Airborne early warning and control
An airborne early warning and control (AEW&C) system is an airborne radar picket system designed to detect aircraft, ships and vehicles at long ranges and perform control and command of the battle space in an air engagement by directing fighter and attack aircraft strikes. AEW&C units are also used to carry out surveillance, including over ground targets and frequently perform C2BM (command and control, battle management) functions similar to an Airport Traffic Controller given military command over other forces. When used at altitude, the radar on the aircraft allows the operators to detect and track targets and distinguish between friendly and hostile aircraft much farther away than a similar ground based radar. Like a ground based radar, it can be detected by opposing forces, but because of its mobility, it is much less vulnerable to counter-attack.
AEW&C aircraft are used for both defensive and offensive air operations, and are to the NATO and US forces trained or integrated Air Forces what the Command Information Center is to a US Navy warship, plus a highly mobile and powerful radar platform. The system is used offensively to direct fighters to their target locations, and defensively, directing counterattacks on enemy forces, both air and ground. So useful is the advantage of command and control from a high altitude, the United States Navy operates Northrop Grumman E-2 Hawkeye AEW&C aircraft off its Supercarriers to augment and protect its carrier Command Information Centers (CICs). The designation "airborne early warning" (AEW) was used for earlier similar aircraft, such as the Fairey Gannet AEW.3 and Lockheed EC-121 Warning Star, and continues to be used by the RAF for its Sentry AEW1, while AEW&C (airborne early warning and control) emphasizes the command and control capabilities that may not be present on smaller or simpler radar picket aircraft. AWACS (Airborne Warning And Control System) is name of the specific system installed in the E-3 and Japanese E-767 AEW&C airframes.
Modern AEW&C systems can detect aircraft from up to 250 miles (400 km) away, well out of range of most surface-to-air missiles. One AEW&C aircraft flying at 30,000 feet (9,100 m) can cover an area of 120,460 square miles (312,000 km2). Three such aircraft in overlapping orbits can cover the whole of Central Europe. In air-to-air combat, AEW&C systems can communicate with friendly aircraft, extend their sensor range and make them more difficult to track, since they no longer need their own active radar to detect threats.
History of development
As part of their early use of radar, the British developed a radar set that could be carried on an aircraft for "Air Controlled Interception". The intention was to cover the North West approaches where German long range Fw 200 Condor aircraft were a threat to shipping. A Vickers Wellington bomber (serial R1629) was fitted with a rotating antenna array. It was trialled for use against aerial targets and then for possible use against German E boats. Another installation was a radar equipped Wellington used to direct Bristol Beaufighters onto Heinkel He 111s, which were air-launching V-1 flying bombs.
In February 1944 the U.S. Navy ordered the development of a radar system that could be carried aloft in an aircraft as Project Cadillac. A prototype system was built and flown in August on a modified TBM Avenger torpedo bomber. Tests proved successful, with the system being able to detect low flying formations at a range in excess of 100 miles (160 km). The U.S. Navy then ordered production of the TBM-3W, the first production AEW aircraft to enter service. TBM-3Ws fitted with the AN/APS-20 radar entered service in March 1945, with some 36–40 eventually being constructed.
In 1958, the Soviet Tupolev Design Bureau was also ordered to design an AEW aircraft. After determining that the projected radar instrumentation wouldn't fit in a Tu-95 or a Tupolev Tu-116, the decision was made to use the more capacious Tu-114 instead. This solved the problems with cooling and operator space that existed with the narrower Tu-95 and Tu-116 fuselage. To meet the flight range requirements, production examples were fitted with an air-to-air refueling probe. The resulting plane, the Tu-126, entered service in 1965 with the Soviet Air Forces and remained in service until replaced by the Beriev A-50 in 1984.
Many countries have developed their own AEW&C systems, although the Boeing E-3 Sentry and Northrop Grumman E-2 Hawkeye are the most common systems worldwide. The E-3 Sentry was built by the Boeing Defense and Space Group (now Boeing Defense, Space & Security) and was based on the Boeing 707-320 aircraft. 65 E-3 were built and it is operated by the United States Air Force, NATO, the British Royal Air Force, France and controversially, Saudi Arabia.
The specially designed Grumman E-2 Hawkeye entered service in 1965 and has been operated by eight different nations. Over 168 have been produced so far and new versions continue to be developed making it the most widely used AEW system. For the Japan Air Self-Defense Force, the E-3 technology has been fitted into the Boeing E-767.
After World War 2, the United Kingdom deployed a substantial AEW capability with American Douglas AD-4W Skyraiders, designated Skyraider AEW.1, which in turn were replaced by the Fairey Gannet AEW.3, using the same AN/APS-20 radar. With the retirement of the conventional aircraft carriers, the Gannet was withdrawn and the Royal Air Force (RAF) installed the radars from the Gannets on Avro Shackleton MR.2 airframes, redesignated Shackleton AEW.2. To replace the Shackleton AEW.2, an AEW variant of the Hawker Siddeley Nimrod, known as the Nimrod AEW3, was ordered in 1974. However, after a protracted and problematic development, this was cancelled in 1986, and seven E-3Ds, designated Sentry AEW.1 in RAF service, were purchased instead.
The Russian Air Force is currently using around 15–20 Beriev A-50 and A-50U "Shmel" in the AEW role. The "Mainstay" is based on the Ilyushin Il-76 airframe, with a large non-rotating disk radome on the rear fuselage. These replaced the 12 Tupolev Tu-126 that filled the role previously.
In 2003, the Indian Air Force (IAF) and Defence Research and Development Organisation (DRDO) began a study of requirements for developing an Airborne Early Warning and Control (AEWAC) system. The Indian Air Force operates three EL/W-2090 systems, the first of which first arrived on May 25, 2009. The air force is also testing the DRDO AEW&CS.
The Royal Australian Air Force, Republic of Korea Air Force and the Turkish Air Force are deploying Boeing 737 AEW&C aircraft. Unlike the E-2 and E-3, the Boeing 737 AEW&C does not use a rotating disk radome (rotodome) but instead has a large dorsal fin.
In early 2006, the Pakistan Air Force ordered six Erieye AEW equipped Saab 2000 from Sweden for roughly $1bn. In December 2006, the Pakistan Navy requested three excess P-3 Orion aircraft to be equipped with Hawkeye 2000 AEW systems, the overall cost of the program is $855mn. China and Pakistan also signed a memorandum of understanding (MoU) for the joint development of AEW&C systems. A $278m deal has been struck with China.
Israel has developed the IAI/Elta EL/M-2075 Phalcon system, which uses an AESA (Active Electronically Scanned Array) in lieu of a rotodome antenna. The system was the first such system into service. The original Phalcon was mounted on a Boeing 707  and developed for the Israeli Defense Force and for export.
Helicopter AEW systems
The Royal Navy Sea King ASaC7 naval helicopter was operated from Invincible-class aircraft carriers. The creation of Sea King ASaC7, and earlier AEW.2 and AEW.5 is the consequence of lessons learnt by the Royal Navy in the 1982 Falklands War when the lack of AEW coverage for the task force was a major tactical shortcoming. The Spanish Navy fields the SH-3 Sea King in the same role, operated from the LPH Juan Carlos I.
The Russian-built Kamov Ka-31 is deployed by the Indian Navy on the aircraft carrier INS Vikramaditya and Talwar-class frigates and will be deployed on the Vikrant-class aircraft carriers. It is reportedly used by the Russian Navy on its sole Kuznetsov aircraft carrier. It is fitted with E-801M Oko (Eye) airborne electronic warfare radar that can track up to 20 targets simultaneously with aerial detection range 90 mi (150 km) and surface warships up to 160 mi (250 km).
Airborne Warning and Control System (AWACS)
Boeing produces a specific system with a rotating radar dome "rotodome" radome designed and built by Boeing (Defense & Space Group) using Westinghouse (now Northrop Grumman) radar. It is mounted on either the E-3 Sentry aircraft (Boeing 707) or more recently a modified Boeing 767. Only the Japanese Air Self-Defense Force has the 767 version, calling it the E-767. When it first entered service it represented a major step forward, being the first AEW to use a pulse-doppler radar, which allowed it to track low flying targets normally lost in ground clutter. Previously low-flying aircraft could only be readily tracked over water.
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|Wikimedia Commons has media related to Early Warning Aircraft (AEW/AWACS).|
- AWACS and JSTARS
- NATO AWACS-Spotter Geilenkirchen website
- FAS.org E-3 Sentry information
- Boeing AWACS website
- Airborne Early Warning Association website
- TU-126 MOSS AWACS – history of development- in Russian
- Airborne radar "Gneis-2" – in Russian