Airborne early warning and control

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File:Royal Air Force (RAF) E-3D Sentry AEW1 (airborne early warning) aircraft, registration ZH106, taking part in Exercise Taurus Mountain 3, in the skies over North Yorkshire in March 2012 - MOD 45153803 (cropped).jpg

A Royal Air Force Boeing E-3 Sentry over North Yorkshire

An airborne early warning and control (AEW&C) system is an airborne radar early 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 surveillance over 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.<ref>Neufeld 1997, p. 276.</ref> 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.<ref>Neufeld 1997, p. 278.</ref>

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 naval warships, 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,<ref>Gordon 2010, p. 3.</ref> 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 American Boeing E-3 Sentry and Japanese Boeing E-767 AEW&C airframes, but is often used as a general synonym for AEW&C.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=gap />

General characteristicsEdit

File:Wellington Ic (R1629).jpg

Wellington Ic "Air Controlled Interception" showing rotating radar antenna

Modern AEW&C systems can detect aircraft from up to Template:Convert away, well out of range of most surface-to-air missiles. One AEW&C aircraft flying at Template:Convert can cover an area of Template:Convert. Three such aircraft in overlapping orbits can cover the whole of Central Europe.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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 developmentEdit

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.<ref>Air-Britain, Aviation World, 2004,</ref><ref>Hodges, R, "Air controlled interception," Radar Development to 1945 R W Burns (ed),</ref> 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.<ref>Flypastm April 1987: "The First AWACS".</ref><ref>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.</ref>

In February 1944, the US Navy ordered the development of a radar system that could be carried aloft in an aircraft under Project Cadillac.<ref>Hirst 1983, p. 59.</ref> A prototype system was built and flown in August on a modified TBM Avenger torpedo bomber. Tests were successful, with the system being able to detect low flying formations at a range greater than Template:Convert. 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.<ref>Hirst 1983, p. 64.</ref> 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.<ref>Hirst 1983, p. 60.</ref>

File:Lockheed EC-121M with F-4B (cropped).jpg

Lockheed EC-121M one of the first AEW aircraft

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.<ref name="jtc">Corell, John T. "Igloo White." Air Force Magazine, Vol. 87, No. 11, November 2004 via web.archive.org. Retrieved: 23 December 2010.</ref> It remained operational until replaced with the E-3 AWACS.<ref>Wilson 1998, p. 72.</ref> 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.<ref>"Navy Airship Longer Than Football Field." Popular Mechanics, September 1952, p. 117, bottom.</ref><ref name=SkyShips>Sky Ships: A History of the Airship in the United States Navy, Althoff, W.F., Pacifica Press, c1991, Template:ISBN</ref> Following a crash, the US Navy opted to discontinue lighter than air operations in 1962.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In 1958, the Soviet Tupolev Design Bureau was ordered to design an AEW aircraft.<ref name=Tu-114.1>Gordon 2006, p. 86.</ref> 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.<ref name=Tu-114.1 /> This solved the problems with cooling and operator space that existed with the narrower Tu-95 and Tu-116 fuselage.<ref name=Tu-114.1 /> To meet range requirements, production examples were fitted with an air-to-air refueling probe.<ref name=Tu-114.2>Gordon 2006, p. 87.</ref> 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.<ref name=Tu-114.2 />

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.<ref name="Gibson10">Template:Harvnb</ref> 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.<ref name ="Tyack 87"/> 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.<ref name="spyflight">"BAe Nimrod AEW 3." Template:Webarchive Spyflight. Retrieved: 21 October 2010.</ref><ref name ="Tyack 87">Tyack 2005, p. 87.</ref>

The US Defense Department is considering options to move the air moving target indicator (AMTI) mission component from AWACS aircraft to space-based platforms. The space-based sensor is already in orbit and in testing phase.<ref> https://aviationweek.com/defense/sensors-electronic-warfare/norad-commander-amti-prototype-sensors-are-orbit-now</ref>

Current systemsEdit

Many countries have developed their own AEW&C systems, although the Boeing E-3 Sentry, E-7A<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and Northrop Grumman E-2 Hawkeye and Gulfstream/IAI EL/W-2085 are the most common systems worldwide.

Airborne Warning and Control System (AWACS)Edit

File:Boeing E-767 (light).jpg

E-767 of the Japan Air Self Defense Force

Template:See also Boeing produces a specific system with a "rotodome" rotating radome that incorporates Westinghouse (now Northrop Grumman) radar.<ref name="gap">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It is mounted on either the E-3 Sentry aircraft (Boeing 707) or more recently the Boeing E-767 (Boeing 767), the latter only being used by the Japan Air Self-Defense Force.<ref name=aw30>Air World, April 1998 Special edition "Airborne Early Warning and Control aircraft E-767 & E-3" p. 30.</ref>

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.<ref name=USAF>Neufeld 1997, p. 271.</ref> Previously, low-flying aircraft could only be readily tracked over water.<ref name=USAF /> The AWACS features a three-dimensional radar that measures azimuth, range, and elevation simultaneously; the AN/APY-2 unit installed upon the E-767 and later E-3 models has superior surveillance capability over water compared to the AN/APY-1 system on the earlier E-3 models.<ref name=aw37>Air World, April 1998 Special edition "Airborne Early Warning and Control aircraft E-767 & E-3" p. 37.</ref><ref name=boeing_e-767-overview>Boeing 767 AWACS Overview Template:Webarchive. Boeing</ref>

E-2 HawkeyeEdit

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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.<ref name="JAWA76 p291">Taylor 1976, p. 291.</ref> 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.<ref>Template:Cite journal

Template:Cite journal</ref><ref>{{#invoke:citation/CS1|citation

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Template:Cite journal</ref> 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.<ref name="World Aircraft">Donald, David, ed. "Grumman E-2 Hawkeye/TE-2/C-2 Greyhound". The Complete Encyclopedia of World Aircraft. Barnes & Nobel Books, 1997. Template:ISBN.</ref>

The latest E-2 version is the E-2D Advanced Hawkeye, which features the new Template:AnchorAN/APY-9 radar.<ref>Template:Cite news</ref> 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.<ref>The U.S. Navy's Secret Counter-Stealth Weapon Could Be Hiding in Plain Sight Template:Webarchive – News.USNI.org, 9 June 2014.</ref>

Beriev A-50Edit

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File:Самолет ДРЛО А-50У (1).png

Beriev A-50

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.<ref>Butowski, Piotr. "Model Reveals A-100 Configuration". Air International, April 2014. Retrieved: 21 July 2014.</ref>

KJ-2000Edit

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File:KJ2000 at 2014 Zhuhai Air Show.jpg

KJ-2000 at 2014 Zhuhai Air Show

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.Template:Citation needed China is also developing a carrier-based AEW&C, Xian KJ-600 via Y-7 derived Xian JZY-01 testbed.

EL/W-2085 AEW&CEdit

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File:RSAF Gulfstream IAI G550 CAEW (cropped).jpg

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.<ref>{{#invoke:URL|url}}{{#invoke:Check for unknown parameters|check|unknown=Template:Main other|preview=Page using Template:URL with unknown parameter "_VALUE_"|ignoreblank=y | 1 | 2 }}</ref>

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.

Netra AEW&CSEdit

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File:DRDO AEW&C Embraer ERJ 145.JPG

Netra AEW&C in Aero India 2017

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.<ref>Template:Cite press release</ref> 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.<ref name=":0">Template:Cite news</ref> 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.<ref>Template:Cite news</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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,<ref name=":0" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> but given the costs involved there is also the possibility of converting used A320 airliners as well.<ref name="a320conv1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

IAF has plans to develop 6 more Netra AEW&CS based on Embraer EMB-145 platform<ref>Template:Cite news</ref> and another 6 based on Airbus A321 platform.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> These systems are expected to have an enhanced performance including range and azimuth

Boeing 737 AEW&CEdit

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File:Boeing 737 AEW&C MESA Peace Eagle.jpg

A Turkish Air Force Boeing 737 AEW&C

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 600 km (look-up mode). In addition, the radar antenna array is also doubled as an ELINT array, with a maximum range of over 850 km at Template:Convert altitude.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Erieye/GlobalEyeEdit

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File:Aeronaves Ágata 7 - FAB - EMB145 Erieye.jpg

A Brazilian Air Force Embraer R-99

The Swedish Air Force uses the S 100D Argus ASC890 as its AEW platform. The S 100D Argus is based on the Saab 340 with an Ericsson Erieye PS-890 radar. Saab also offers the Bombardier Global 6000-based GlobalEye. In early 2006, the Pakistan Air Force ordered six Erieye AEW equipped Saab 2000s from Sweden.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In December 2006, the Pakistan Navy requested three excess P-3 Orion aircraft to be equipped with Hawkeye 2000 AEW systems.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> China and Pakistan also signed a memorandum of understanding (MoU) for the joint development of AEW&C systems.<ref>Template:Cite news</ref>

The Hellenic Air Force, Brazilian Air Force and Mexican Air Force use the Embraer R-99 with an Ericsson Erieye PS-890 radar, as on the S 100D.<ref>Hellenic Air Force: Embraer EMB-145H AEW&C Template:Webarchive</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

OthersEdit

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<ref name="B707 Phalcon, Israeli Weapons.com">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>Template:Cite news</ref> North Korea appears to operate an AEW&C plane based on the Il-76.<ref name=Trevithick /> North korean designation and design details are unclear.<ref name=Trevithick>Template:Cite news</ref>

Helicopter AEW systemsEdit

File:Royal Navy AEW Seaking Helicopter from 849 Naval Air Squadron MOD (cropped).jpg

An AEW Westland Sea King helicopter of the Royal Navy

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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The British Sea King ASaC7 naval helicopter was operated from both the Template:Sclasss and later the helicopter carrier Template:HMS. 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.<ref name = 'Armistead 131'>Armistead and Armistead 2002, p. 131.</ref> 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.<ref name = 'Armistead 131'/> 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.<ref>"Cerberus set for service aboard Sea King Whiskey, Upgrade Update." Template:Webarchive Jane's International Defence Review, 24 September 2002. Retrieved 19 April 2012.</ref><ref name ='Armistead 132-134'>Armistead and Armistead 2002, pp. 132–134.</ref> The Spanish Navy fields the SH-3 Sea King in the same role, operated from the LPH Template:Ship. Template:Citation needed

The AgustaWestland EH-101A AEW of the Italian Navy is operated from the aircraft carriers Template:Ship and Template:Ship.<ref name="difesa">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The Russian-built Kamov Ka-31 is deployed by the Indian Navy on the aircraft carriers Template:INS and Template:INS and also on Template:Sclasss.<ref>Template:Cite news</ref> The Russian Navy has two Ka-31R variants, at least one of which was deployed on their aircraft carrier Template:Ship in 2016.<ref>Template:Citation</ref> It is fitted with E-801M Oko (Eye) airborne electronic warfare radar that can track 20 targets simultaneously, detecting aircraft up to Template:Convert away, and surface warships up to Template:Convert distant.