Improved United Kingdom Air Defence Ground Environment

By the mid-1960s, with the Soviet Union reaching strategic parity with NATO, such an attack no longer seemed likely; it was assumed a war would have a protracted conventional stage, perhaps never going nuclear.

It replaced Linesman's fixed communication links with a packet switching network sending data to multiple command centres around the country.

Radar sites had the ability to control interceptions by themselves, while the overall recognised air picture was compiled and directed at Strike Command headquarters.

It was not declared operational until 1 June 1993, six years late, by which time the ending of the Cold War had led to a loss in interest in the programme.

In 1957, Duncan Sandys introduced his Defence White Paper which, among other topics, considered the effect of the introduction of ballistic missiles on the UK's defensive posture.

After rapidly completed negotiations, the United States agreed to move one of their new BMEWS radars to the UK, initially to Scotland, but later to Yorkshire at RAF Fylingdales where it could be better protected.

Studies began to see if Plan Ahead could be combined with the air traffic control (ATC) network, allowing both users to share their radar coverage.

[11] In the era of a three-day war and attacks by hydrogen bombs, any attempt to harden the centre seemed futile, so the building was located aboveground.

[12] The RAF was adamantly opposed to this change, stating that control over the interceptor force should take place at the radar stations so the failure of the centralized centre would not render the system useless at a stroke.

Much of the blame was laid on Plessey, whose previous experience in telephone switching left them unprepared for the level of programming support needed.

[19] In July 1964, the US Joint Chiefs of Staff admitted that the Soviet nuclear forces would survive in enough number to guarantee their own massive retaliation.

[10] Moreover, new Soviet aircraft with longer range allowed the UK to be approached from across the North Atlantic, where radars had been run down in keeping with Linesman's tripwire concept.

[27] In September 1971, Air Commander John Nicholls published a report on Linesman outlining its many problems, notably the lack of coverage in the north and south, and its inability to deal with low-flying targets.

Strike Command noted that if the track extraction was being carried out at the radar stations, the resulting information, essentially an ID number, location and direction, could easily be sent in digital format over conventional telephone lines or narrow-band microwave links, as was being done in NADGE.

Finally, they called for the replacement of the huge and costly radars like the AMES Type 85 with a greater number of simpler and cheaper systems.

[34] Data from NADGE, Royal Navy ships and newly purchased airborne radar aircraft would also be injected into the network by radio links, and distributed over various telecommunications systems.

[31] On 18 December 1972, the Air Force Board accepted the reports and decided "that Phase 1 of the LINESMAN project should be completed but that, after commissioning, the L1 building should be operated and manned on only a limited basis ...

Emphasis was to be placed on keeping expenditure to a minimum and high priority was to be given to the development of an alternative - less vulnerable - air defence system.

[36] With the acceptance of the need for a new system, in 1972 Strike Command formed the Air Defence Environment Team, or ADET, to define a formal proposal and liaise with industry during construction.

Two major bids were received, and in September 1980 the contract was won by the newly formed UKADGE Systems Limited, a consortium of Hughes Aircraft, Marconi and Plessey.

The ADOCs were in charge of the overall command of the defence response and the maintenance of the recognized air picture, which would be fed data on civilian flights and jammer activity from the existing L1 site.

[45] The L-band radar component was quickly awarded to the Marconi Martello system, a recently introduced design of some sophistication, while the NATO-funded sites would make use of the US-built AN/TPS-59 in its GE592 guise.

[42] The selection of the corresponding S-band system was more contentious, with Plessey offering to merge their somewhat dated AR-3D receiver and display electronics with a new transmitter and antenna from ITT-Gilfillan to produce the AR-320, which competed against the Hughes Air Defense Radar.

Political wrangling, and Hughes' self-interest, delayed the selection for months, before it was ultimately won by the AR-320 based on hopes for additional export sales to NATO.

Additionally, a requirement for decoy transmitters was added, both to further confuse jammer systems as well as to provide multiple targets to anti-radiation missiles.

[40] Meanwhile, the TPS-592 radars, which should have been easily adapted from their US counterparts, ran into extensive delays due to the need to meet more stringent operational requirements, and ultimately took five years to pass tests.

[40] At least some of the problem was identified as the system using three different programming languages, CORAL, FORTRAN and RTL/2, which led to a study into the feasibility of replacing all of these with the newly introduced Ada.

[47] Under Project Cheek, formalized as Air Staff Requirement 894, a Thorn-EMI system would receive data from either aircraft and display it on a separate console.

In June 1989, the MoD formed a new project known as TRIAD, short for Techniques for Realizing an Integrated Air Defence, in an effort to get the system up and running as quickly as possible.

Plessey, Ferranti and Thorn-EMI all won contracts to study the idea of connecting new processors to the ICCS network through a public interface.