Cite web|url=http://www.usenix.org/events/usenix02/tech/techthurs.html|title=Technical Sessions|publisher=usenix.org|access-date=5 December 2010}}</ref>
* MTCD and URET:
** In Europe, several [[MTCD]] tools are available: {{Not a typo|iFACTS}} ([[National Air Traffic Services]]), VAFORIT ([[Deutsche Flugsicherung]]), new FDPS ([[Eurocontrol#Maastricht Upper Area Control Centre|Maastricht Upper Area Control]]).  The [[Single European Sky ATM Research]] (SESAR).<ref name="SESARref">{{Cite web|url=http://www.eurocontrol.int/sesar/public/subsite_homepage/homepage.html|title=SESAR|website=Eurocontrol.int|publisher=[[Eurocontrol]]|date= |archive-url=https://web.archive.org/web/20080925061303/http://www.eurocontrol.int/sesar/public/subsite_homepage/homepage.html|archive-date=25 September 2008}}</ref>
[[File:TATIC Electronic Flight Strip system at Sao Paulo Itnl.jpg|thumb|Electronic flight progress strip system at São Paulo Intl. control tower – ground control]]
* The Nav Canada system known as EXCDS.<ref>{{Cite web|url=http://www.navcanada.ca/NavCanada.asp?Language=en&Content=ContentDefinitionFiles\TechnologySolutions\products\IIDS\excds\default.xml|title=Technology Solutions – Integrated Information Display System (IIDS) – Extended Computer Display System (EXCDS)|website=Nav Canada|url-status=dead|archive-url=https://web.archive.org/web/20040616113203/http://www.navcanada.ca/NavCanada.asp?Language=en&Content=ContentDefinitionFiles%5CTechnologySolutions%5Cproducts%5CIIDS%5Cexcds%5Cdefault.xml|archive-date=16 June 2004}}</ref>
* Screen content recording: hardware or software based recording function which is part of most modern automation system, and that captures the screen content shown to the ATCO.  Such recordings are used for a later replay together with audio recording for investigations and post event analysis.<ref>{{Cite web|url=http://www.epiphan.com/solutions_new/?arid=995|title=Solutions using Epiphan products|work=Epiphan Video capture, stream, record|access-date=3 July 2015|archive-date=15 February 2014|archive-url=https://web.archive.org/web/20140215055917/http://www.epiphan.com/solutions_new/?arid=995|url-status=dead}}</ref>
* Communication navigation surveillance / air traffic management ([[Communication, navigation and surveillance|CNS / ATM]]) systems are communications, navigation, and surveillance systems, employing digital technologies, including satellite systems, together with various levels of automation, applied in support of a seamless global air traffic management system.<ref>{{Cite web |title=CNS/ATM Systems |url=http://www.icao.int/icao/en/ro/rio/execsum.pdf |website=icao.int |archive-url=https://web.archive.org/web/20111109123519/http://www.icao.int/icao/en/ro/rio/execsum.pdf |archive-date=9 November 2011 |pages=10 }}</ref>

==Air navigation service providers (ANSPs) and air traffic service providers (ATSPs)==
{{Main|Air Navigation Service Provider}}
{{Incomplete list|date=March 2025}}
* Spain – [[AENA]] now [[AENA S.A.]] (Spanish Airports) and [[ENAIRE]] (ATC & ATSP)<ref>{{Cite web|url=http://www.enaire.es/csee/Satellite/Enaire/es/Enaire.html|title=Acerca de ENAIRE – ENAIRE – Información corporativa|access-date=3 July 2015|url-status=dead|archive-url=https://web.archive.org/web/20150704122232/http://www.enaire.es/csee/Satellite/Enaire/es/Enaire.html|archive-date=4 July 2015}}</ref>
* Vietnam – Vietnam Air Traffic Management Corporation (VATM)<ref>{{Cite web|title=Company profile – Viet Nam Air Traffic Management Corporation|url=https://vatm.vn/en/company-profile-s741.html|archive-url=https://web.archive.org/web/20170930022053/http://vatm.vn/en/company-profile-s741.html|url-status=dead|archive-date=30 September 2017|website=VATM.vn|access-date=23 January 2024}}</ref>
* Zambia – Zambia Civil Aviation Authority (ZCAA)<ref>{{Cite web|url=http://www.caa.co.zm/|title=Zambia Civil Aviation Authority - home|website=CAA.co.zm|access-date=2 August 2019|archive-date=2 August 2019|archive-url=https://web.archive.org/web/20190802015854/http://www.caa.co.zm/|url-status=dead}}</ref>
* Zimbabwe – Zimbabwe Civil Aviation Authority<ref>{{Cite web|title=Civil Aviation Authority of Zimbabwe|url=https://www.caaz.co.zw/|website=www.caaz.co.zw|access-date=9 May 2021|archive-date=29 June 2019|archive-url=https://web.archive.org/web/20190629142236/https://www.caaz.co.zw/|url-status=dead}}</ref>

==Proposed changes==
In the United States, some alterations to traffic control procedures are being examined:
* [[Free flight (air traffic control)|Free flight]] is a developing air traffic control method that uses no centralised 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.<ref>{{Cite magazine|last=Leslie|first=Jacques|date=|url=https://www.wired.com/wired/archive/4.04/es.faa.html|title=Wired 4.04: Free Flight|magazine=Wired|access-date=3 July 2015}}</ref>

<!--EU-->
In Europe, the [[Single European Sky ATM Research]] (SESAR)<ref name=SESARref/> programme plans to develop new methods, technologies, procedures, and systems to accommodate future (2020 and beyond) air traffic needs.  In October 2018, European controller unions dismissed setting targets to improve ATC as "a waste of time and effort", as new technology could cut costs for users but threaten their jobs.<!--ref name=Economist15jun2019-->  In April 2019, the EU called for a 'Digital European Sky', focusing on cutting costs by including a common digitisation standard, and allowing controllers to move to where they are needed instead of merging national ATCs, as it would not solve all problems.<!--ref name=Economist15jun2019-->  Single air-traffic control services in continent-sized America and China does not alleviate congestion.<!--ref name=Economist15jun2019-->  Eurocontrol tries to reduce delays by diverting flights to less busy routes: flight paths across Europe were redesigned to accommodate the new airport in Istanbul, which opened in April, but the extra capacity will be absorbed by rising demand for air travel.<ref name=Economist15jun2019/>

<!--salary-->
Well-paid jobs in western Europe could move east with cheaper labour.<!--ref name=Economist15jun2019-->  The average Spanish controller earn over €200,000 a year, over seven times the country average salary, more than pilots, and at least ten controllers were paid over €810,000 ($1.1m) a year in 2010.<!--ref name=Economist15jun2019-->  French controllers spent a cumulative nine months on strike between 2004 and 2016.<ref name=Economist15jun2019/>

===Privatisation===
Many countries have also privatised or corporatised their air navigation service providers.<ref>{{Cite journal |last1=McDougall|first1=Glen|last2=Roberts|first2=Alasdair S|date=15 August 2007|title=Commercialising Air Traffic Control: Have the reforms worked?|journal=Canadian Public Administration|page=Vol. 51, No. 1, pp. 45–69, 2009|ssrn=1317450}}</ref>  There are several models that can be used for ATC service providers.  The first is to have the ATC services be part of a government agency as is currently the case in the United States.  The problem with this model is that funding can be inconsistent, and can disrupt the development and operation of services.  Sometimes funding can disappear when lawmakers cannot approve budgets in time.  Both proponents and opponents of privatisation recognise that stable funding is one of the major factors for successful upgrades of ATC infrastructure.  Some of the funding issues include sequestration and politicisation of projects.<ref>{{Cite web|author=American Federation of Government Employees|display-authors=et al|url=https://www.passmember.org/images/congressional_letters/FAA%20Labor%20Unions%20Oppose%20ATC%20Privatization.pdf|archive-url=https://web.archive.org/web/20221231102311/https://www.passmember.org/images/congressional_letters/FAA%20Labor%20Unions%20Oppose%20ATC%20Privatization.pdf|url-status=dead|archive-date=31 December 2022|title=FAA Labor Unions Oppose ATC Privatization|website=Professional Aviation Safety Specialists|access-date=25 November 2016}}</ref>  Proponents argue that moving ATC services to a private corporation could stabilise funding over the long term which will result in more predictable planning and rollout of new technology as well as training of personnel. As of November 2024, The United States had 265 contractor towers that are staffed by private companies but administered by FAA through its FAA Contract Tower Program, which was established in 1982. These contract control towers cover 51% of all the Federal air traffic control towers in the U.S.<ref>{{cite web |title=FAA Contract Tower Program |url=https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/mission_support/faa_contract_tower_program |publisher=[[Federal Aviation Administration]] |access-date=4 January 2025 |date=25 November 2024 }}</ref>

Another model is to have ATC services provided by a government corporation.  This model is used in Germany, where funding is obtained through user fees.  Yet another model is to have a for-profit corporation operate ATC services.  This is the model used in the United Kingdom, but there have been several issues with the system there, including a large-scale failure in December 2014 which caused delays and cancellations and has been attributed to cost-cutting measures put in place by this corporation.  In fact, earlier that year, the corporation owned by the German government won the bid to provide ATC services for Gatwick Airport in the United Kingdom.  The last model, which is often the suggested model for the United States to transition to is to have a non-profit organisation that would handle ATC services as is used in Canada.<ref>{{Cite journal |last=Rinaldi |first=Paul |date=2015 |title=Safety and Efficiency Must Remain the Main Mission |journal=The Journal of Air Traffic Control |volume=57 |issue=2 |pages=21–23 }}</ref>

The Canadian system is the one most often used as a model by proponents of privatisation.  Air traffic control privatisation has been successful in Canada with the creation of Nav Canada, a private non-profit organisation which has reduced costs, and has allowed new technologies to be deployed faster due to the elimination of much of the bureaucratic [[red tape]].  This has resulted in shorter flights and less fuel usage.  It has also resulted in flights being safer due to new technology.  Nav Canada is funded from fees that are collected from the airlines based on the weight of the aircraft and the distance flown.<ref>{{Cite journal |last=Crichton |first=John |date=2015 |title=The NAV CANADA Model |journal=The Journal of Air Traffic Control |volume=57 |issue=2 |pages=33–35 }}</ref>

<!--privatisation-->
Air traffic control is operated by national governments with few exceptions: in the [[European Union]], only Italy has private shareholders.<ref name="Economist15jun2019" />  Privatisation does not guarantee lower prices: the profit margin of MUAC was 70% in 2017, as there is no competition, but governments could offer fixed terms [[Concession (contract)|concession]]s.<ref name="Economist15jun2019" /> 

==ATC regulations in the United States==
The United States airspace is divided into 21 zones (centres), and each zone is divided into sectors. Also within each zone are portions of airspace, about {{Convert|50|mi|km|abbr=off}} in diameter, called TRACON (Terminal Radar Approach Control) airspaces. Within each TRACON airspace are a number of airports, each of which has its own airspace with a {{Convert|5|mi|km|abbr=off}} radius. [[FAA]] [[control tower operator]]s (CTO) / [[air traffic controller]]s use [[FAA Order 7110.65]] as the authority for all procedures regarding air traffic.<ref>{{Cite web |url=http://www.faa.gov/documentlibrary/media/order/atc.pdf |title=Air Traffic Plans and Publications |website=FAA.gov |access-date=5 December 2010 |url-status=live |archive-url=https://web.archive.org/web/20090510140116/http://www.faa.gov/documentLibrary/media/Order/ATC.pdf |archive-date=10 May 2009 }}</ref>

==See also==
{{Portal|Aviation}}
{{Div col|colwidth=24em}}
* {{Annotated link|Air traffic service}}
* {{Annotated link|Flight information service officer}}
* {{Annotated link|Flight planning}}
* [[International Civil Aviation Organization#Use of the International System of Units|ICAO recommendations on use of the International System of Units]]
* {{Annotated link|Forward air control}}
* {{Annotated link|Global air-traffic management}}
* [[List of tallest air traffic control towers in the United States]]
* {{Annotated link|RMCDE}}
* [[Tower en route control]] (TEC)
{{Div col end}}

==References==
{{Reflist|refs=

<ref name="Smith 2021">{{Cite book |last=Smith |first=David |date=2021 |title=Air Traffic Control Handbook |publisher=Crécy Publishing |location=[[Manchester]] |isbn=978-1-9108-0999-0 }}</ref>

}}

==External links==
{{Commons category}}
* {{Internet Archive short film|id=gov.archives.arc.43449|name=A Traveler Meets Air Traffic Control (1963)}}
* [https://www.youtube.com/watch?v=8pYiC7bTUxQ NASA video of US air traffic]
* [https://www.youtube.com/watch?v=lQnAadKn1Es&index=30 Radar antennas in air traffic management] ([[YouTube]]-video, part of a video series about radar basics)

{{Air traffic control}}
{{Commercial air travel}}
{{Authority control}}

[[Category:Air traffic control| ]]
[[Category:Radar]]