History of air traffic control in the United Kingdom

The history of air traffic control in the United Kingdom began in the late 1950s, and early 1960s, when an integrated and coordinated system began, once radar had become sufficiently advanced to allow this.

London Airport
On 15 July 1919, the world's first commercial flight occurred, when Henry Shaw (1892-1977) piloted a de Havilland DH.9 for Aircraft Transport and Travel from Hendon to Le Bourget airfield in Paris. The pilot did not have a passport.

Jimmy Jeffs was the world's first air traffic controller at London Airport on 22 February 1922. The Mayday callsign originated at London Airport in 1921.

The 1922 Picardie mid-air collision started the need for defined air routes.

From 1928, radio signals from Croydon, Pulham St Mary in Norfolk and Lymm in Kent triangulated the position of aircraft; a similar system was set up by Germany in 1940, known as the Battle of the Beams.

On 19 November 1933, the first form of ATC began in the London Zone, with a controlled zone, but no radar

Development of radar
On the evening of 25 February 1935 at Stowe Nine Churches (Upper Stowe) in Northamptonshire, the so-called Daventry experiment took place with Robert Watson-Watt to prove that radar detection of aircraft was possible. Other subsequent technology needed for the wide deployment of radar was coordinated by Sir Edward Fennessy, of 60 Group and Sir Raymund Hart in planning Filter Rooms, at RAF Bawdsey in Suffolk.

The first four radar stations were at Dover in July 1937, Canewdon in August 1937, followed by Great Bromley, and Dunkirk, Kent, with 358-feet masts, fabricated by J. L. Eve Construction.

Ground-controlled interception (GCI) was first developed in the UK during the early part of WWII, at RAF Sopley in Hampshire, close to Bournemouth. Development of the system began in October 1940, and the first ground-controlled interception took place on 1 January 1941 with the Bristol Beaufighter at RAF Middle Wallop, and the call sign Starlight.

The interception was enabled by 604 Squadron. The Beaufighter R2098 NG-H, equipped with the AI Mark IV radar had made the first interception with AI radar at 00.35 on 20 November 1940, thanks to radar operator Sgt John Phillipson, destroying a Junkers Ju 88A, B3-YL, of III./KG 54 from Évreux-Fauville Air Base; Birmingham had been heavily bombed that night by 439 German aircraft, guided by KG 100; the Ju 88 pilot Unteroffizier Franz Sondermeier baled out.

The Beaufighter had four Hispano-Suiza HS.404 20mm cannon in the nose of the aircraft (the Messerschmitt Bf 109 had one), so if any enemy aircraft could be caught at close range, by its airborne radar, few German aircraft would survive. Although the rate of Luftwaffe combat losses, detected by airborne radar, markedly increased throughout the first half of 1941, only three German bombers destroyed over Britain in February 1941, around 50 in April and 102 in May. The Luftwaffe campaign would abruptly stop in the second week of May 1941.

From late 1941, GCI would be carried out by the AMES Type 7 radar, which provided a 360 degrees view; such radar was developed at the Telecommunications Research Establishment (TRE).

The other GCI units were at Orby in east Lincolnshire, Waldringfield in east Suffolk, Willesborough in Kent next to the present M20, Durrington, West Sussex and Avebury, by end of January 1941, being fitted from June 1941 with the AMES Type 7.

Precision Approach Radar began around 1944, being tested at Hinton-in-the-Hedges Airfield, and RAF Honiley, known as AN/MPN-1.

As part of the Telecommunications Flying Unit, on 16 January 1945 at RAF Defford in Worcestershire, Boeing 247 DZ203 made the first automatic approach and landing.

After the war BEA planned to navigate its aircraft with the GEE system, across Scotland and Northern Ireland.

In February 1946 there was an international conference at the headquarters of RAF Transport Command, that discussed new radar, orbit meters for orbits, and the Rebecca/Eureka transponding radar.

Integration
ILS was introduced on 1 March 1950, replacing SBA, or Standard Beam Approach. Stansted had the Civil Aviation Flying Unit, from 1950. The discipline of holding patterns was established at Stansted, and at Bournemouth, and conducted flights to calibrate VOR-DME transmitters.

From 14 April 1950 the ATC centre at Raigmore moved to Prestwick; Raigmore had looked after the Northern Scottish FIR, which merged with the Central Scottish FIR.

On Wednesday 18 June 1958, a £5m plan for coordinating air traffic control was announced. Four new radar centres would be built; previous to this, ATC personnel received aircraft positional information over the radio from pilots, not from any radar. The UK Air Traffic Service began in September 1959; it controlled air movements above 25,000 ft.

The USA had created its Federal Aviation Administration (FAA) also in 1958.

Routes
The first longer-range 750kW radar opened at London Airport on 22 February 1950, with the first airway expected to start from early June 1950; it could detect four-engined aircraft at 130 miles, at 20,000 ft, and at 90 miles, at 10,000 ft. A trial system had begun in May 1949. It was known as London Radar, and was the first of its type in the world. London Radar had two AN/CPS-1 sets, and a Marconi S-232 50cm radar, with a 70-mile range.

Until better electronics had been installed, ground-control approaches at airports, in bad weather, were the scenes of a series of terrible accidents in the 1950s.

Upper airspace routes, known as airways, were created in the early 1950s.

In the first phase of airways
 * Green One opened on 1 August 1950, from the Irish Sea - Strumble Head - Bristol - London.; it was ten miles wide, 5,000 to 11,000 ft

In the second phase of airways on 15 February 1951
 * Green One, was extended eastwards via North Foreland to a point 21 miles off the east coast, at Koksijde (Coxyde), in Belgium, for London to Brussels traffic
 * Amber One, Daventry - Dunsfold - Dieppe - Paris, later extended to Manchester
 * Amber Two Paris - Abbeville - Brookmans Park - Daventry
 * Red One, Dunsfold - North Foreland - Amsterdam
 * Blue One, Bletchley - Watford - Crowborough
 * Red Two, Woodley - Epsom - Kent

In the third phase of airways, around June 1951
 * Amber One was extended northwards via Manchester and Liverpool to Prestwick and Glasgow
 * Green Two, Dublin - Liverpool - north west Europe
 * Red Three, Liverpool - Isle Man - Belfast
 * Blue Two, Belfast - Prestwick - Glasgow

Norway, Sweden and the US Zone of Germany also had airways, but the UK was the furthest in development. The rest of Europe was expected to have airways by 1 September 1952.

Amber One had beacons at New Galloway and Stonehouse, South Lanarkshire; another beacon further south was Dean Cross, between Plumbland and Gilcrux in north-west Cumbria.

Coordinating organisation
On Monday 10 December 1962, Julian Amery, the Minister for Aviation, announced the new National Air Traffic Control Services, with a central controller. Military air traffic control was controlled by the Military Air Traffic Organisation.

The precision approach radar SLA-3C was ordered from STC in 1962 for civilian airports; the SLA-3B had previously been ordered for military purposes.

In 1963 the RAF ordered the Plessey AR-1 (an airport surveillance radar or ASR) for its terminal approach radar, a 75-mile range.

From 1 July 1965 all new aircraft for British airlines had to be fitted with a flight recorder. BEA chose the Plessey PV710.

The London Terminal Control Centre at RAF West Drayton opened in November 1966, but only received radar coverage in 1971; previous to that, Southern Radar had been headquartered at RAF Sopley in Hampshire from 1959. NATCS, the coordinating organisation, became NATS in April 1972, when it became part of the CAA. Computer flight plans were implemented in 1975.

Civil aviation stopped GEE radars in 1960; the RAF and rescue helicopters continued until 18 April 1969, when GEE was switched off.

The Mediator system started on 1 February 1971 at West Drayton, with the full computer system beginning in the mid-1970s, planned for March 1972. Manchester Airport became the site of the northern radar centre in 1975.

From 12am Friday 26 April 1974, the Lichfield and Hawarden radar sectors were moved from Preston to London; so that London and Prestwick would become the two main radar hubs in the UK.

Prestwick moved into Atlantic House in 1978 (the new centre opened in October 2009). The Manchester centre closed at the end of January 2010.

From the 1980s, ILS was trialled at main airports by the microwave landing system (MLS) as it was thought to be better for bad weather. In April 1978 the ICAO decided to go with a US-Australian system (Time Reference Scanning Beam), than the Doppler Microwave Landing System, of Plessey. ILS had been operating since 1949, and was World War II technology. The MLS allowed various flight paths, whereas ILS only allowed one. MLS was trialled over 12 months, at Stansted, in 1983. It was fitted onto a Hawker Siddeley HS 748 test aircraft, of the CAA. MLS was fitted to runway 28R (called 27R from July 1987, due to movement of the Earth's magnetic field), at Heathrow from November 1986, but was not intended to be implemented across the country until around 1996. Cardiff Airport had MLS, made by Textron Systems next installed, in July 1990, and Aberdeen in July 1991. But by 1994, the FAA had lost interest in MLS, instead choosing satellite-guidance.

At London in 1990, a £22m IBM 4381 computer (IBM 370 architecture) replaced an ageing IBM 9020, which was three IBM 360/65 computers; IBM 9020 was installed around 1974. The Princess Royal opened the new computer on 18 June 1990. London looked after the sectors of Daventry, Pole Hill - Northern England, Bristol - Strumble Head, Irish Sea, Cardiff, Dover - Lydd, Clacton, North Sea and Hurn - Seaford - Worthing.

Aberdeen ATC took over the southern North Sea in the late 1990s from Stansted.

The London Area Control Centre at West Drayton moved to Swanwick, Hampshire at 2.30am on Sunday 27 January 2002, when 29-year-old controller Sarah Harris guided an Airtours International Flight AIH 550 from Gran Canaria Airport at Las Palmas safely into Birmingham Airport. Swanwick had been hoped to open in 1996 and to cost £350m. Swanwick oversaw flights above 20,000 feet, excluding those around Manchester under 21,000 feet and around South East England under 24,500 feet.

Swanwick was intended to replace two sites at West Drayton and Manchester (at Manchester Airport), but the West Drayton centre remained open to oversee London and South East England, and was planned to close in 2007; it closed on 23 November 2007 when around 500 staff moved to Swanwick. NATS also have a technical centre in Whiteley. The RAF 78 Sqn moved to Swanwick from January 2008. Swanwick receives radar information from nine radar sites.

Controllers
ATC personnel were represented by the Institution of Professional Civil Servants, which became Institution of Professionals, Managers and Specialists in 1989.

Training
In the early 1960s, both military and civil radar operators were trained at a joint school at RAF Sopley. Sopley had the joint radar school from October 1960. Sopley remained jointly-run until December 1970, when only military personnel were trained. Sopley closed as radar school around August 1972.

Around sixty countries would send ATC trainees to the College of Air Traffic Control (CATC) in Dorset, including Eastern Europe. The Central Air Traffic Control School RAF trained military ATC personnel from 1963; the first women ATC trainees began later in 1963.

Aircraft movements
There were 372,000 aircraft movements in the UK in 1960, 480,000 in 1962, and 610,000 by 1969.

The Concorde route from Heathrow Airport to Bahrain was the world's first supersonic air transport route.

In the 1980s, south-east England had the busiest airspace in the world, with up to 3,500 aircraft movements per day.

In 2017, NATS handled around 2.5 million flights.

Transatlantic route
There were around two hundred transatlantic aircraft crossings per day in 1961; this was expected to rise to three hundred crossings by 1965.

The UK has the third-largest aviation network after the US and China. Up to 80% of North Atlantic air traffic passes through UK airspace. The Shanwick OCA (Shanwick Oceanic Control) was formed in 1966, and controlled from Prestwick, with two communication towers in southern Ireland and Gloucestershire.

Radar manufacturers
By July 1972, Software Sciences of Hampshire had built the ATC system for the Royal Netherlands Air Force, known as PHAROS - Plan Handling and Radar Operating System. it was built with Nederlandsche Standard Electric and Stansaab Elektronik of Sweden; it worked on two Stansaab Censor 932 computers.

The Portuguese Air Force bought the Watchman. In October 1978, Plessey received a £9m contract to build the radar and flight data processing system for the Austrian FIR.

En-route communications
Early VHF communications with aircraft began around 1950. From Monday 8 May 1950 ATC staff at RAF Prestwick could speak to pilots on 122.1 MHz.

Secondary radar and transponders
From the early 1960s, A.C. Cossor at Harlow claimed to be the only company in Europe making secondary radar.

A meeting in December 1960 between the UK and the US determined how secondary radar would broadly work. By the early 1960s, the USA required US-registered aircraft, flying above 25,000 ft, to have a transponder for secondary surveillance radar. The transponder equipment would cost about £2,000. Without this radar, there was a 1,500 mile radar gap in the North Atlantic. Secondary radar would close this gap. It was hoped to have around eight secondary radar units to cover the UK, with 180 miles range, from around 1963. There would be a maximum of 64 transponder codes available.

Air France and BOAC ordered the Cossor SSR.1251 transponder system for their Boeing 707 aircraft.

By 1 July 1962 all aircraft flying over 25,000 ft in the UK were to have had a transponder fitted. This date was moved to 1 July 1965, then to 1 July 1966, and also applied to Eurocontrol countries. Not enough aircraft had had transponders fitted, and not enough ground radar units had had enough secondary radar added.

A three-day international symposium was held from Monday 23 September 1963 at the Royal Radar Establishment in Worcestershire, with around 250 delegates, to discuss advances in radar such as transponders. It was organised by the Ministry of Aviation and the Electronic Engineering Association.

In April 1965 Russia (through Aviaexport) bought fifty SSR.1600 ATC Airborne Transponders for its Aeroflot fleet, and for manufacturers such as Tupolev, for £80,000. The Concorde team turned down this transponder.

The SSR.2100 transponder was fitted to aircraft such as Concorde, the BAC 1-11, Trident, and the Viscount.

In a £2.75m contract, Plessey supplied the secondary radar system for the new West Drayton site, to operate from mid-1969, on Plessey Digitrace screens.

The Marconi SECAR secondary radar was chosen for Eurocontrol and Brussels Airport.

In 1979 Cossor developed its Adsel transponder system. From 1983, this system was internationally called Mode S (S=selective) to avoid FRUIT (False Returns Unsynchronised with Interrogator Transmissions). It was being trialled in British Midland aircraft.

Cossor largely developed the monopulse system, entering service from the early 1980s. Cossor was the leading company for transponders, right into the 1990s.

The selective Mode S system had been also developed in Worcestershire since the late 1960s. The S band works with 10-cm radar.

Radar stations
Marconi Radar Systems, who built much of the radar, had sites at Bill Quay in Gateshead (mechanical infrastructure), in the north of Leicester (at the junction of Blackbird Road and Anstey Lane), and two large sites in Chelmsford, although much of these radars were for air defence.

The radome canopies were made by English Electric Reinforced Plastic Division at Warton, which became GEC Reinforced Plastics, moving to GEC Engineering at Clayton-le-Moors, north of Accrington, in 1992, later becoming Techbuild Composites in 1994; off the A6185 at junction 7 of the M65.

27 Doppler VOR (VHF omnidirectional range) beacons, costing £3.5m, were built in 1982 by Racial Avionics (former Decca Radar) of New Malden. The first Cossor 20 monopulse SSR 950 were installed in June 1983, replacing Cossor 5G, which were installed in mid 1960s. The first RAF monopulse system was at Scampton in January 1987. A contract for 17 secondary radar sets was given to Marconi Radar Systems in 1985.

In the early 1990s most low-level (up to 100 feet) primary radars for airports and RAF airfields were updated to be the Plessey Watchman, which had around a 50 mile range. Heathrow, Gatwick, Stansted, Manchester and Gatwick were updated in 1988, or early 1989, costing around £2m each. The system had been trialled at Exeter Airport (owned by Devon County Council); Watchman was a much more advanced radar system. East Midlands and Newcastle had the Marconi S511.

The RAF had chosen the Watchman radar system for its airfields in the UK, and overseas, in June 1983. The first to receive the system was RAF Waddington in 1986. Other countries bought the Plessey Watchman as well, including Finland and Spain, for the Palma de Mallorca Airport, which in the month of August, in the 1980s, became the world's busiest airport.

Selex ATCR-33S radars replaced some Plessey Watchman radars across airfields in the early 2010s.

In June 2016 Raytheon received a contract to supply the Mode S monopulse secondary radar to all of NATS 23 radar sites. A Radar Reference Facility was built by Raytheon in Hampshire, to train staff.

The sites are technically referred to as radar heads.

Civilian



 * Allans Hill, Aberdeenshire; situated between New Aberdour and Strichen, with a 9.5-metre tower, had a Plessey Watchman, mainly for helicopters, with a range of 90 miles; planning permission was granted in April 1991, to be built by 1994; 9.5m high, built by Kier Construction, radar by Siemens Plessey Systems, opened February 1994
 * Blackpool, has a Raytheon ASR 10SS; it was fitted with 500 kW 50 cm Marconi Type 264A, when operating the Mediator system, from 1963
 * Burrington, Devon
 * Claxby, also known as Lincoln, in north-east Lincolnshire, has a 250-mile range, on land owned by BT; it replaced the 35-metre steel lattice Claxby Radio Station, run by the Post Office (later BT); would be 42 metres high, to open by 1984; was built directly next to the former GPO lattice tower in late 1983; Claxby, Clee Hill and St Annes radar were sent to the regional ATC centre at Manchester Airport; Claxby was built largely for Lincolnshire's RAF stations
 * In August 1970, a new £150,000 Plessey AR-5 23cm radar for Titterstone Clee Hill, in Shropshire, was to be built by 1971; Clee Hill had RAF radar during World War II, but this site had closed in 1956; the radome was fitted in September 1968, the first radome in the UK; radar information was sent back to London from microwave links at Romsley, Worcestershire, Whichford Hill in the south of Warwickshire, and Christmas Common in the Chilterns, south of the M40; the Plessey DASR-1 en-route system had been there since 1964; the secondary radar had direct connections to Heathrow and Manchester airports, and later to Birmingham in 1979, and East Midlands in 1980
 * Cromer Radar was set up in the late 1980s, with a link to a new air traffic control centre at Stansted; it had Plessey Watchman as its primary radar for the North Sea, often for helicopters travelling to North Sea oil platforms. The RAF and RN also had Cromer as their primary radar; it worked via a travelling-wave tube.
 * Debden, Uttlesford, in Essex, the 23 cm radar has a 160-mile range; planning permission was given in June 1980, being built around 1981; it provided secondary radar for Stansted until 1991; designed by Clifford Tee + Gale, and structural engineering by the Alan Marshall Partnership
 * Great Dun Fell, opened on Friday 7 October 1988, built by Mowlem Regional Construction; primary radar by Hollandse Signaalapparaten B.V. (now called Thales Nederland), it cost £10.5m, it is next to the Pennine Way, east of Milburn, Cumbria
 * Heathrow, the 23 cm radar opened in November 1985 with a 250-mile range, and a 37-metre-high concrete tower, that was built by Fairclough Civil Engineering of Adlington in Lancashire; this has been replaced by a site at Bovingdon, of Dacorum in Hertfordshire around 2012
 * Lowther Hill, at 2,377 ft high near Wanlockhead, on the boundary of Lanarkshire and Dumfriesshire, it was the centre of the Scottish GEE network, which began on 19 August 1948, with slave stations at Craigowl Hill, 1493 feet high, at Tealing, north of Dundee, and Ru Stafnish on Kintyre, 709 feet high, in Argyll and Bute, on the west coast of Scotland;  from May 1950 it had a radio en-route transmitter for contact with pilots in Scotland, in the VHF range from 110 to 130 MHz; chosen in December 1964 totally rebuilt, with Perwinnes Hill, commissioned in 1996,with a 23cm SPR51 Routeman fitted; built by Kier Construction, radar by Siemens Plessey Systems
 * Mount Gabriel, southern Ireland, feeds into LACC
 * Pease Pottage, in the north-east of West Sussex, a 23 cm radar opened in December 1986, on land owned by the Met Office, with a 160-mile range; 37-metres high, with a 15-metre wide dish, it was the Crawley meteorological station, which opened in April 1953; in full operation by 1954; launched four radiosonde weather balloons per day; readings were set to the Met Office in Dunstable
 * Perwinnes Hill, near Aberdeen, for Aberdeen Airport at Dyce, and the helicopters for the North Sea; it had a £325,000 Marconi 264 radar installed on 7 October 1976,  which had been obtained from RAF Sopley; it was improved in the mid-1980s to take radar coverage to 150 miles, with secondary radar, and totally rebuilt in the mid-1990s, with a 19-metre tower, and improved in February 1994, to stop reliance on RRH Buchan for coverage of the North Sea, built by Kier Construction, with radar by Siemens Plessey Systems; the previous 264 radar had been maintained from parts taken from the former Ash and Ventnor radar stations; in the 1980s Aberdeen was the world's biggest heliport
 * Tiree, at Ben Hynish on the Inner Hebrides, it has a 210-nautical mile range; the £8m radar replaced a military radar in 3 cm radar Northern Ireland, and opened in July 1986; a new television transmitter was required to be built as well; the structural engineer was Sir Frederick Snow;  30-metres high, built by Mowlem, of Kilsyth, in a £2.47m contract, completed in March 1985

Military
By 1964, the RAF had four main military radar units.
 * Hack Green, near Baddington in south Cheshire
 * RAF Boulmer, on the Northumberland coast
 * RAF Sopley in south-west Hampshire
 * RAF Bishops Court, near Killard Point, near Downpatrick, County Down, in Northern Ireland; this opened in July 1959.

Former

 * Ash in Kent, the former RAF Ash with Marconi S264A
 * Ventnor, the former RAF Ventnor with Marconi S264A

European central air traffic control
On Thursday 9 June 1960, Britain, France, Belgium, Italy, Luxembourg, West Germany and Holland decided to coordinate air traffic control as jet aircraft were much quicker, to prevent collisions.

Eurocontrol was planned to have jurisdiction over 25,000 ft in the UK, from around 1965.

On Friday 20 December 1968, an agreement was signed to build Europe's first international control centre at Maastricht, to open in 1972, called the Maastricht Automatic Data Processing system or MADAP, which is now called the Maastricht Upper Area Control Centre; for the site, Plessey would build two computers, the controllers' consoles and a radar distribution unit. In 1981, the first computer data link between LATCC at West Drayton and Eurocontrol was established, followed by Brest Airport and Reims in 1986 and Paris in 1987; advanced boundary information (ABI) began in late 1990.

Eurocontrol, established on 1 March 1964, had been initially set up for eventually becoming a Europe-wide full air traffic control system, but individual countries could not together form agreements for this to fully happen; this meant that by the late 1980s Eurocontrol oversaw only flights above 25,000 feet over the Netherlands, Belgium and part of West Germany.

Much of European air traffic control is run on the CIMACT software package. The Single European Sky was created in the late 1990s, being official from 2001.