An airborne early warning and control (AEW&C) system is an airborne radarearly warning system designed to detect aircraft, ships, vehicles, missiles and other incoming projectiles at long ranges, as well as performing command and control of the battlespace in aerial engagements by informing and directing friendly fighter and attack aircraft. AEW&C units are also used to carry out aerial surveillanceover ground and maritime targets, and frequently perform battle management command and control (BMC2). When used at altitude, the radar system on AEW&C aircraft allows the operators to detect, track and prioritize targets and identify friendly aircraft from hostile ones in real-time and from much farther away than ground-based radars.[1] Like ground-based radars, AEW&C systems can be detected and targeted by opposing forces, but due to aircraft mobility and extended sensor range, they are much less vulnerable to counter-attacks than ground systems.[2]
AEW&C aircraft are used for both defensive and offensive air operations, and serve air forces in the same role as what the combat information center is to navalwarships, in addition to being a highly mobile and powerful radar platform. So useful and advantageous is it to have such aircraft operating at a high altitude, that some navies also operate AEW&C aircraft for their warships at sea, either coastal- or carrier-based and on both fixed-wing and rotary-wing platforms. In the case of the United States Navy, the Northrop Grumman E-2 Hawkeye AEW&C aircraft is assigned to its supercarriers to protect them and augment their onboard command information centers (CICs). The designation "airborne early warning" (AEW) was used for earlier similar aircraft used in the less-demanding radar picket role,[3] 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 the name of the specific system installed in the E-3 and Japanese Boeing E-767 AEW&C airframes, but is often used as a general synonym for AEW&C.[4][5]
General characteristics
Wellington Ic "Air Controlled Interception" showing rotating radar antenna
Modern AEW&C systems can detect aircraft from up to 400km (220nmi) away, well out of range of most surface-to-air missiles. One AEW&C aircraft flying at 9,000m (30,000ft) can cover an area of 312,000km2 (120,000sqmi). Three such aircraft in overlapping orbits can cover the whole of Central Europe.[6] AEW&C system indicates close and far proximity range on threats and targets, help extend the range of their sensors, and make offensive aircraft harder to track by avoiding the need for them to keep their own radar active, which the enemy can detect. Systems also communicate with friendly aircraft, vectoring fighters towards hostile aircraft or any unidentified flying object.
History of development
After having developed Chain Home—the first ground-based early-warning radar detection system—in the 1930s, the British developed a radar set that could be carried on an aircraft for what they termed "Air Controlled Interception". The intention was to cover the North West approaches where German long range Focke-Wulf Fw 200 Condor aircraft were threatening shipping. A Vickers Wellington bomber (serial R1629) was fitted with a rotating antenna array. It was tested for use against aerial targets and then for possible use against German E boats.[7][8] Another radar equipped Wellington with a different installation was used to direct Bristol Beaufighters toward Heinkel He 111s, which were air-launching V-1 flying bombs.[9][10]
In February 1944, the US Navy ordered the development of a radar system that could be carried aloft in an aircraft under Project Cadillac.[11] A prototype system was built and flown in August on a modified TBM Avengertorpedo bomber. Tests were successful, with the system being able to detect low flying formations at a range greater than 100 miles (160km). US 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 27 eventually constructed.[12] It was also recognised that a larger land-based aircraft would be attractive, thus, under the Cadillac II program, multiple Boeing B-17G Flying Fortress bombers were also outfitted with the same radar.[13]
The Lockheed WV and EC-121 Warning Star, which first flew in 1949, served widely with US Air Force and US Navy. It provided the main AEW coverage for US forces during the Vietnam war.[14] It remained operational until replaced with the E-3 AWACS.[15] Developed roughly in parallel, N-class blimps were also used as AEW aircraft, filling gaps in radar coverage for the continental US, their tremendous endurance of over 200 hours being a major asset in an AEW aircraft.[16][17] Following a crash, the US Navy opted to discontinue lighter than air operations in 1962.[18]
In 1958, the SovietTupolev Design Bureau was ordered to design an AEW aircraft.[19] After determining that the projected radar instrumentation would not fit in a Tupolev Tu-95 or a Tupolev Tu-116, the decision was made to use the more capacious Tupolev Tu-114 instead.[19] This solved the problems with cooling and operator space that existed with the narrower Tu-95 and Tu-116 fuselage.[19] To meet range requirements, production examples were fitted with an air-to-air refueling probe.[20] The resulting system, the Tupolev Tu-126, entered service in 1965 with the Soviet Air Forces and remained in service until replaced by the Beriev A-50 in 1984.[20]
During the Cold war, United Kingdom deployed a substantial AEW capability, initially 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.[21] With the retirement of 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.[22] To replace the Shackleton AEW.2, an AEW variant of the Hawker Siddeley Nimrod, known as the Nimrod AEW3, was ordered in 1974. 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.[23][22]
When AWACS first entered service it represented a major advance in capability, being the first AEW to use a pulse-Doppler radar, which allowed it to track targets normally lost in ground clutter.[26] Previously, low-flying aircraft could only be readily tracked over water.[26] The AWACS features a three-dimensional radar that measures azimuth, range, and elevation simultaneously; the unit installed upon the E-767 has superior surveillance capability over water compared to the AN/APY-1 system on the earlier E-3 models.[27][28]
The E-2 Hawkeye was a specially designed AEW aircraft. Upon its entry to service in 1965, it was initially plagued by technical issues, causing a (later reversed) cancellation.[29] Procurement resumed after efforts to improve reliability, such as replacement of the original rotary drum computer used for processing radar information by a Litton L-304 digital computer.[30][31] In addition to purchases by the US Navy, the E-2 Hawkeye has been sold to the armed forces of Egypt, France, Israel, Japan, Singapore and Taiwan.[32]
The latest E-2 version is the E-2D Advanced Hawkeye, which features the new AN/APY-9 radar.[33] The APY-9 radar has been speculated to be capable of detecting fighter-sized stealth aircraft, which are typically optimized against high frequencies like Ka, Ku, X, C and parts of the S-bands. Historically, UHF radars had resolution and detection issues that made them ineffective for accurate targeting and fire control; Northrop Grumman and Lockheed claim that the APY-9 has solved these shortcomings in the APY-9 using advanced electronic scanning and high digital computing power via space/time adaptive processing.[34]
The Russian Aerospace Forces are currently using approximately 3-5 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. The A-50 and A-50U will eventually be replaced by the Beriev A-100, which features an AESA array in the radome and is based on the updated Il-476.[35]
In May 1997, Russia and Israel agreed to jointly fulfill an order from China to develop and deliver an early warning system. China reportedly ordered one Phalcon for $250 million, which entailed retrofitting a Russian-made Ilyushin-76 cargo plane [also incorrectly reported as a Beriev A-50 Mainstay] with advanced Elta electronic, computer, radar and communications systems. Beijing was expected to acquire several Phalcon AEW systems, and reportedly could buy at least three more [and possibly up to eight] of these systems, the prototype of which was planned for testing beginning in 2000. In July 2000, the US pressured Israel to back out of the $1 billion agreement to sell China four Phalcon phased-array radar systems. Following the cancelled A-50I/Phalcon deal, China turned to indigenous solutions. The Phalcon radar and other electronic systems were taken off from the unfinished Il-76, and the airframe was handed to China via Russia in 2002. The Chinese AWACS has a unique phased array radar (PAR) carried in a round radome. Unlike the US AWACS aircraft, which rotate their rotodomes to give a 360 degree coverage, the radar antenna of the Chinese AWACS does not rotate. Instead, three PAR antenna modules are placed in a triangular configuration inside the round radome to provide a 360 degree coverage. The installation of equipment at the Il-76 began in late 2002 aircraft by Xian aircraft industries (Xian Aircraft Industry Co.). The first flight of an airplane KJ-2000 made in November 2003. All four machines will be equipped with this type. The last to be introduced into service the Chinese Air Force until the end of 2007.[citation needed] China is also developing a carrier-based AEW&C, Xian KJ-600 via Y-7 derived Xian JZY-01 testbed.
Republic of Singapore Air Force Gulfstream G550 CAEW
The EL/W-2085 is an airborne early warning and control (AEW&C) multi-band radar system developed by Israel Aerospace Industries (IAI) and its subsidiary Elta Systems of Israel. Its primary objective is to provide intelligence to maintain air superiority and conduct surveillance. The system is currently in service with Israel, Italy, and Singapore. Instead of using a rotodome, a moving radar was found on some AEW&C aircraft, and the EL/W-2085 used an active electronically scanned array (AESA) – an active phased array radar. This radar consists of an array of transmit/receive (T/R) modules that allow a beam to be electronically steered, making a physically rotating rotodome unnecessary.
AESA radars operate on a pseudorandom set of frequencies and also have very short scanning rates, which makes them difficult to detect and jam. Up to 1000 targets can be tracked simultaneously to a range of 243 mi (450 km), while at the same time, multitudes of air-to-air interceptions or air-to-surface (including maritime) attacks can be guided simultaneously. The radar equipment of the Israeli AEW&C consists of each L-band radar on the left and right sides of the fuselage and each S-band antenna in the nose and tail. The phased array allows aircraft positions on operator screens to be updated every 2–4 seconds rather than every 10 seconds, as is the case on the rotodome AWACS.[36]
ELTA was the first company to introduce an Active Electronically Scanned Array Airborne (AESA) Early Warning Aircraft and implement advanced mission aircraft using efficient, high-performance business jet platforms.
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 (AWAC) system.[37] In 2015, DRDO delivered 3 AWACs, called Netra, to the IAF with an advanced Indian AESA radar system fitted on the Brazilian Embraer EMB-145 air frame.[38] Netra gives a 240-degree coverage of airspace. The Emb-145 also has air-to-air refuelling capability for longer surveillance time. The IAF also operates three Israeli EL/W-2090 systems, mounted on Ilyushin Il-76 airframes, the first of which first arrived on 25 May 2009.[39][40] The DRDO proposed a more advanced AWACS with a longer range and with a 360-degree coverage akin to the Phalcon system, based on the Airbus A330 airframe,[38][41] but given the costs involved there is also the possibility of converting used A320 airliners as well.[42]
IAF has plans to develop 6 more Netra AEW&CS based on Embraer EMB-145 platform[43] and another 6 based on Airbus A321 platform.[44][45] These systems are expected to have an enhanced performance including range and azimuth
The Royal Australian Air Force, Republic of Korea Air Force and the Turkish Air Force are deploying Boeing 737 AEW&C aircraft. The Boeing 737 AEW&C has a fixed, active electronically scanned array radar antenna instead of a mechanically-rotating one, and is capable of simultaneous air and sea search, fighter control and area search, with a maximum range of over 600km (look-up mode). In addition, the radar antenna array is also doubled as an ELINT array, with a maximum range of over 850km at 9,000 metres (30,000ft) altitude.[46]
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 to enter service. The original Phalcon was mounted on a Boeing 707[53] and developed for the Israeli Defense Force and for export. Israel uses IAI EL/W-2085 airborne early warning and control multi-band radar system on Gulfstream G550; this platform is considered to be both more capable and less expensive to operate than the older Boeing 707-based Phalcon fleet.[54]
In 2017, India announced plans to purchase six airborne early warning and control (AEW&C) ("AWACS") aircraft that can also perform aerial refuelling,[55] with the first two AEW&C aircraft awaiting approval by Cabinet in 2020.[56] However, in September 2021, it was decided to use six Airbus A321s acquired from Air India instead.[57][58]
On 3 June 1957, the first of 2 HR2S-1W, a derivative of the Sikorsky CH-37 Mojave, was delivered to the US Navy, it used the AN/APS-32 but proved unreliable due to vibration.[59]
The British Sea King ASaC7 naval helicopter was operated from both the Invincible-classaircraft carriers and later the helicopter carrier HMSOcean. The creation of Sea King ASaC7, and earlier AEW.2 and AEW.5 models, came as the consequence of lessons learnt by the Royal Navy during the 1982 Falklands War when the lack of AEW coverage for the task force was a major tactical handicap, and rendered them vulnerable to low-level attack.[60] The Sea King was determined to be both more practical and responsive than the proposed alternative of relying on the RAF's land-based Shackleton AEW.2 fleet. The first examples were a pair of Sea King HAS2s that had the Thorn-EMI ARI 5980/3 Searchwater LAST radar attached to the fuselage on a swivel arm and protected by an inflatable dome.[60] The improved Sea King ASaC7 featured the Searchwater 2000AEW radar, which was capable of simultaneously tracking up to 400 targets, instead of an earlier limit of 250 targets.[61][62] The Spanish Navy fields the SH-3 Sea King in the same role, operated from the LPH Juan Carlos I. [citation needed]
The AgustaWestland EH-101A AEW of the Italian Navy is operated from the aircraft carriers Cavour and Giuseppe Garibaldi.[63] During the 2010s, the Royal Navy opted to replace its Sea Kings with a modular "Crowsnest" system that can be fitted to any of their Merlin HM2 fleet.[64][65] The Crowsnest system was partially based upon the Sea King ASaC7's equipment; an unsuccessful bid by Lockheed Martin had proposed using a new multi-functional sensor for either the AW101 or another aircraft.[66][67]
The Russian-built Kamov Ka-31 is deployed by the Indian Navy on the aircraft carriers INSVikramaditya and INSVikrant and also on Talwar-class frigates.[68] The Russian Navy has two Ka-31R variants, at least one of which was deployed on their aircraft carrier Admiral Kuznetsov in 2016.[69] It is fitted with E-801M Oko (Eye) airborne electronic warfare radar that can track 20 targets simultaneously, detecting aircraft up to 150km (90mi) away, and surface warships up to 200km (120mi) distant.
The Boeing E-3 Sentry is an American airborne early warning and control (AEW&C) aircraft developed by Boeing. E-3s are commonly known as AWACS. Derived from the Boeing 707 airliner, it provides all-weather surveillance, command, control, and communications, and is used by the United States Air Force, NATO, French Air and Space Force, Royal Saudi Air Force and Chilean Air Force. The E-3 has a distinctive rotating radar dome (rotodome) above the fuselage. Production ended in 1992 after 68 aircraft had been built.
The Northrop Grumman E-2 Hawkeye is an American all-weather, carrier-capable tactical airborne early warning (AEW) aircraft. This twin-turboprop aircraft was designed and developed during the late 1950s and early 1960s by the Grumman Aircraft Company for the United States Navy as a replacement for the earlier, piston-engined E-1 Tracer, which was rapidly becoming obsolete. The aircraft's performance has been upgraded with the E-2B and E-2C versions, where most of the changes were made to the radar and radio communications due to advances in electronic integrated circuits and other electronics. The fourth major version of the Hawkeye is the E-2D, which first flew in 2007. The E-2 was the first aircraft designed specifically for AEW, as opposed to a modification of an existing airframe, such as the Boeing E-3 Sentry. Variants of the Hawkeye have been in continuous production since 1960, giving it the longest production run of any carrier-based aircraft.
The Boeing E-7 Wedgetail, also marketed as the Boeing 737 AEW&C, is a twin-engine airborne early warning and control aircraft based on the Boeing 737 Next Generation design. It has a fixed, active electronically scanned array radar antenna instead of a rotating one as with the 707-based Boeing E-3 Sentry. The E-7 was designed for the Royal Australian Air Force (RAAF) under "Project Wedgetail" and designated E-7A Wedgetail.
The Beriev A-50 is a Soviet-origin airborne early warning and control (AEW&C) aircraft that is based on the Ilyushin Il-76 transport plane. Developed to replace the Tupolev Tu-126 "Moss", the A-50 first flew in 1978. Its existence was revealed to the Western Bloc in 1978 by Adolf Tolkachev. It entered service in 1985, with about 40 produced by 1992.
The EL/M-2075 Phalcon is an airborne early warning and control (AEW&C) active electronically scanned array radar system developed by Israel Aerospace Industries (IAI) and Elta Electronics Industries of Israel. Its primary objective is to provide intelligence to maintain air superiority and conduct surveillance. It was surpassed by newer versions—the EL/W-2085 and the EL/W-2090.
The KJ-1 was a Chinese experimental airborne early warning (AEW) aircraft, based on a Tupolev Tu-4 bomber aircraft. The project was started in 1969 under the code name "Project 926", but only one prototype was built before the project was put on hold indefinitely until it was finally cancelled in 1979.
The KJ-2000 is a Chinese second-generation airborne early warning and control (AEW&C) aircraft developed by the Shaanxi Aircraft Corporation, and is the first AEW&C system in service to the People's Liberation Army Air Force. It is built upon a modified Russian Ilyushin Il-76 airframe using domestically designed avionics and a fixed radome featuring three active electronically scanned array (AESA) radars each covering a 120-degree sector, unlike the rotating radome on the comparable E-3 Sentry serving the United States Air Force.
The Kamov Ka-31 is a military helicopter originally developed for the Soviet Navy and currently in service in Russia, China, and India in the naval airborne early warning and control role.
The Boeing E-767 is an Airborne Warning and Control System (AWACS) aircraft that was designed in response to the Japan Air Self-Defense Force's requirements. It is essentially the Boeing E-3 Sentry's surveillance radar and air control system installed on a Boeing 767-200.
The 111 Squadron "Jaeger" was formed when the Republic of Singapore Air Force acquired four Grumman E-2C Hawkeye Airborne Early Warning aircraft in 1987. Based at Tengah Air Base, its primary function is to perform airborne surveillance and early warning. Other functions include Aircraft Intercept Control, Surface Surveillance, Search and Rescue and Air Traffic Control.
The Airborne Surveillance Platform (ASP) is an Indian defence project initiated by the Defence Research and Development Organisation (DRDO) with the aim to produce an Airborne Early Warning System. Two prototypes were developed and flight tested for three years. The project was cancelled in 1999 after the prototype aircraft crashed, killing eight scientists and the aircrew. After four years of inactivity, the project was revived in 2004 with a new platform and radar.
The DRDO Airborne Early Warning and Control System (AEW&CS) is a project of India's Defence Research and Development Organisation to develop an airborne early warning and control system for the Indian Air Force. It is also referred to as NETRA Airborne Early Warning and Control System (AEW&CS).
The Saab 340 AEW&C is a Swedish airborne early warning and control (AEW&C) aircraft. A variant of the Saab 340 aircraft is designated S 100B Argus by the Swedish Air Force.
The EL/W-2085 is an airborne early warning and control (AEW&C) multi-band radar system developed by Israel Aerospace Industries (IAI) and Elta Electronics Industries of Israel. Its primary objective is to provide intelligence to maintain air superiority and conduct surveillance. The system is currently in-service with Israel, Italy, and Singapore.
The British Aerospace Nimrod AEW3 was a proposed airborne early warning (AEW) aircraft which was to provide airborne radar cover for the air defence of the United Kingdom by the Royal Air Force (RAF). The project was designed to use the existing Nimrod airframe, in use with the RAF as a maritime patrol aircraft, combined with a new radar system and avionics package developed by Marconi Avionics.
The IAI EL/W-2090 is an airborne early warning and control (AEW&C) radar system developed by Israel Aerospace Industries (IAI) and Elta Electronics Industries of Israel. Its primary objective is to provide intelligence to maintain air superiority and conduct surveillance. The system is currently in-service with the Indian Air Force.
The Fairey Gannet AEW.3 is a variant of the Fairey Gannet anti-submarine warfare aircraft intended to be used in the airborne early warning (AEW) role on aircraft carriers of the Royal Navy. It was introduced to service in 1959 to replace the obsolete Douglas Skyraider, and was intended as an interim solution until the planned introduction of a new, purpose built AEW platform for use on the planned CVA-01 aircraft carriers. Neither the new aircraft carriers nor the new AEW aircraft were proceeded with, and the Gannet AEW.3 remained in service until the last aircraft carrier that could operate it was retired in 1978.
The Hawker Siddeley P.139B was a proposed airborne early warning aircraft intended to operate from aircraft carriers of the Royal Navy. The P.139B formed part of the a major equipment procurement plan for the RN in the 1960s intended to give the service a force of new, modern carriers capable of operating air groups consisting of equally modern aircraft. However, cuts in defence spending by the British government in the mid-1960s meant that these proposals never came to fruition.
↑ R.H. Hamilton in Perkins, L.W., ed., Flight into Yesterday – A Memory or Two from Members of the Wartime Aircrew Club of Kelowna, L.P. Laserprint, Ltd., Kelowna, B.C., 2000, and 407 Squadron History 1941–1996 – a Narrative History, 407 Squadron, 1996.
↑ "The Litton L-304 Dual Computer System". trailing-edge.com. 1966. p.2. Retrieved 1 August 2016. L-304E with 4096 words of memory was completed and put in operation. Very shortly thereafter, the computer was tied to a typewriter, paper tape reader and punch, a small magnetic tape, a real-time clock and a small CRT display and control console.Alt URL
↑ Donald, David, ed. "Grumman E-2 Hawkeye/TE-2/C-2 Greyhound". The Complete Encyclopedia of World Aircraft. Barnes & Nobel Books, 1997. ISBN0-7607-0592-5.
Armistead, Leigh and Edwin Armistead. Awacs and Hawkeyes: The Complete History of Airborne Early Warning Aircraft. St Paul, Minnesota: Zenith Imprint, 2002. ISBN0-7603-1140-4.
Davies, Ed. "AWACS Origins: Brassboard – Quest for the E-3 Radar". Air Enthusiast. No.119, September/October 2005. Stamford, Lincs, UK: Key Publishing. pp.2–6. ISSN0143-5450.
Gibson, Chris (2011). The Admiralty and AEW: Royal Navy Airborne Early Warning Projects. Blue Envoy Press. ISBN978-0956195128.
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