  Airborne-Early-Warning (AEW) in British military service can trace its roots back to the Second World War. The requirement was realized when the need to protect the Atlantic and Arctic convoys from German warships and long range Focke Wulf Condors became apparent. It had become obvious to all involved that the long-range, land based Chain Home radar stations were unable to provide any 'over the horizon' cover for these essential supply routes. Trials were held with a primative radar installed into a Vickers Wellington bomber. On the whole these test proved unsuccessful and it wouldn't be until 1952 that Britain would have an operational system using equipment supplied by the United States under the Mutual Defense Assistance Program. The Japanese attack on Pearl Harbor made the Americans realize that they also had the requirement for a long range radar system and began development of their own airborne early warning platform. This development program led the General Electric Company to build the AN/APS 20 radar system. Towards the end of the war the U.S. Navy was operating Grumman TBM-3W Avengers fitted with the new radar from its Pacific fleet aircraft carriers. Unfortunately, the system was in its infancy and its effectiveness against the Japanese kamikaze attacks was not as great as had been hoped.
Further development after the war led to an upgraded version of the same radar system being fitted to the Douglas AD-4W Skyraider and it was this aircraft that was delivered to the Fleet Air Arm's (Royal Navy) No.849 Squadron. Designated Skyraider AEW-1 they were deployed onto the Royal Navy's aircraft carriers and remained in operational service until 1960 the same squadron re-equipped with the Fairey Gannet AEW-Mk-3. Though the Gannet was an entirely new airframe, the radar was the same AN/APS 20 model previously fitted to the Skyraider and like the Skyraider, the radar was mounted in a bulbous pod below and just forward of the wing.
The Navy's decision to phase out fixed wing operations during the 1970s led to the task of providing AEW cover to the fleet being transferred to the Royal Air Force. It was decided that twelve, low-hour Shackleton MR-MK-2 airframes would be converted as an interim solution until new; purpose build aircraft could be procured. Again, the same podded AN/APS 20 radar sets were fitted to the Avro designed airframes and No.8 Squadron was declared operational with the Shackleton AEW-2 at RAF Lossemouth, Scotland in 1972.
  Though the RAF was able to provide limited cover for the fleet, the decommissioning of HMS Ark Royal in 1978 and subsequent retirement of the Gannet fleet left the Navy without the ability to provide any long range radar protection when deployed overseas. This situation was highlighted with disastrous consequences when Argentina invaded the Falkland Islands in 1982. In response to the invasion a 'task force' set sail from British waters and headed south without an airborne radar platform to provide any warning of aerial Argentine attacks. The losses of the warships HMS Sheffield, Antelope, Ardent and the civilian container vessel Atlantic Conveyer to French build, sea-skimming Exocet missiles led the Navy to urgently restore its own AEW cover.
Though too late for the conflict in the South Atlantic, this requirement led to the development of thirteen Searchwater radar equipped Sea King HAS-1. The helicopters were upgraded to Mk7 ASaC standard with the Thales Defense Searchwater 2000 radar and Cerberus mission system and remain in service today. In 2010 Augusta-Westland and Thales presented the conceptual design of an AW101 ‘Merlin’ based Airborne Surveillance and Control (ASaC), to replace the Sea King Mk7 ASaC. If the type is selected it will enter service in 2016.
 Throughout the 1970s the requirement to replace the aging Shackletons was gathering pace. Boeing was offering the 707 based E-3A to all NATO countries interested in providing their own AEW/AWACS systems. It was soon realized that the cost of the E-3 was way beyond the budgets of most of the member nations so Boeing then offered the aircraft to the organization as a whole. The inability of the member nations to come to an agreement on how and when this fleet of aircraft would be funded and operated led to the British Government feeling that they had little option but to go it alone. In 1977 an order was placed with Hawker Siddeley for the Nimrod AEW-3. It was also decided that the Nimrod would be made available for sale to NATO to fulfill their requirement once development complete. However, NATO eventually came to a decision and decided to opt for the American solution. Deliveries of the ten E-3A aircraft began to Geilenkirchen, Germany in 1982 and remain in service today.
Unlike the American solution with a single radar antenna mounted in a rotating radome high above the Boeing 707 fuselage. Hawker Siddeley decided that a GEC Avionics two antenna system mounted in the nose and tail of the Nimrod airframe would provide the required solution. The scanners would work together, each providing 180 degrees of uninterrupted coverage of the surrounding airspace. Initial tests of the system were carried out aboard a converted Comet airliner. This test-bed airframe was only fitted with the forward scanner and following its first flight in 1977 development work began on the system. The first of the eleven Nimrod AEW-3s complete with both radar antennas made its maiden flight from Woodford near Manchester in July 1980 and joined the ongoing test program. What followed has filled many volumes but after years of rising costs and delays due to the inability of the radar to work to specification the decision was made in 1987 to cancel its order for the Nimrod solution. It was also announced that Britain was procuring the Boeing E-3D Sentry as it’s Shackleton replacement.
The Shackleton AEW-2 “interim solution” had by now been in service for fifteen years and extensive defense cuts in 1981 saw the fleet cut by 50% to just six aircraft and though professionally maintained to the highest standards the airframes were beginning to show their age. With the delivery of the first Sentry AEW-1 not due until March 1991, No8 Squadrons six veterans had at least another four years of operational service ahead of them. It had been decided that the new AEW fleet would be based at RAF Waddington and to facilitate this in 1990 No8 Squadron was split into two elements. No8 Sqn / North remained in Scotland at RAF Lossiemouth operating the Shackletons while No8 Sqn / South headed across the border and to prepare the Lincolnshire airbase to receive their brand new charges. On 1st July 1991 five of the six remaining Shackletons were flown to Waddington for the ceremony which would see the squadron’s standard being handed over from 8Sqn/North to 8Sqn/South. The day marked the end of a nineteen year “temporary solution” and from that day onward the fleet of seven Sentry AEW-1 aircraft have been responsible for the Royal Air Forces’ AEW commitment to NATO. It also ended an uninterrupted 39 years of British service of the World War Two vintage AN/APS 20 radar.
In 1996 No23 Squadron was reformed as part of the Waddington AEW wing and shares operation of the seven aircraft with No 8 Sqn, as a result of this dual operation the aircraft carry the markings of both squadrons. |
The Sentry