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101-602: The authority regulates the safety standards of Irish civil aviation. The authority was originally established on 1 January 1994 under the Irish Aviation Authority Act, 1993 . The new IAA was established on 30 April 2023. Until 30 April 2023, the IAA was also responsible for providing air traffic control services to Ireland's three main airports, namely Dublin , Shannon and Cork , and en-route air traffic control services over Irish airspace. On that date,

202-477: A ' Flight Information Service ', which is similar to flight following. In the United Kingdom, it is known as a 'basic service'. En-route air traffic controllers issue clearances and instructions for airborne aircraft, and pilots are required to comply with these instructions. En-route controllers also provide air traffic control services to many smaller airports around the country, including clearance off

303-631: A Greenfield site, this ATCC became fully operational in February 2004 and replaces the ATC Centre at Shannon Airport which had been in operation since 1966. The new ATC centre houses the Shannon element of the new Air Traffic Management (ATM) system introduced in Shannon and Dublin in 2004. The authority was also responsible for providing communications in Shanwick airspace, with NATS providing

404-464: A block of airspace around multiple military aircraft. They are treated as one, and given only one data tag on the controller's scope. If any two aircraft are separated by less than the vertical separation minimum, then some form of horizontal separation must exist. Procedural separation, or more technically, temporal separation , is separation based upon the position of the aircraft, based strictly on timing . It therefore does not necessarily require

505-400: A bordering terminal or approach control). Terminal control is responsible for ensuring that aircraft are at an appropriate altitude when they are handed off, and that aircraft arrive at a suitable rate for landing. Not all airports have a radar approach or terminal control available. In this case, the en-route centre or a neighbouring terminal or approach control may co-ordinate directly with

606-433: A certain airport or airspace becomes a factor, there may be ground 'stops' (or 'slot delays'), or re-routes may be necessary to ensure the system does not get overloaded. The primary responsibility of clearance delivery is to ensure that the aircraft has the correct aerodrome information, such as weather and airport conditions, the correct route after departure, and time restrictions relating to that flight. This information

707-416: 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. RAS is also useful to technicians who are maintaining radar systems. The mapping of flights in real-time is based on the air traffic control system, and volunteer ADS-B receivers. In 1991, data on the location of aircraft was made available by

808-482: A cumulative nine months on strike between 2004 and 2016. Separation (air traffic control) 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

909-400: A distance of 100 nautical miles (185 kilometres; 115 miles). Terminal controllers are responsible for providing all ATC services within their airspace. Traffic flow is broadly divided into departures, arrivals, and overflights. As aircraft move in and out of the terminal airspace, they are 'handed off' to the next appropriate control facility (a control tower, an en-route control facility, or

1010-432: A large airspace area, they will typically use long-range radar, that has the capability, at higher altitudes, to see aircraft within 200 nautical miles (370 kilometres; 230 miles) of the radar antenna. They may also use radar data to control when it provides a better 'picture' of the traffic, or when it can fill in a portion of the area not covered by the long range radar. In the U.S. system, at higher altitudes, over 90% of

1111-414: A large amount of data being available to the controller. To address this, automation systems have been designed that consolidate the radar data for the controller. This consolidation includes eliminating duplicate radar returns, ensuring the best radar for each geographical area is providing the data, and displaying the data in an effective format. Centres also exercise control over traffic travelling over

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1212-556: A long-range radar system at a cost of €10 million for the Irish Aviation Authority and Irish Defence Forces (military) to keep track of covert aircraft flying in Irish-controlled airspace, including military aircraft that do not file a flight plan and do not have their transponders switched on. Minister for Defence Simon Coveney said the increased surveillance capability would give better coverage of

1313-447: A lower level of flying skill on the part of the pilot, and meteorological conditions in which a pilot can see and avoid other aircraft. As its name suggests, SVFR is a special infrequently-used set of rules. For the purposes of separation, controllers consider SVFR to be the same as IFR. Airspace exists in seven classes , A to G, in decreasing order of air traffic control regulation. Classes A to E are controlled airspace and class G

1414-543: A minimum angle. Other lateral separation may be defined by the geography of pre-determined routes, for example the North Atlantic Track system. If two aircraft are not laterally separated, and are following tracks within 45 degrees of each other (or the reciprocal), then they are said to be following the same route and some form of longitudinal separation must exist. Longitudinal separation can be based upon time or distance as measure by DME. The golden rule

1515-404: 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. Air traffic controllers apply rules, known as separation minima , to do this. Pairs of aircraft to which these rules have been successfully applied are said to be separated : the risk of these aircraft colliding

1616-746: A new area control centre into service at the London Area Control Centre (LACC) at 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. Some tools are available in different domains to help

1717-472: A number of airlines, particularly in Europe, have started using alphanumeric call signs that are not based on flight numbers (e.g. DLH23LG, spoken as Lufthansa -two-three-lima-golf , to prevent confusion between incoming DLH23 and outgoing DLH24 in the same frequency). Additionally, it is the right of the air traffic controller to change the 'audio' call sign for the period the flight is in his sector if there

1818-546: A practical example of the rules, US FAA rules are published in the FAA Order 7110.65 ; the rules are complicated, and they allow different separation distances (from 3NM to 10NM) depending on the aircraft, distance from radar antenna, type of radar used, flight level , etc. In certain special cases, controllers may reduce separation below the usually required minima. Aerodrome or "Tower" controllers work in tall towers with large windows allowing them, in good weather, to see

1919-510: A radar control facility that is associated with that specific airport. In most countries, this is referred to as terminal control and abbreviated to TMC; in the U.S., it is referred to as a 'terminal radar approach control' or TRACON. While every airport varies, terminal controllers usually handle traffic in a 30-to-50-nautical-mile (56 to 93 km; 35 to 58 mi) radius from the airport. Where there are many busy airports close together, one consolidated terminal control centre may service all

2020-428: A seamless manner; in other cases, local agreements may allow 'silent handovers', such that the receiving centre does not require any co-ordination if traffic is presented in an agreed manner. After the hand-off, the aircraft is given a frequency change, and its pilot begins talking to the next controller. This process continues until the aircraft is handed off to a terminal controller ('approach'). Since centres control

2121-520: A single hole in a line of thunderstorms. Occasionally, weather considerations cause delays to aircraft prior to their departure as routes are closed by thunderstorms. Much money has been spent on creating software to streamline this process. However, at some ACCs, air traffic controllers still record data for each flight on strips of paper and personally coordinate their paths. In newer sites, these flight progress strips have been replaced by electronic data presented on computer screens. As new equipment

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2222-441: A smaller aircraft following larger aircraft. It is a common misconception that air traffic controllers keep all aircraft separated. Whether aircraft actually need separating depends upon the class of airspace in which the aircraft are flying, and the flight rules under which the pilot is operating the aircraft. As stated by the U.S. FAA, The pilot has the ultimate responsibility for ensuring appropriate separations and positioning of

2323-451: 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

2424-415: A two or three 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

2525-419: A unique callsign ( Mode S ). Certain types of weather may also register on the radar screen. These inputs, added to data from other radars, are correlated to build the air situation. Some basic processing occurs on the radar tracks, such as calculating ground speed and magnetic headings. Usually, a flight data processing system manages all the flight plan related data, incorporating, in a low or high degree,

2626-566: Is uncontrolled airspace . At one end of the scale in classes A and B airspace, all aircraft must be separated from each other. At the other end of the scale in class G airspace there is no requirement for any aircraft to be separated from each other. In the intermediate classes some aircraft are separated from each other depending on the flight rules under which the aircraft are operating. For example, in class D airspace, IFR aircraft are separated from other IFR aircraft, but not from VFR aircraft, nor are VFR aircraft separated from each other. Between

2727-541: Is a risk of confusion, usually choosing the aircraft registration identifier instead. Many technologies are used in air traffic control systems. Primary and secondary radars are used to enhance a controller's situational awareness within their assigned airspace; all types of aircraft send back primary echoes of varying sizes to controllers' screens as radar energy is bounced off their skins, and transponder -equipped aircraft reply to secondary radar interrogations by giving an ID ( Mode A ), an altitude ( Mode C ), and / or

2828-416: Is a wide range of capabilities on these systems as they are being modernised. Older systems will display a map of the airport and the target. Newer systems include the capability to display higher-quality mapping, radar targets, data blocks, and safety alerts, and to interface with other systems, such as digital flight strips. Air control (known to pilots as tower or tower control ) is responsible for

2929-510: Is also coordinated with the relevant radar centre or flow control unit and ground control, to ensure that the aircraft reaches the runway in time to meet the time restriction provided by the relevant unit. At some airports, clearance delivery also plans aircraft push-backs and engine starts, in which case it is known as the ground movement planner (GMP): this position is particularly important at heavily congested airports to prevent taxiway and aircraft parking area gridlock. Flight data (which

3030-464: 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, 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

3131-399: Is an event in which two or more aircraft experience a loss of minimum separation. This does not in itself suggest that the aircraft are at any risk of collision. However, the separation minima are set for risk mitigation and therefore it is central to a controller's job to prevent this situation from occurring. Conflicts are detected by data assistants, who report them to the actual controllers;

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3232-438: Is applied by a controller observing that the radar returns from the two aircraft are a certain minimum horizontal distance away from each other, as observed on a suitably calibrated radar system. The actual distance used varies: 5NM (9.26km) is common in en route airspace, 3 NM is common in terminal airspace at lower levels. On occasion, 10 NM may be used, especially at long range or in regions of less reliable radar coverage. As

3333-402: Is brought in, more and more sites are upgrading away from paper flight strips. Constrained control capacity and growing traffic lead to flight cancellation and delays : By then the market for air-traffic services was worth $ 14bn. More efficient ATC could save 5-10% of aviation fuel by avoiding holding patterns and indirect airways . The military takes 80% of Chinese airspace, congesting

3434-518: Is required to have clearance from ground control. This is normally done via VHF / UHF radio, but there may be special cases where other procedures are used. Aircraft or vehicles without radios must respond to ATC instructions via aviation light signals , or else be led by official airport vehicles with radios. People working on the airport surface normally have a communications link through which they can communicate with ground control, commonly either by handheld radio or even cell phone . Ground control

3535-480: Is responsible for the airport movement areas, as well as areas not released to the airlines or other users. This generally includes all taxiways, inactive runways, holding areas, and some transitional aprons or intersections where aircraft arrive, having vacated the runway or departure gate. Exact areas and control responsibilities are clearly defined in local documents and agreements at each airport. Any aircraft, vehicle, or person walking or working in these areas

3636-438: Is routinely combined with clearance delivery) is the position that is responsible for ensuring that both controllers and pilots have the most current information: pertinent weather changes, outages, airport ground delays / ground stops, runway closures, etc. Flight data may inform the pilots using a recorded continuous loop on a specific frequency known as the automatic terminal information service (ATIS). Many airports have

3737-646: Is the Maastricht Upper Area Control Centre (MUAC), founded in 1972 by Eurocontrol, and covering Belgium, Luxembourg, the Netherlands, and north-western Germany. In 2001, the European Union (EU) aimed to create a 'Single European Sky', hoping to boost efficiency and gain economies of scale. The primary method of controlling the immediate airport environment is visual observation from the airport control tower. The tower

3838-535: Is the 10-minute rule: no two aircraft following the same route must come within 15 minutes flying time of each other. In areas with good navaid cover this reduces to 10 minutes; if the preceding aircraft is faster than the following one then this can be reduced further depending on the difference in speed. Aircraft whose tracks bisect at more than 45 degrees are said to be crossing, in this case longitudinal separation cannot be applied as it will not be very long before lateral separation will exist again. Radar separation

3939-606: 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. Clearance delivery, or, at busy airports, ground movement planner (GMP) or traffic management coordinator (TMC) will, if necessary, coordinate with the relevant radar centre or flow control unit to obtain releases for aircraft. At busy airports, these releases are often automatic, and are controlled by local agreements allowing 'free-flow' departures. When weather or extremely high demand for

4040-408: Is therefore remote. If separation is lost between two aircraft, they are said to be in a conflict . When an aircraft passes behind or follows another aircraft, wake turbulence minima are applied due to the effect of the wingtip vortices of the preceding aircraft on the following aircraft. These minima vary depending on the relative size of the two aircraft. This is acute on final approach with

4141-413: Is typically a tall, windowed structure, located within the airport grounds. The air traffic controllers , 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 5 to 10 nautical miles (9 to 19 kilometres ; 6 to 12 miles ), depending on

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4242-466: Is vital to the smooth operation of the airport because this position impacts the sequencing of departure aircraft, affecting the safety and efficiency of the airport's operation. Some busier airports have surface movement radar (SMR), such as ASDE-3, AMASS, or ASDE-X , designed to display aircraft and vehicles on the ground. These are used by ground control as an additional tool to control ground traffic, particularly at night or in poor visibility. There

4343-540: The Atlantic airspace over which the IAA has responsibility for civil and military aircraft. The safety and regulatory division and the air navigation services of the IAA were split into two separate organisations on 30 April 2023. The Safety and Regulatory Division of the IAA merged with the Commission for Aviation Regulation to become the new Irish Aviation Authority. The air navigation service provider functions of

4444-903: The Federal Aviation Administration to the airline industry. The National Business Aviation Association (NBAA), the General Aviation Manufacturers Association, the Aircraft Owners and 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

4545-566: The U.S. Army to direct and track the movements of reconnaissance aircraft . Over time, the AMRS morphed into flight service stations . 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

4646-604: The ANSP (Air Navigation Service Provider) section of the IAA became a separate organisation, Irish Air Navigation Service , trading as AirNav Ireland or AirNav na hÉireann , which now provides air traffic management and aeronautical communications services in Irish controlled airspace. From 30 April 2023, the IAA (merged with the Commission for Aviation Regulation ) remains as the civil aviation authority of Ireland, retaining

4747-734: The ATC from Prestwick . Shannon Aeradio, as it is known, is based in Ballygirreen, Newmarket-on-Fergus, County Clare. In October 2009, it was announced that the regulatory aspects of the IAA's remit would be transferred to the Dublin Transport Authority, later renamed the National Transport Authority . However, this plan never went ahead. In July 2015, the Irish government revealed plans to purchase

4848-531: 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. Single air-traffic control services in continent-sized America and China does not alleviate congestion. Eurocontrol tries to reduce delays by diverting flights to less busy routes: flight paths across Europe were redesigned to accommodate

4949-427: The IAA were transferred to a new ANSP called AirNav Ireland. Air traffic control 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

5050-407: The U.S. airspace is covered by radar, and often by multiple radar systems; however, coverage may be inconsistent at lower altitudes used by aircraft, due to high terrain or distance from radar facilities. A centre may require numerous radar systems to cover the airspace assigned to them, and may also rely on pilot position reports from aircraft flying below the floor of radar coverage. This results in

5151-492: The U.S., TRACONs are additionally designated by a three-digit alphanumeric code. For example, the Chicago TRACON is designated C90. Air traffic control also provides services to aircraft in flight between airports. Pilots fly under one of two sets of rules for separation: visual flight rules (VFR), or instrument flight rules (IFR). Air traffic controllers have different responsibilities to aircraft operating under

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5252-585: The US at a specific airport, opened in Cleveland in 1930. Approach / 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. Currently in

5353-601: The US, the Federal Aviation Administration (FAA) operates 22 Air Route Traffic Control Centers . 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. In 1960, Britain, France, Germany, and the Benelux countries set up Eurocontrol , intending to merge their airspaces. The first and only attempt to pool controllers between countries

5454-465: The active runway surfaces. Air control gives clearance for aircraft takeoff or landing, whilst ensuring that prescribed runway separation will exist at all times. If the air controller detects any unsafe conditions, a landing aircraft may be instructed to ' go-around ', and be re-sequenced into the landing pattern. This re-sequencing will depend on the type of flight, and may be handled by the air controller, approach, or terminal area controller. Within

5555-471: The air by holding over specified locations until they may be safely sequenced to the runway. Up until the 1990s, holding, which has significant environmental and cost implications, was a routine occurrence at many airports. Advances in computers now allow the sequencing of aircraft hours in advance. Thus, aircraft may be delayed before they even take off (by being given a 'slot'), or may reduce speed in flight and proceed more slowly thus significantly reducing

5656-419: The air controllers aware of the traffic flow towards their runways to maximise runway utilisation through effective approach spacing. Crew resource management (CRM) procedures are often used to ensure this communication process is efficient and clear. Within ATC, it is usually known as 'team resource management' (TRM), and the level of focus on TRM varies within different ATC organisations. Clearance delivery

5757-900: The air traffic control system are primarily related to the volume of air traffic demand placed on the system, and weather. Several factors dictate the amount of traffic that can land at an airport in a given amount of time. Each landing aircraft must touch down, slow, and exit the runway , before the next aircraft crosses the approach end of the runway. This process requires at least one, and up to four minutes for each aircraft. Allowing for departures between arrivals, each runway can thus handle about 30 aircraft arrivals per hour. A large airport with two arrival runways can handle about 60 arrivals per hour in good weather. Problems arise when airlines schedule more arrivals into an airport than can be physically handled, or when delays elsewhere cause groups of aircraft – that would otherwise be separated in time – to arrive simultaneously. Aircraft must then be delayed in

5858-454: The air, a ground delay programme may be established, delaying aircraft on the ground before departure due to conditions at the arrival airport. In Area Control Centres, a major weather problem is thunderstorms , which present a variety of hazards to aircraft. Airborne aircraft will deviate around storms, reducing the capacity of the en-route system, by requiring more space per aircraft, or causing congestion, as many aircraft try to move through

5959-412: The aircraft approaches its destination, the centre is responsible for issuing instructions to pilots so that they will meet altitude restrictions by specific points, as well as providing many destination airports with a traffic flow, which prohibits all of the arrivals being 'bunched together'. These 'flow restrictions' often begin in the middle of the route, as controllers will position aircraft landing in

6060-400: The aircraft flying in the vicinity of the aerodrome, unless the aircraft is not in sight from the tower (e.g. a helicopter departing from a ramp area). Also, aircraft in the vicinity of an aerodrome tend to be flying at lower speeds. Therefore, if the aerodrome controller can see both aircraft, or both aircraft report that they can see each other, or a following aircraft reports that it can see

6161-432: The aircraft in the terminal area to avoid the wake turbulence created by a preceding aircraft . There are three sets of flight rules under which an aircraft can be flown: Public transport flights are almost exclusively operated under IFR, as this set of rules allows flight in regions of low visibility (e.g. cloud). On the other hand, a large amount of private flying in light aircraft is done under VFR since this requires

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6262-481: The aircraft operator, and identical call sign might be used for the same scheduled journey each day it is operated, even if the departure time varies a little across different days of the week. The call sign of the return flight often differs only by the final digit from the outbound flight. Generally, airline flight numbers are even if east-bound, and odd if west-bound. In order to reduce the possibility of two call signs on one frequency at any time sounding too similar,

6363-427: The aircraft which should not be infringed upon by any other aircraft. A local conflict occurs if two or more aircraft pass a certain given point (in nearly all cases a certain town) . A local conflict occurs, if at least one of the following conditions are met: An opposite conflict occurs if two aircraft are flying towards each other from opposing directions. Looking at the information on the flight progress strips ,

6464-628: The aircraft. 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. In practice, the native language for a region is used; however, English must be used upon request. In 1920, Croydon Airport near London, England, was the first airport in the world to introduce air traffic control. The 'aerodrome control tower'

6565-424: 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. 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

6666-543: The airports. The airspace boundaries and altitudes assigned to a terminal control centre, which vary widely from airport to airport, are based on factors such as traffic flows, neighbouring airports, and terrain. A large and complex example was the London Terminal Control Centre (LTCC), which controlled traffic for five main London airports up to an altitude of 20,000 feet (6,096 metres) and out to

6767-578: The amount of holding. 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

6868-470: The broad-scale dissemination of air traffic data. The Aircraft Situational Display to Industry ( ASDI ) system now conveys up-to-date flight information to the airline industry and the public. Some companies that distribute ASDI information are Flightradar24 , FlightExplorer, FlightView, and FlyteComm. Each company maintains a website that provides free updated information to the public on flight status. Stand-alone programmes are also available for displaying

6969-528: The centre provides a clearance. Centre controllers are responsible for issuing instructions to pilots to climb their aircraft to their assigned altitude, while, at the same time, ensuring that the aircraft is properly separated from all other aircraft in its immediate area. Additionally, the aircraft must be placed in a flow consistent with the aircraft's route of flight. This effort is complicated by crossing traffic, severe weather, special missions that require large airspace allocations, and traffic density. When

7070-502: The characteristics of the job. Surveillance displays are also available to controllers at larger airports to assist with controlling air traffic. Controllers may use a radar system called secondary surveillance radar for airborne traffic approaching and departing. These displays include a map of the area, the position of various aircraft, and data tags that include aircraft identification, speed, altitude, and other information described in local procedures. In adverse weather conditions,

7171-603: The controller further: In the United States, some alterations to traffic control procedures are being examined: In Europe, the Single European Sky ATM Research (SESAR) 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. In April 2019,

7272-431: The data assistants suggest how to solve the conflict, but the controller is not obligated to follow the suggested instructions. A conflict occurs when the distance between aircraft in flight violates a defining criterion, usually considered as 5 nautical miles (9 km) of horizontal and/or 1,000 ft (300 m) of vertical separation. These distances define an aircraft's protected zone, a volume of airspace surrounding

7373-472: The different sets of rules. While IFR flights are under positive control, in the US and Canada, VFR pilots can request 'flight following' (radar advisories), which provides traffic advisory services on a time permitting basis, and may also provide assistance in avoiding areas of weather and flight restrictions, as well as allowing pilots into the air traffic control system prior to the need to a clearance into certain airspace. Throughout Europe, pilots may request

7474-598: The equivalent term air route traffic control center. Each centre is responsible for a given flight information region (FIR). Each flight information region typically covers many thousands of square miles of airspace, and the airports within that airspace. Centres control IFR aircraft from the time they depart from an airport or terminal area's airspace, to the time they arrive at another airport or terminal area's airspace. Centres may also 'pick up' VFR aircraft that are already airborne, and integrate them into their system. These aircraft must continue under VFR flight rules until

7575-565: The flow of traffic in the air, and provide information and other support for pilots. Personnel of air traffic control monitor aircraft location in their assigned airspace by radar , and communicate with the pilots by radio . To prevent collisions, ATC enforces 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 private , military , and commercial aircraft operating within its airspace; not just civilian aircraft. Depending on

7676-523: The following provides a general concept of the delegation of responsibilities within the air traffic control tower environment. 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. Displays for the air traffic controllers may be live video, synthetic images based on surveillance sensor data, or both. Ground control (sometimes known as ground movement control , GMC)

7777-432: The geographic location of airborne instrument flight rules (IFR) air traffic anywhere in the FAA air traffic system. Positions are reported for both commercial and general aviation traffic. The programmes can overlay air traffic with a wide selection of maps such as, geo-political boundaries, air traffic control centre boundaries, high altitude jet routes, satellite cloud and radar imagery. The day-to-day problems faced by

7878-427: The ground and clearance for approach to an airport. Controllers adhere to a set of separation standards that define the minimum distance allowed between aircraft. These distances vary depending on the equipment and procedures used in providing ATC services. En-route air traffic controllers work in facilities called air traffic control centres, each of which is commonly referred to as a 'centre'. The United States uses

7979-408: The information of the track once the correlation between them (flight plan and track) is established. All this information is distributed to modern operational display systems , making it available to controllers. The Federal Aviation Administration (FAA) has spent over US$ 3 billion on software, but a fully automated system is still yet to be achieved. In 2002, the United Kingdom commissioned

8080-571: 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. This technology is currently used in portions of the North Atlantic and the Pacific by a variety of states who share responsibility for the control of this airspace. 'Precision approach radars' (PAR) are commonly used by military controllers of air forces of several countries, to assist

8181-424: 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'. This abbreviation is only allowed after communications have been established in each sector. Before around 1980, International Air Transport Association (IATA) and ICAO were using

8282-483: The name Irish Aviation Authority. The authority controlled air traffic for the three major international airports in Ireland. The smaller airports such as Ireland West Airport provide their own approach and aerodrome service. In recent years, the authority has invested more than €115 million in air traffic control systems. This includes a new air traffic control centre (ATCC) at Ballycasey Cross , Shannon. Built on

8383-530: The new airport in Istanbul, which opened in April, but the extra capacity will be absorbed by rising demand for air travel. Well-paid jobs in western Europe could move east with cheaper labour. 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. French controllers spent

8484-438: The overall capacity for any given route. The North Atlantic Track system is a notable example of this method. 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'

8585-482: The pilot in final phases of landing in places where instrument landing system and other sophisticated airborne equipment are unavailable to assist the pilots in marginal or near zero visibility conditions. This procedure is also called a 'talk-down'. 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,

8686-419: The preceding one, controllers may reduce the standard separation to whatever is adequate to prevent a collision. Under its SESAR project, Eurocontrol is optimizing the slack of the separation, reducing it from 3 to 2.5 nmi (5.6 to 4.6 km): a simulation increased throughput by up to 14% at Zurich 's Runway 14, which cannot have any high-speed exit , inducing a longer runway occupancy. A conflict

8787-544: The presence of traffic and conditions that lead to loss of minimum separation. Beyond runway capacity issues, the weather is a major factor in traffic capacity. Rain, ice , snow, or hail on the runway cause landing aircraft to take longer to slow and exit, thus reducing the safe arrival rate, and requiring more space between landing aircraft. Fog also requires a decrease in the landing rate. These, in turn, increase airborne delay for holding aircraft. If more aircraft are scheduled than can be safely and efficiently held in

8888-400: The same destination so that when the aircraft are close to their destination they are sequenced. As an aircraft reaches the boundary of a centre's control area, it is 'handed off' or 'handed over' to the next area control centre . In some cases, this 'hand-off' process involves a transfer of identification and details between controllers so that air traffic control services can be provided in

8989-550: The same two-letter call signs. Due to the larger number of new airlines after deregulation, the ICAO established the three-letter call signs as mentioned above. The IATA call signs are currently used in aerodromes on the announcement tables, but are no longer used in air traffic control. For example, AA is the IATA call sign for American Airlines ; the ATC equivalent is AAL. Flight numbers in regular commercial flights are designated by

9090-420: The separation is still procedural. Lateral separation minima are usually based upon the position of the aircraft as derived visually, from dead reckoning or internal navigation sources, or from radio navigation aids ('beacons'). In the case of beacons, to be separated, the aircraft must be a certain distance from the beacon (measured by time or by DME ) and their tracks to or from the beacon must diverge by

9191-634: The standard 2,000 feet (600 m). RVSM airspace encompasses Europe, North America, parts of Asia and Africa and both the Pacific and Atlantic oceans. In areas where RVSM capabilities exist, 1,000 feet of vertical separation may be utilized up to FL410 (41,000 ft) , and 2,000 between FL410 and FL600 (60,000 ft). 5,000 ft vertical separation must be applied to military aircraft above FL600, RVSM or not. "MARSA" separation can be applied by military aircraft, which overrides all of these rules. Under MARSA conditions (Military Assumes Responsibility for Separating Aircraft), Air traffic controllers protect only

9292-713: The surface and an altitude of 29,000 feet (8,800 m), no aircraft should come closer vertically than 300 metres, unless some form of horizontal separation is provided (Note: for countries that measure altitude in feet , a 1,000 feet minimum is observed rather than the 984.252 feet found in 300 meters). Above 29,000 feet (8,800 m), no aircraft shall come closer than 600 m (or 2,000 feet), except in airspace where Reduced Vertical Separation Minima (RVSM) can be applied. In certain airspace, between 29,000 and 41,000 feet (12,500 m), pairs of aircraft equipped with more modern altimeter and autopilot systems can be vertically separated by minimum of 1,000 feet (300 m) rather than

9393-418: The thin corridors open to airliners. The United Kingdom closes its military airspace only during military exercises. A prerequisite to safe air traffic separation is the assignment and use of distinctive call signs . These are permanently allocated by ICAO on request, usually to scheduled flights , and some air forces and other military services for military flights . There are written call signs with

9494-728: The tower controllers may also use surface movement radar (SMR), surface movement guidance and control system (SMGCS), or advanced surface movement guidance and control system (ASMGCS) to control traffic on the manoeuvring area (taxiways and runways). The areas of responsibility for tower controllers fall into three general operational disciplines: local control or air control, ground control, and flight data / clearance delivery. Other categories, such as airport apron control, or ground movement planner, may also exist at extremely busy airports. While each tower may have unique airport-specific procedures, such as multiple teams of controllers ( crews ) at major or complex airports with multiple runways,

9595-452: The tower on the airport and vector inbound aircraft to a position from where they can land visually. At some of these airports, the tower may provide a non-radar procedural approach service to arriving aircraft handed over from a radar unit before they are visual to land. Some units also have a dedicated approach unit, which can provide the procedural approach service either all the time, or for any periods of radar outage for any reason. In

9696-432: The tower, a highly disciplined communications process between the air control and ground control is an absolute necessity. Air control must ensure that ground control is aware of any operations that will impact the taxiways, and work with the approach radar controllers to create gaps in the arrival traffic; to allow taxiing traffic to cross runways, and to allow departing aircraft to take off. Ground control needs to keep

9797-425: 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

9898-472: The use of radar to provide air traffic control using procedural separation minima . In procedural control, any period during which two aircraft are not vertically separated is said to be "level change". In some cases, procedural separation minima are provided for use with radar assistance, however it is important not to get this mixed up with radar separation as in the former case the radar need not necessarily be certified for use for radar separation purposes,

9999-557: The world's ocean areas. These areas are also flight information regions (FIRs). Because there are no radar systems available for oceanic control, oceanic controllers provide ATC services using procedural control . These procedures use aircraft position reports, time, altitude, distance, and speed, to ensure separation. Controllers record information on flight progress strips , and in specially developed oceanic computer systems, as aircraft report positions. This process requires that aircraft be separated by greater distances, which reduces

10100-496: 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 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

10201-414: Was a wooden hut 15 feet (5 metres) high with windows on all four sides. It was commissioned on 25 February 1920, and provided basic traffic, weather, and location information to pilots. 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

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