Airborne early warning and control
An airborne early warning and control (AEW&C) system is an airborne radar system designed to detect aircraft, ships and vehicles at long ranges and control and command the battle space in an air engagement by directing fighter and attack aircraft strikes. AEW&C units are also used to carry out surveillance, including over ground targets and frequently perform C2BM (command and control, battle management) functions similar to an Airport Traffic Controller given military command over other forces. Used at a high altitude, the radars on the aircraft allow the operators to distinguish between friendly and hostile aircraft hundreds of miles away.
AEW&C aircraft are used for both defensive and offensive air operations, and are to the NATO and USA forces trained or integrated Air Forces what the Command Information Center is to a Navy Warship, plus a highly mobile and powerful radar platform. The system is used offensively to direct fighters to their target locations, and defensively, directing counterattacks on enemy forces, both air and ground. So useful is the advantage of command and control from a high altitude, the United States Navy operates AEW&C aircraft off its Supercarriers to augment and protect its carrier Command Information Centers (CICs)
AEW&C is also known by the older terms "airborne early warning" (AEW) and "airborne warning and control system" (AWACS, pron.: // AY-waks) although AWACS is the name of a specific system currently used by NATO and the USAF and is often used in error to describe similar systems.
General characteristics 
Modern AEW&C systems can detect aircraft from up to 250 miles (400 km) away, well out of range of most surface-to-air missiles. One AEW&C aircraft flying at 30,000 feet (9,100 m) can cover an area of 120,460 square miles (312,000 km2). Three such aircraft in overlapping orbits can cover the whole of Central Europe. In air-to-air combat, AEW&C systems can communicate with friendly aircraft, extend their sensor range and give them added stealth, since they no longer need their own active radar to detect threats. However, by the nature of radar, the aircraft can be detected by opposing forces beyond its own detection range. This is because the outgoing pulse reduces in strength the further it travels. Therefore, a signal intended to reflect back must be strong enough to cover at least twice the distance between the sender and the target—more in practice due to absorption losses.
History of development 
As part of their early use of radar, the British developed a radar set that could be carried on an aircraft for "Air Controlled Interception". The intention was to cover the North West approaches where German long range Fw 200 Condor aircraft were a threat to shipping. A Vickers Wellington bomber (serial R1629) was fitted with a rotating antenna array. It was trialled for use against aerial targets and then for possible use against German E boats. Another installation was a radar equipped Wellington used to direct Bristol Beaufighters onto Heinkel He 111s, which were air-launching V-1 flying bombs.
In February 1944 the U.S. Navy ordered the development of a radar system that could be carried aloft in an aircraft as Project Cadillac. A prototype system was built and flown in August on a modified TBM Avenger torpedo bomber. Tests proved successful, with the system being able to detect low flying formations at a range in excess of 100 miles (160 km). The U.S. Navy then ordered production of the TBM-3W, the first production AEW aircraft to enter service. TBM-3Ws fitted with the AN/APS-20 radar entered service in March 1945, with some 36–40 eventually being constructed.
In 1958, the Soviet Tupolev Design Bureau was also ordered to design an AEW aircraft. After trying to fit the projected radar instrumentation in a Tu-95 and a Tupolev Tu-116, the decision was made to use the Tu-114 fuselage instead. This solved the problems with cooling and operator space that existed with the narrower Tu-95 and Tu-116 fuselage. To meet the flight range requirements, the plane was fitted with an air-to-air refueling receiver. The resulting plane, the Tu-126, was used by the Soviet Air Forces until it was replaced by the Beriev A-50 in 1984.
Current systems 
Many countries have developed their own AEW&C systems, although the Boeing E-3 Sentry and Northrop Grumman E-2 Hawkeye are the most common systems worldwide. The E-3 Sentry was built by the Boeing Defense and Space Group (now Boeing Defense, Space & Security) and is based on the Boeing 707-320 aircraft. 65 E-3 were built and it is operated by NATO and four nations. The specially designed Grumman E-2 Hawkeye entered service in 1965 and has been operated by eight different nations. Over 168 have been produced so far and new versions continue to be developed making it the most widely used AEW system. For the Japan Air Self-Defense Force, the E-3 technology has been fitted into the Boeing E-767.
After World War 2, the United Kingdom deployed a substantial AEW capability with American Douglas AD-4W Skyraiders, designated Skyraider AEW.1, which in turn were replaced by the Fairey Gannet AEW.3, using the same AN/APS-20 radar. When the Gannet was withdrawn, the Royal Air Force (RAF) redeployed the radars from the Gannets onto Avro Shackleton MR.2 airframes, redesignated Shackleton AEW.2. To replace the Shackleton AEW.2, an AEW variant of the Hawker Siddeley Nimrod, known as the Nimrod AEW3, was ordered in 1974. However, after a protracted and problematic development, this was cancelled in 1986, and seven E-3Ds, designated Sentry AEW.1 in RAF service, were purchased instead.
The Russian Air Force is currently using around 15–20 Beriev A-50 and A-50U "Shmel" in the AEW role. The "Mainstay" is based on the Ilyushin Il-76 airframe, with a large non-rotating disk radome on the rear fuselage. These replaced the 12 Tupolev Tu-126 that filled the role previously.
In 2003, the Indian Air Force (IAF) and Defence Research and Development Organisation (DRDO) began a study of requirements for developing an Airborne Early Warning and Control (AEWAC) system. The Indian Air Force ordered three EL/W-2090 systems in 2004, the first of which first arrived on May 25, 2009.
The Royal Australian Air Force, Republic of Korea Air Force and the Turkish Air Force are deploying Boeing 737 AEW&C aircraft. Unlike the E-2 and E-3, the Boeing 737 AEW&C does not use a rotating disk radome (rotodome) but instead has a large dorsal fin. It will probably be marketed towards many existing E-2 customers, who would otherwise have no choice but to purchase a system intended for an aircraft carrier, due to lack of options.
In early 2006, the Pakistan Air Force ordered six Erieye AEW equipped Saab 2000 from Sweden for roughly $1bn. In December 2006, the Pakistan Navy requested three excess P-3 Orion aircraft to be equipped with Hawkeye 2000 AEW systems, the overall cost of the program is $855mn. China and Pakistan also signed a memorandum of understanding (MoU) for the joint development of AEW&C systems. A $278m deal has been struck with China.
Israel has developed the IAI/Elta EL/M-2075 Phalcon system, which uses an AESA (Active Electronically Scanned Array) in lieu of a rotodome antenna. The system was the first such system into service. The original Phalcon was mounted on a Boeing 707  and developed for the Israeli Defense Force and for export.
Many AEW systems feature additional command and control capabilities and are often referred to as airborne early warning and control (AEW&C) systems.
Helicopter AEW systems 
The Royal Navy Sea King ASaC7 naval helicopter was operated from Invincible-class aircraft carriers. The creation of Sea King ASaC7, and earlier AEW.2 and AEW.5 is the consequence of lessons learnt by the Royal Navy in the 1982 Falklands War when the lack of AEW coverage for the task force was a major tactical shortcoming. The Spanish Navy fields the SH-3 Sea King in the same role, operated from the carriers Principe de Asturias and Juan Carlos I
The Russian-built Kamov Ka-31 is deployed by the Indian Navy on Krivak-III frigates and reportedly used by the Russian Navy on its sole Kuznetsov aircraft carrier. It is fitted with E-801M Oko (Eye) airborne electronic warfare radar that can track up to 20 targets simultaneously with aerial detection range 90 mi (150 km) and surface warships up to 160 mi (250 km).
Airborne Warning and Control System (AWACS) 
This is a specific system with a rotating radar dome "rotodome" radome designed and built by Boeing (Defense & Space Group) using Westinghouse (now Northrop Grumman) radar. It is mounted on either the E-3 Sentry aircraft (Boeing 707) or more recently a modified Boeing 767. Only the Japanese Air Self-Defense Force has the 767 version, calling it the E-767.
List of AEW&C aircraft types 
- Antonov An-71
- Avro Shackleton AEW.2
- Beriev A-50 Shmel
- Boeing 737 AEW&C
- Boeing B-29 AEW
- Boeing E-3 Sentry
- Boeing E-767
- Boeing PB-1W Flying Fortress
- British Aerospace Nimrod AEW3
- Britten-Norman AEW Defender
- Douglas AD-3W/4W/5W Skyraider
- EADS CASA C-295 AEW
- Embraer R-99A/E-99/EMB 145 AEW&C
- Fairey Gannet AEW.3
- Grumman AF-2W Guardian
- Grumman E-1 Tracer
- Grumman E-2 Hawkeye
- Grumman TBM-3W Avenger
- Gulfstream G550
- HAL 748 Airborne Surveillance Platform
- HESA IrAn-140
- IAI Eitam
- KJ-1 AEWC
- Lockheed EC-121 Warning Star/PO-2W/WV-2
- Lockheed EC-130V Hercules
- Lockheed P-3 AEW&C
- Saab 340 AEW&C (S 100 B/D Argus)
- Saab 2000 AEW&C
- Shaanxi Y-8 AWACS/Y-8J AEW/ZDK-03 AEW&C
- Tupolev Tu-126
- Vickers Wellington "Air Controlled Interception"
- Xian Y-7 AWACS
- AgustaWestland EH101
- Changhe Z-8AEW
- Kamov Ka-31
- Mil Mi-17Z-2 AEW
- Sikorsky SH-3H AEW
- Sikorsky HR2S-1W
- Westland Sea King AEW.2 / AEW5 / ASaC7
See also 
- List of AEW&C aircraft operators
- Airborne Warning and Control System
- Erieye radar
- US/Saudi AWACS Sale
- "AWACS: NATO’s eyes in the sky – How does it work in practice?". Nato.int.
- Air-Britain, Aviation World, 2004
- Hodges, R "Air controlled interception" Radar Development to 1945 R W Burns (ed)
- Flypast April 1987: "The First AWACS"
- "BAe Nimrod AEW 3." Spyflight. Retrieved: 21 October 2010.
- "Development of Airborne Early Warning and Control System" (Press release). Press Information Bureau, GoI. 11 December 2003. Retrieved 2008-07-25.
- "Arms deal underway, first Israeli Phalcon lands in India – Israel News, Ynetnews". Ynetnews.com. June 20, 1995. Archived from the original on 28 May 2009. Retrieved June 1, 2009.
- 07-Apr-2008 11:12 EDT (April 7, 2008). "Sweden Finalizes Saab 2000 AEW&C Contract With Pakistan". Defenseindustrydaily.com. Retrieved June 1, 2009.
- "C4ISRJournal.com". C4ISRJournal.com. December 11, 2006. Retrieved June 1, 2009.
- "$278m AWACS deal struck with China: PAF » www.idrw.org / Indian Defense Research Wing". Idrw.org. Retrieved June 1, 2009.[dead link]
- "B707 Phalcon, "Israeli Weapons.com"". Israeli-weapons.com. Retrieved 2012-03-31.
- April 1987 Flypast Magazine article 'The First AWACS'
|Wikimedia Commons has media related to: Early Warning Aircraft (AEW/AWACS)|
- NATO AWACS-Spotter Geilenkirchen website
- FAS.org E-3 Sentry information
- Boeing AWACS website
- Airborne Early Warning Association website
- TU-126 MOSS AWACS – history of development- in Russian
- Aiborne radar "Gneis-2" – in Russian