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The Boeing E-3 Sentry is an American
airborne early warning and control Airborne or Airborn may refer to: Arts, entertainment, and media Films * ''Airborne'' (1962 film), a 1962 American film directed by James Landis * ''Airborne'' (1993 film), a comedy–drama film * ''Airborne'' (1998 film), an action film sta ...
(AEW&C) aircraft developed by
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and ...
. E-3s are commonly known as AWACS (Airborne Warning and Control System). Derived from the
Boeing 707 The Boeing 707 is an American, long-range, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes. Developed from the Boeing 367-80 prototype first flown in 1954, the initial first flew on December ...
airliner, it provides all-weather surveillance, command, control, and communications, and is used by the
United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army S ...
,
NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...
,
French Air and Space Force The French Air and Space Force (AAE) (french: Armée de l'air et de l'espace, ) is the air and space force of the French Armed Forces. It was the first military aviation force in history, formed in 1909 as the , a service arm of the French Arm ...
,
Royal Saudi Air Force The Royal Saudi Air Force ( ar, ‎الْقُوَّاتُ الْجَوِّيَّةُ الْمَلَكِيَّةْ ٱلسُّعُوْدِيَّة, Al-Quwwat Al-Jawiyah Al-Malakiyah as-Su’udiyah) (RSAF) is the Military aviation, aviation branch o ...
and
Chilean Air Force "With full speed to the stars" , colours = Indigo White , colours_label = , march = Alte Kameraden , mascot = , anniversaries = 21 March ...
. The E-3 is distinguished by the distinctive rotating radar dome (rotodome) above the fuselage. Production ended in 1992 after 68 aircraft had been built. In the mid-1960s, the U.S. Air Force (USAF) was seeking an aircraft to replace its piston-engined
Lockheed EC-121 Warning Star The Lockheed EC-121 Warning Star was an American airborne early warning and control radar surveillance aircraft operational in the 1950s in both the United States Navy (USN) and United States Air Force (USAF). The military version of the Lock ...
, which had been in service for over a decade. After issuing preliminary development contracts to three companies, the USAF picked Boeing to construct two airframes to test Westinghouse Electric and Hughes's competing radars. Both radars used pulse-Doppler technology, with Westinghouse's design emerging as the contract winner. Testing on the first production E-3 began in October 1975. The first USAF E-3 was delivered in March 1977, and during the next seven years, a total of 34 aircraft were manufactured. E-3s were also purchased by NATO (18), the United Kingdom (7), France (4) and
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the List of Asian countries by area, fifth-largest country in Asia ...
(5). In 1991, when the last aircraft had been delivered, E-3s participated in the
Persian Gulf War The Gulf War was a 1990–1991 armed campaign waged by a Coalition of the Gulf War, 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Ba'athist Iraq, ...
, playing a crucial role of directing coalition aircraft against Iraqi forces. The aircraft's capabilities have been maintained and enhanced through numerous upgrades. In 1996, Westinghouse Electric's Defense & Electronic Systems division was acquired by Northrop Corporation, before being renamed Northrop Grumman Mission Systems, which currently supports the E-3's radar. In April 2022, the U.S. Air Force announced that the Boeing 737 AEW&C will be replacing the E-3 beginning in 2027.


Development


Background

In 1963, the USAF asked for proposals for an Airborne Warning and Control System (AWACS) to replace its EC-121 Warning Stars, which had served in the
airborne early warning Airborne or Airborn may refer to: Arts, entertainment, and media Films * ''Airborne'' (1962 film), a 1962 American film directed by James Landis * ''Airborne'' (1993 film), a comedy–drama film * ''Airborne'' (1998 film), an action film sta ...
role for over a decade. The new aircraft would take advantage of improvements in radar technology and computer-aided radar data analysis and data reduction. These developments allowed airborne radars to "
look down To look is to use sight to perceive an object. Look or The Look may refer to: Businesses and products * Look (modeling agency), an Israeli modeling agency * ''Look'' (American magazine), a defunct general-interest magazine * ''Look'' (UK m ...
", i.e. to detect the movement of low-flying aircraft, and discriminate, even over land, target aircraft's movements; previously this had been impossible due to the inability to discriminate an aircraft's track from
ground clutter Clutter is a term used for unwanted echoes in electronic systems, particularly in reference to radars. Such echoes are typically returned from ground, sea, rain, animals/insects, chaff and atmospheric turbulences, and can cause serious performan ...
.Eden et al. 2004, p. 92. Contracts were issued to Boeing, Douglas, and Lockheed, the latter being eliminated in July 1966. In 1967, a parallel program was put into place to develop the radar, with Westinghouse Electric Corporation and Hughes Aircraft being asked to compete in producing the radar system. In 1968, it was referred to as Overland Radar Technology (ORT) during development tests on the modified EC-121Q.Davies 2005, p. 2. The Westinghouse radar antenna was going to be used by whichever company won the radar competition since Westinghouse had pioneered the design of high-power
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the uppe ...
(RF) phase-shifters, which are used to both focus the RF into a pencil beam and scan electronically for altitude determination. Boeing initially proposed a purpose-built aircraft, but tests indicated it would not outperform the already-operational 707, so the latter was chosen instead. To increase endurance, this design was to be powered by eight
General Electric TF34 The General Electric TF34 is an American military turbofan engine used on the A-10 Thunderbolt II and S-3 Viking. Design and development Developed by GE Aircraft Engines during the late 1960s, the original engine comprises a single stage fan ...
s. It would carry its radar in a rotating dome mounted at the top of a forward-swept tail, above the fuselage. Boeing was selected ahead of
McDonnell Douglas McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it ...
's DC-8-based proposal in July 1970. Initial orders were placed for two aircraft, designated EC-137D, as test beds to evaluate the two competing radars. As the test beds did not need the same 14-hour endurance demanded of the production aircraft, the EC-137s retained the
Pratt & Whitney JT3D The Pratt & Whitney JT3D is an early turbofan aircraft engine derived from the Pratt & Whitney JT3C. It was first run in 1958 and was first flown in 1959 under a B-45 Tornado test aircraft. Over 8,000 JT3Ds were produced between 1959 and 1985. M ...
commercial engines, and a later reduction in the endurance requirement led to retention of the JT3D engines in production.Taylor et al. 1976, p.246 The first EC-137 made its maiden flight on 9 February 1972, with the fly-off between the two radars taking place from March to July of that year. Favorable test results led to the selection of Westinghouse's radar for the production aircraft.Davies 2005, pp. 5–6. Hughes' radar was initially thought to be a certain winner due to its related development of the APG-63 radar for the new
F-15 Eagle The McDonnell Douglas F-15 Eagle is an American twin-engine, all-weather tactical fighter aircraft designed by McDonnell Douglas (now part of Boeing). Following reviews of proposals, the United States Air Force selected McDonnell Dougla ...
. The Westinghouse radar used a pipelined
fast Fourier transform A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in t ...
(FFT) to digitally resolve 128 Doppler frequencies, while Hughes's radars used analog filters based on the design for the F-15. Westinghouse's engineering team won this competition by using a programmable 18-
bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented a ...
computer whose software could be modified before each mission. This computer was the AN/AYK-8 design from the B-57G program, and designated AYK-8-EP1 for its much expanded memory. This radar also multiplexed a beyond-the-horizon (BTH) pulse mode that could complement the pulse-Doppler radar mode. This proved to be beneficial especially when the BTH mode is used to detect ships at sea when the radar beam is directed below the horizon.


Full-scale development

Approval was given on 26 January 1973 for the full-scale development of the AWACS system. To allow further development of the aircraft's systems, orders were placed for three preproduction aircraft, the first of which performed its maiden flight in February 1975. IBM and Hazeltine were selected to develop the mission computer and display system. The IBM computer was designated 4PI, and the software was written in JOVIAL. A
Semi-Automatic Ground Environment The Semi-Automatic Ground Environment (SAGE) was a system of large computers and associated networking equipment that coordinated data from many radar sites and processed it to produce a single unified image of the airspace over a wide area. SA ...
(SAGE) or back-up interceptor control (BUIC) operator would immediately be at home with the track displays and tabular displays, but differences in symbology would create compatibility problems in tactical ground radar systems in
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
, mainland Europe, and South Korea over Link-11 (TADIL-A). In 1977, Iran placed an order for ten E-3s, however this order was cancelled following the
Iranian Revolution The Iranian Revolution ( fa, انقلاب ایران, Enqelâb-e Irân, ), also known as the Islamic Revolution ( fa, انقلاب اسلامی, Enqelâb-e Eslâmī), was a series of events that culminated in the overthrow of the Pahlavi dyna ...
. Engineering, test and evaluation began on the first E-3 Sentry in October 1975. Between 1977 and 1992, a total of 68 E-3s were built.


Future status

Because the Boeing 707 is no longer in production, the E-3 mission package has been fitted into the Boeing E-767 for the Japan Air Self Defense Forces. The E-10 MC2A was intended to replace USAF E-3s—along with the RC-135 and the
E-8 Joint STARS The Northrop Grumman E-8 Joint Surveillance Target Attack Radar System (Joint STARS) is a United States Air Force airborne ground surveillance, battle management and command and control aircraft. It tracks ground vehicles and some aircraft, c ...
, but the program was canceled by the Department of Defense. NATO intends to extend the operational status of its AWACS until 2035 when it is due to be replaced by the
Alliance Future Surveillance and Control An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
(AFSC) program.NATO summit Warsaw July 2016 The
Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...
(RAF) chose to limit investment in its E-3D fleet in the early 2000s, diverting Sentry upgrade funds to a replacement program. On 22 March 2019, the UK Defence Secretary announced a $1.98 billion contract to purchase five E-7 Wedgetails. The U.S. Air Force intends to retire 15 of its 31 E-3s and acquire the E-7.


Design


Overview

The E-3 Sentry's airframe is a modified Boeing 707-320B Advanced model. Modifications include a rotating radar dome ( rotodome), uprated hydraulics from 241 to 345 bar (3500–5000 PSI) to drive the rotodome, single-point ground refueling, air refueling, and a bail-out tunnel or chute. A second bail-out chute was deleted to cut mounting costs. USAF and NATO E-3s have an unrefueled range of or 8 hours of flying. The newer E-3 versions bought by France, Saudi Arabia, and the UK are equipped with newer CFM56-2 turbofan engines, and these can fly for about 11 hours or more than . The Sentry's range and on-station time can be increased through air-to-air refueling and the crews can work in shifts by the use of an on-board crew rest and meals area. The aircraft are equipped with one toilet in the rear, and a urinal behind the cockpit. Saudi E-3s were delivered with an additional toilet in the rear. When deployed, the E-3 monitors an assigned area of the battlefield and provides information for commanders of air operations to gain and maintain control of the battle; while as an air defense asset, E-3s can detect, identify, and track airborne enemy forces far from the boundaries of the U.S. or NATO countries and can direct interceptor aircraft to these targets. In support of air-to-ground operations, the E-3 can provide direct information needed for interdiction, reconnaissance, airlift, and close-air support for friendly ground forces.


Avionics

The unpressurized rotodome is in diameter, thick at the center, and is held above the fuselage by 2 struts. It is tilted down at the front to reduce its aerodynamic drag, which lessens its detrimental effect on take-offs and endurance. This tilt is corrected electronically by both the radar and
secondary surveillance radar Secondary surveillance radar (SSR)''Secondary Surveillance Radar'', Stevens M.C. Artech House, is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the de ...
antenna
phase shifter A phase shift module is a microwave network module which provides a controllable phase shift of the RF signal. Phase shifters are used in phased arrays. Classification Active versus passive Active phase shifters provide gain, while passive ...
s. The rotodome uses
bleed air Bleed air is compressed air taken from the compressor stage of a gas turbine upstream of its fuel-burning sections. Automatic air supply and cabin pressure controller (ASCPCs) valves bleed air from high or low stage engine compressor sections. Lo ...
, outside cooling doors, and fluorocarbon-based cold plate cooling to maintain the electronic and mechanical equipment temperatures. The hydraulically rotated antenna system permits the and AN/APY-2 passive electronically scanned array radar system to provide surveillance from the Earth's surface up into the
stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...
, over land or water. Other major subsystems in the E-3 Sentry are navigation, communications, and computers. 14 consoles display computer-processed data in graphic and tabular format on screens. Its operators perform surveillance, identification, weapons control, battle management and communications functions. Data may be forwarded in real-time to any major
command and control Command and control (abbr. C2) is a "set of organizational and technical attributes and processes ... hatemploys human, physical, and information resources to solve problems and accomplish missions" to achieve the goals of an organization or e ...
center in rear areas or aboard ships. In times of crisis, data may also be forwarded to the
National Command Authority National Command Authority may refer to: * National Command Authority (Pakistan) * National Command Authority (United States) National Command Authority (NCA) is a term that was used by the Department of Defense of the United States of America to ...
in the U.S. via RC-135 or aircraft carrier task forces.
Electrical generator In electricity generation, a generator is a device that converts motive power (mechanical energy) or fuel-based power (chemical energy) into electric power for use in an external electrical circuit, circuit. Sources of mechanical energy include s ...
s mounted in each of the E-3's four engines provide 1
megawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after Jame ...
of electrical power required by the aircraft's radars and electronics. Its pulse-Doppler radar has a range of more than 250 mi (400 km) for low-flying targets at its operating altitude, and the pulse (BTH) radar has a range of approximately 400 mi (650 km) for aircraft flying at medium to high altitudes. The radar, combined with a
secondary surveillance radar Secondary surveillance radar (SSR)''Secondary Surveillance Radar'', Stevens M.C. Artech House, is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the de ...
(SSR) and
electronic support measures In military telecommunications, electronic support (ES) or electronic support measures (ESM) gather intelligence through passive "listening" to electromagnetic radiations of military interest. They are an aspect of electronic warfare involving ac ...
(ESM), provides a
look down To look is to use sight to perceive an object. Look or The Look may refer to: Businesses and products * Look (modeling agency), an Israeli modeling agency * ''Look'' (American magazine), a defunct general-interest magazine * ''Look'' (UK m ...
capability, to detect, identify, and track low-flying aircraft, while eliminating ground clutter returns.


Upgrades

Between 1987 and 2001, USAF E-3s were upgraded under the "Block 30/35 Modification Program". Enhancements included: *The installation of ESM and an electronic surveillance capability, for both active and passive means of detection. *Installation of the Joint Tactical Information Distribution System (JTIDS), which provides rapid and secure communication for transmitting information, including target positions and identification data, to other friendly platforms. * Global Positioning System (GPS) capability was added. *Onboard computers were overhauled to accommodate JTIDS,
Link-16 Link 16 is a military tactical data link network used by NATO and nations allowed by the MIDS International Program Office (IPO). Its specification is part of the family of Tactical Data Links. With Link 16, military aircraft as well as ships ...
, the new ESM systems and to allow for future enhancements.


RSIP

The Radar System Improvement Program (RSIP) was a joint US/NATO development program. RSIP enhances the operational capability of the E-3 radars'
electronic countermeasures An electronic countermeasure (ECM) is an electrical or electronic device designed to trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used both offensively and defensively to deny targeting inf ...
, and improves the system's reliability, maintainability, and availability. Essentially, this program replaced the older transistor-transistor logic (TTL) and
emitter-coupled logic In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven bipolar junction transistor (BJT) differential amplifier with single-ended input and limited emitter current to ...
(MECL) electronic components, long-since out of production, with off-the-shelf computers that utilised a
High-level programming language In computer science, a high-level programming language is a programming language with strong abstraction from the details of the computer. In contrast to low-level programming languages, it may use natural language ''elements'', be easier to ...
instead of assembly language. Significant improvement came from adding
pulse compression Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. This is achieved by modulating the transmitted pulse and then correlating th ...
to the pulse-Doppler mode. These hardware and software modifications improve the E-3 radars' performance, providing enhanced detection with an emphasis towards low
radar cross-section Radar cross-section (RCS), also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. An object reflects a limited amount of radar energy back to the source. ...
(RCS) targets. The RAF had also joined the USAF in adding RSIP to upgrade the E-3's radars. The retrofitting of the E-3 squadrons was completed in December 2000. Along with the RSIP upgrade was installation of the Global Positioning System/Inertial Navigation Systems which improved positioning accuracy. In 2002, Boeing was awarded a contract to add RSIP to the small French AWACS squadron. Installation was completed in 2006. Saudi Arabia began RSIP upgrades in 2013; the first aircraft being upgraded by Boeing in Seattle with the four remaining aircraft upgraded in Riyadh between 2014 and 2016.


NATO Mid Term Program

Between 2000 and 2008 NATO upgraded its E-3s to ''Mid Term Program'' (MTP) standard. This involved technical upgrades and a total multi-sensor-systems integration


DRAGON

In 2009, the USAF, in cooperation with NATO, entered into a major flight deck avionics modernization program in order to maintain compliance with worldwide airspace mandates. The program, called DRAGON (for DMS Replacement of Avionics for Global Operation and Navigation), was awarded to Boeing and
Rockwell Collins Rockwell Collins was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Radio C ...
in 2010. Drawing on their Flight2
flight management system A flight management system (FMS) is a fundamental component of a modern airliner's avionics. An FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew to the point that mod ...
(FMS), almost all the avionics were replaced with more modern digital equipment from Rockwell Collins. Main upgrades include a Digital Audio Distribution System, Mode-5/ ADS-B transponder, Inmarsat and VDL datalinks, and a
terrain awareness and warning system In aviation, a terrain awareness and warning system (TAWS) is generally an on-board system aimed at preventing unintentional impacts with the ground, termed "controlled flight into terrain" accidents, or CFIT.Federal Aviation AdministrationInsta ...
(TAWS). The centerpiece flight deck hardware consists of five 6x8 color graphics displays and two color CDUs. DRAGON laid the foundation for subsequent upgrades including GPS M-Code, Iridium ATC, and Autopilot. USAF DRAGON Production began in 2018.


USAF Block 40/45

In 2014 the USAF began upgrading block 30/35 E-3B/Cs into block 40/45 E-3Gs. This upgrade replaces the main flight computer with a
Red Hat Linux Red Hat Linux was a widely used commercial open-source Linux distribution created by Red Hat until its discontinuation in 2004. Early releases of Red Hat Linux were called Red Hat Commercial Linux. Red Hat published the first non-beta release ...
-based system, as well as replacing the DOS 2.0-like operating system with a
Windows 95 Windows 95 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of operating systems. The first operating system in the 9x family, it is the successor to Windows 3.1x, and was released to manufactu ...
-like system on the operator workstations. In 2016, a three-week long cybersecurity vulnerability test revealed that the 40/45 block and its supporting ground equipment were vulnerable to cyber threats, and were thus deemed "not survivable." This caused a delay of approximately two years. Twenty-four E-3s are projected to complete this upgrade to 40/45 by the end of
fiscal year A fiscal year (or financial year, or sometimes budget year) is used in government accounting, which varies between countries, and for budget purposes. It is also used for financial reporting by businesses and other organizations. Laws in many ju ...
2020, while seven aircraft will be retired to save upgrade costs and harvest out-of-production components.


NATO Final Lifetime Extension Program

NATO intends to extend the operational status of its AWACS until 2035 by significantly upgrading fourteen aircraft in the ''Final Lifetime Extension Program'' (FLEP) between 2019 and 2026. Upgrades include the expansion of data capacity, expansion of bandwidth for satellite communications, new encryption equipment, new HAVE QUICK radios, upgraded mission computing software and new operator consoles. The supporting ground systems (mission training center and mission planning and evaluation system) will also be upgraded to the latest standard. NATO Airborne Early Warning & Control Program Management Agency (NAPMA) is the preparing and executing authority for the FLEP. FLEP will be combined with the standard planned higher echelon technical maintenance.


Operational history


USA

In March 1977 the 552nd Airborne Warning and Control Wing received the first E-3 aircraft at
Tinker AFB Tinker Air Force Base is a major United States Air Force base, with tenant U.S. Navy and other Department of Defense missions, located in Oklahoma County, Oklahoma, surrounded by Del City, Oklahoma City, and Midwest City. The base, origin ...
, Oklahoma. The 34th and last USAF Sentry was delivered in June 1984. The USAF has a total of thirty-one E-3s in active service. Twenty-seven are stationed at Tinker AFB and belong to the
Air Combat Command Air Combat Command (ACC) is one of nine Major Commands (MAJCOMs) in the United States Air Force, reporting to Headquarters, United States Air Force (HAF) at the Pentagon. It is the primary provider of air combat forces for the Air Force, and i ...
(ACC). Four are assigned to the
Pacific Air Forces Pacific Air Forces (PACAF) is a Major Command (MAJCOM) of the United States Air Force and is also the air component command of the United States Indo-Pacific Command (USINDOPACOM). PACAF is headquartered at Joint Base Pearl Harbor–Hickam ( ...
(PACAF) and stationed at Kadena AB, Okinawa and
Elmendorf AFB Elmendorf Air Force Base is a United States Air Force (USAF) facility in Anchorage, Alaska. Originally known as Elmendorf Field, it became Elmendorf Air Force Base after World War II. It is the home of the Headquarters, Alaskan Air Command (AL ...
, Alaska. One aircraft (TS-3) was assigned to Boeing for testing and development (retired/scrapped June 2012). E-3 Sentry aircraft were among the first to deploy during
Operation Desert Shield The Gulf War was a 1990–1991 armed campaign waged by a 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Iraq were carried out in two key phases: ...
, where they established a radar screen to monitor Iraqi forces. During Operation Desert Storm, E-3s flew 379 missions and logged 5,052 hours of on-station time.Veronico and Dunn 2004, p. 83. The data collection capability of the E-3 radar and computer subsystems allowed an entire air war to be recorded for the first time. In addition to providing senior leadership with time-critical information on the actions of enemy forces, E-3 controllers assisted in 38 of the 41 air-to-air kills recorded during the conflict. NATO, UK, French and USAF AWACS played an important role in the air campaign against
Serbia Serbia (, ; Serbian: , , ), officially the Republic of Serbia (Serbian: , , ), is a landlocked country in Southeastern and Central Europe, situated at the crossroads of the Pannonian Basin and the Balkans. It shares land borders with Hung ...
and
Montenegro ) , image_map = Europe-Montenegro.svg , map_caption = , image_map2 = , capital = Podgorica , coordinates = , largest_city = capital , official_languages = ...
in the former republic of
FR Yugoslavia Serbia and Montenegro ( sr, Cрбија и Црна Гора, translit=Srbija i Crna Gora) was a country in Southeast Europe located in the Balkans that existed from 1992 to 2006, following the breakup of the Socialist Federal Republic of Yu ...
. From March to June 1999 the aircraft were deployed in the
NATO bombing of Yugoslavia The North Atlantic Treaty Organization (NATO) carried out an aerial bombing campaign against the Federal Republic of Yugoslavia during the Kosovo War. The air strikes lasted from 24 March 1999 to 10 June 1999. The bombings continued until an ...
(operation Allied Force) directing allied strike and air defence aircraft to and from their targets. Over 1,000 aircraft operating from bases in
Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...
and
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
took part in the air campaign which was intended to destroy Yugoslav air defenses and high-value targets such as the bridges across the
Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , ...
river, factories, power stations, telecommunications facilities, and military installations. On 18 November 2015, an E-3G was deployed to the Middle East to begin flying combat missions in support of Operation Inherent Resolve against ISIL, marking the first combat deployment of the upgraded Block 40/45 aircraft.


United Kingdom

In February 1987 the UK and France ordered E-3 aircraft in a joint project which saw deliveries start in 1991. The British requirement arose due to the cancellation of the BAE Nimrod AEW3 project. France operates its E-3F aircraft independently of NATO, UK E-3Ds formed the E-3D Component of the NATO Airborne Early Warning and Control Force (NAEWCF), receiving much of their tasking directly from NATO. However, RAF E-3Ds remain UK manned and capable of independent, national tasking. This has been done on numerous occasions, notably when E-3Ds were committed to operations over Afghanistan in 2001 and Iraq in 2003. The UK fleet has slowly been reduced from 7 since 2011. In 2009, the UK effectively limited the service life of the E-3D fleet by de-funding the Project Eagle upgrade which would have seen it upgraded in line with the USAF Block 40/45 standard. ''AirForces Monthly'' reported that by December 2020, just 2 aircraft were available for operations at any one time. The
Strategic Defence and Security Review 2015 The National Security Strategy and Strategic Defence and Security Review 2015 was published by the British government during the second Cameron ministry on 23 November 2015 to outline the United Kingdom's defence strategy up to 2025. It identified k ...
had announced the intention to retain the E-3D fleet until 2035, however in March 2019, the Ministry of Defence announced that the E-3Ds would be replaced by five E-7 Wedgetails from 2023. The £1.51 billion contract was awarded to Boeing without a competitive procurement process, a decision criticised by both competitors of Boeing and the UK's Defence Select Committee. The 2021 Integrated Defence Review confirmed a reduced order of three aircraft. On 27 January 2015, the RAF deployed an E-3D Sentry to Cyprus in support of U.S.-led coalition airstrikes against
Islamic State An Islamic state is a state that has a form of government based on Islamic law (sharia). As a term, it has been used to describe various historical polities and theories of governance in the Islamic world. As a translation of the Arabic term ...
militants in Iraq and Syria. The last intended operational flight by an RAF E3 Sentry was supposed to be in July 2021 with the Sentry retired from service, however RAF ZH101 and ZH106 have both flown patrols over Poland / Eastern Europe during Russia's incursions into Ukraine during late February / March 2022.


France

In February 1987 the UK and France ordered E-3 aircraft in a joint project which saw deliveries start in 1991. France operates its E-3F aircraft independently of NATO, UK E-3Ds formed the E-3D Component of the NATO Airborne Early Warning and Control Force (NAEWCF), receiving much of their tasking directly from NATO. France operates four aircraft, all fitted with the newer CFM56-2 engines.


Chile

3 Boeing E-3D Sentry (Sentry AEW.1) aircraft, acquired second hand from the United Kingdom in September of 2021, arrived in Chile in July of 2022; units ZH103 and ZH106 will join the "Grupo de Aviación N.º 10" of the II Air Brigade.


NATO

NATO acquired 18 E-3As and support equipment, with the first aircraft delivered in January 1982.Wilson 1998, p 75. The aircraft are registered in
Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy of Luxembourg, ; french: link=no, Grand-Duché de Luxembourg ; german: link=no, Großherzogtum Luxemburg is a small land ...
. The eighteen E-3s were operated by Number 1, 2 and 3 Squadrons of NATO's E-3 Component, based at
NATO Air Base Geilenkirchen NATO Air Base Geilenkirchen (E-3A Component) is located near Geilenkirchen, North Rhine-Westphalia, Germany. It is the main operating base of the NATO Boeing E-3 Sentry Component, one of two operational elements of the NATO Airborne Early Warnin ...
. NATO E-3s participated in
Operation Eagle Assist Operation Eagle Assist was a NATO operation where AWACS aircraft patrolled the skies over the United States following the September 11 attacks. On October 4, about a month after the September 11 attacks, the North Atlantic Council decided to ope ...
after the
September 11 attacks The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commerc ...
on the World Trade Center towers and the Pentagon. NATO and RAF E-3s participated in the military intervention in Libya. Presently, 16 NATO E-3As are in the inventory, since one E-3 was lost in a crash and one was retired from service in 2015. The latter was due for its six-year cycle Depot Level Maintenance (DLM) inspection which would have been very costly. The "449 Retirement Project" resulted in reclamation of critical parts with a value of upwards of $40 million which will be used to support the 16 active aircraft. Some of the parts to be removed are no longer on the market or have become very expensive.


Variants

;EC-137D :2 prototype AWACS aircraft with JT3D engines, 1 fitted with a Westinghouse Electric radar and 1 with a Hughes Aircraft Company radar. Both converted to E-3A standard with TF33 engines. ;E-3A :Production aircraft with TF33 engines and AN/APY-1 radar, 24 built for USAF (later converted to E-3B standard), total of 34 ordered but the last 9 completed as E-3C.Pither 1998, pp. 40–42 One additional aircraft retained by Boeing for testing, 18 built for NATO with TF33 engines and 5 for Saudi Arabia with CFM56 engines. ;KE-3A :These are not AWACS aircraft but CFM56 powered tankers based on the E-3 design. 8 were sold to Saudi Arabia. ;RE-3A :Three KE-3 airframes delivered as CFM56–powered strategic reconnaissance aircraft. Systems and external appearance are similar to the USAF’s RC-135V/W Rivet Joint platform. At least one of the RE-3As has received the extended "hog nose" as fitted to the RC-135. ;E-3B :USAF Block 30 modification. E-3As with improvements, 24 conversions. ;E-3C :USAF Block 35 modification. Production aircraft with AN/APY-2 radar, additional electronic consoles and system improvements, ten built. ;JE-3C :One E-3A aircraft used by Boeing for trials later redesignated E-3C. ;E-3D :Production aircraft for the RAF to E-3C standard with CFM56 engines and British modifications designated ''Sentry AEW.1'', 7 built. Modifications included the addition of a refuelling probe next to the existing boom AAR recipticle, CFM-56 engines, wingtip ESM pods, an enhanced Maritime Surveillance Capability (MSC) offering Maritime Scan-Scan Processing (MSSP), JTIDS and Havequick 2 radios. ;E-3F :Production aircraft for the French Air and Space Force to E-3C standard with CFM56 engines and French modifications, 4 built. ;E-3G :USAF Block 40/45 modification. Includes hardware and software upgrades to improve communications, computer processing power, threat tracking, and others, and automates some previously manual functions. Initial operating capability (IOC) declared in July 2015. E-3G(II) Block 40/45 modification that included a glass cockpit modification that reduced the crew size by one, and added a new avionics suite.


Operators

;: The
Chilean Air Force "With full speed to the stars" , colours = Indigo White , colours_label = , march = Alte Kameraden , mascot = , anniversaries = 21 March ...
purchased three retired E-3D Sentry aicraft from the
Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...
. ;: The
French Air and Space Force The French Air and Space Force (AAE) (french: Armée de l'air et de l'espace, ) is the air and space force of the French Armed Forces. It was the first military aviation force in history, formed in 1909 as the , a service arm of the French Arm ...
purchased four E-3F aircraft. * ''
Escadron de détection et de contrôle aéroportés 36 Berry Escadron de détection et de contrôle aéroportés 36 Berry is a French Air and Space Force (Armée de l'air et de l'espace) Airborne Detection and Control Squadron located at BA 702 Avord Air Base, Cher Cher (; born Cherilyn Sarkisian; M ...
'' (36th Airborne Detection and Control Squadron "Berry") based at
Avord Air Base Avord Air Base or BA 702 (french: Base Aérienne 702 Capitaine Georges Madon), named after Captain Georges Madon, is a base of the French Air and Space Force (Armée de l'air et de l'espace) located north northwest of Avord in central France ...
. ; : 18 E-3 AWACS were purchased – 1 was written off in
Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders wit ...
, 3 were retired from service. Mainly responsible for monitoring European NATO airspace, they have also been deployed outside the area in support of NATO commitments. The 20 multinational crews are provided by 15 of the 28 NATO member states. * NATO Airborne Early Warning and Control Force – E-3A Component. Based at Geilenkirchen (Germany), with forward operating bases at
Konya Konya () is a major city in central Turkey, on the southwestern edge of the Central Anatolian Plateau, and is the capital of Konya Province. During antiquity and into Seljuk times it was known as Iconium (), although the Seljuks also called it D ...
(Turkey), Preveza/Aktion (Greece) and Trapani/Birgi (Italy) and a forward operating location at
Ørland Ørland is a municipality in Trøndelag county, Norway. It is part of the Fosen region. Ørland is located at the southwestern tip of the Fosen peninsula at the northern shore of the mouth of Trondheimsfjord where the Stjørnfjorden arm begin ...
(Norway). ** Aircrew Training Squadron ** Flying Squadron 1 ** Flying Squadron 2 ** Flying Squadron 3 – disbanded in 2015 ;: The
Royal Saudi Air Force The Royal Saudi Air Force ( ar, ‎الْقُوَّاتُ الْجَوِّيَّةُ الْمَلَكِيَّةْ ٱلسُّعُوْدِيَّة, Al-Quwwat Al-Jawiyah Al-Malakiyah as-Su’udiyah) (RSAF) is the Military aviation, aviation branch o ...
purchased five E-3A aircraft in 1983. In 2004, modifications began to convert KE-3A tankers into RE-3 electronic intelligence gathering aircraft. * RSAF No. 6 Wing (
Prince Sultan Air Base Prince Sultan Air Base ( ar, قاعدة الأمير سلطان الجوية) (PSAB) is a military air base located in the closed-city of Al Kharj, Saudi Arabia. History There was formerly a large United States presence there during Opera ...
Al Kharj) ::''السرب الثامن عشر'' (''al-Sarab al-Ththamin Eshr'' – No. 18 Squadron) ::No. 19 Squadron – RE-3A/B (as well as Beechcraft 350ER-ISR) ::No. 23 Squadron – KE-3A ;: The
United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army S ...
has 31 operational E-3s as of December 2019 :
Tactical Air Command Tactical Air Command (TAC) is an inactive United States Air Force organization. It was a Major Command of the United States Air Force, established on 21 March 1946 and headquartered at Langley Air Force Base, Virginia. It was inactivated on 1 J ...
1976–1992 :
Air Combat Command Air Combat Command (ACC) is one of nine Major Commands (MAJCOMs) in the United States Air Force, reporting to Headquarters, United States Air Force (HAF) at the Pentagon. It is the primary provider of air combat forces for the Air Force, and i ...
1992–present *
552d Air Control Wing The 552d Air Control Wing is an operational wing of the United States Air Force. It has been based at Tinker Air Force Base, Oklahoma since July 1976, operating the Boeing E-3 Sentry. It includes the 552d Operations Group, 552d Maintenance Gro ...
Tinker Air Force Base Tinker Air Force Base is a major United States Air Force base, with tenant U.S. Navy and other Department of Defense missions, located in Oklahoma County, Oklahoma, surrounded by Del City, Oklahoma City, and Midwest City. The base, origin ...
, Oklahoma :: 960th Airborne Air Control Squadron 2001–present ( NAS Keflavik,
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
1979–1992) ::
963d Airborne Air Control Squadron The 963d Airborne Air Control Squadron is a squadron of the United States Air Force based at Tinker Air Force Base, Oklahoma. The squadron is a subordinate unit of the 552d Operations Group and it flies the Boeing E-3 Sentry radar surveillance ...
1976–present :: 964th Airborne Air Control Squadron 1977–present ::
965th Airborne Air Control Squadron The 965th Airborne Air Control Squadron is part of the 552d Air Control Wing at Tinker Air Force Base, Oklahoma. It operates Boeing E-3 Sentry aircraft conducting airborne command and control missions. The first two antecedents of the squadro ...
1978–1979, 1984–present ::
966th Airborne Air Control Squadron The 966th Airborne Air Control Squadron is an active United States Air Force unit is assigned to the 552d Training Group, 552d Air Control Wing at Tinker Air Force Base, Oklahoma. It operates the E-3 Sentry (AWACS) aircraft conducting airborn ...
1976–present *
380th Air Expeditionary Wing The 380th Air Expeditionary Wing (380 AEW) is a provisional unit of the United States Air Force Air Combat Command (ACC). It is attached to the United States Air Forces Central Command component of ACC and is stationed at Al Dhafra Air Base, Uni ...
2002–present Al Dhafra Air Base, United Arab Emirates *
968th Expeditionary Airborne Air Control Squadron The 968th Expeditionary Airborne Air Control Squadron (968 EAACS) is a provisional unit of the United States Air Force, flying the Boeing E-3G Sentry. Since March 2022, the squadron is stationed at Prince Sultan Air Base, Saudi Arabia. It has ...
2013–present (
Thumrait Air Base RAFO Thumrait airbase is a military airport located near Thumrait, a town in Dhofar Governorate, Oman. The Royal Air Force of Oman (RAFO) are the operators of RAFO Thumrait, and is home to two RAFO squadrons of F16s. The United States Air Force ...
,
Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of ...
2002–2003) :
Air Force Reserve Command The Air Force Reserve Command (AFRC) is a major command (MAJCOM) of the United States Air Force, with its headquarters at Robins Air Force Base, Georgia. It is the federal Air Reserve Component (ARC) of the U.S. Air Force, consisting of commi ...
*
513th Air Control Group The 513th Air Control Group is an Air Reserve Component unit of the United States Air Force. It is assigned to the Tenth Air Force, Air Force Reserve Command, and is stationed at Tinker Air Force Base, Oklahoma. The group's mission is to prov ...
(Associate) – Tinker AFB, Oklahoma :: 970th Airborne Air Control Squadron 1996–present (Personnel only, aircraft loaned by co-located 552nd ACW as needed) *
413th Flight Test Group The 413th Flight Test Group (413 FTG) is a United States Air Force Air Force Reserve Command unit. It is stationed at Robins Air Force Base, Georgia as a tenant unit. The 413 FTG conducts flight tests on aircraft after the programmed depot ma ...
– Robins AFB, Georgia ::
10th Flight Test Squadron The 10th Flight Test Squadron is part of the 413th Flight Test Group of Air Force Materiel Command based at Tinker Air Force Base, Oklahoma. It performs acceptance testing on refurbished Rockwell B-1 Lancer, Boeing B-52 Stratofortress, Boei ...
– Tinker AFB, Oklahoma 1994–present :
Pacific Air Forces Pacific Air Forces (PACAF) is a Major Command (MAJCOM) of the United States Air Force and is also the air component command of the United States Indo-Pacific Command (USINDOPACOM). PACAF is headquartered at Joint Base Pearl Harbor–Hickam ( ...
* 3d Wing
Elmendorf AFB Elmendorf Air Force Base is a United States Air Force (USAF) facility in Anchorage, Alaska. Originally known as Elmendorf Field, it became Elmendorf Air Force Base after World War II. It is the home of the Headquarters, Alaskan Air Command (AL ...
,
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...
:: 962d Airborne Air Control Squadron 1986–present *
18th Wing The United States Air Force's 18th Wing is the host wing for Kadena Air Base, Okinawa, Japan and is the Air Force's largest combat wing. It is the largest and principal organization in the Pacific Air Forces Fifth Air Force. The Wing's 18th Ope ...
Kadena AB, Japan ::
961st Airborne Air Control Squadron The 961st Airborne Air Control Squadron (961 AACS) is part of the 18th Wing at Kadena Air Base, Japan. It operates the E-3 Sentry aircraft conducting airborne command and control missions. Mission Provide airborne command and control, long-ran ...
1979–present


Former operators

;: The
Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...
purchased seven E-3Ds by October 1987, designated ''Sentry AEW.1'' in British service. As of December 2020, only three remained in service after one was withdrawn from service in 2009 to be used as spares, two were withdrawn in March 2019 and a further one withdrawn in January 2020. The fleet had been given an out of service date (OSD) of December 2022. They form the E-3D Component of the NATO Airborne Early Warning and Control Force. However, that date was accelerated pursuant to the 2021 defence review and the aircraft made its final flight in U.K. service in August 2021. *
RAF Waddington Royal Air Force Waddington otherwise known as RAF Waddington is a Royal Air Force (RAF) station located beside the village of Waddington, south of Lincoln, Lincolnshire in England. The station is the RAF's Intelligence Surveillance Target ...
,
Lincolnshire Lincolnshire (abbreviated Lincs.) is a county in the East Midlands of England, with a long coastline on the North Sea to the east. It borders Norfolk to the south-east, Cambridgeshire to the south, Rutland to the south-west, Leicestershir ...
, England :: No. 8 Squadron (1991–2021) :: No. 23 Squadron (1996–2009) :: No. 54 Squadron (Operational Conversion Unit 2005–?) :: No. 56 Squadron (Operational Evaluation Unit 2008–?)


Incidents and accidents

E-3s have been involved in three hull-loss accidents, and one radar antenna was destroyed during RSIP development (see photo under Avionics). * On 22 September 1995, a U.S. Air Force E-3 Sentry (callsign Yukla 27, serial number 77-0354), crashed shortly after takeoff from Elmendorf AFB, Alaska. The plane lost power to both left side engines after ingesting several
Canada geese The Canada goose (''Branta canadensis''), or Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is ...
during takeoff. The aircraft went down about northeast of the runway, killing all 24 crew members on board. * On 14 July 1996, a NATO E-3 Sentry (tail number LX-N90457) overran the runway and crashed into a sea wall at Préveza-Aktion Airport in Greece when the pilot attempted to abort takeoff after mistakenly believing that the aircraft had suffered a bird strike. The aircraft overran the runway and struck a sea wall, where it came to a halt. There were no injuries and the aircraft was written off. Investigators could find no evidence that a bird strike and ingestion had occurred. * On 28 August 2009, a U.S. Air Force E-3C Sentry (serial number 83-0008) participating in a Red Flag exercise at
Nellis Air Force Base Nellis Air Force Base ("Nellis" colloq.) is a United States Air Force installation in southern Nevada. Nellis hosts air combat exercises such as Exercise Red Flag and close air support exercises such as Green Flag-West flown in " Military ...
, Nevada experienced a nose gear collapse on landing, resulting in a fire and damaging the aircraft beyond repair. All 32 crew members evacuated safely.


Specifications (USAF/NATO)


See also


References

Notes Citations Bibliography * * * * * * * *


External links


Royal Air Force E-3 Sentry information

NATO AWACS-Spotter Geilenkirchen website

Airborne Early Warning Association website
{{USAF system codes Aircraft first flown in 1972 AWACS aircraft E-03 Sentry Boeing 707 E-03 Sentry Quadjets 1970s United States military reconnaissance aircraft