Airborne Early Warning

United States Air Force E-3 Sentry

An Airborne Early Warning (AEW) system is a radar system carried by an aircraft which is designed to detect other aircraft. Used at a high altitude, the radars allow the operators to distinguish between friendly and hostile aircraft hundreds of miles away.

AEW aircraft are used for defensive and offensive air operations. The system is used offensively to direct fighters to their target locations, and defensively to counter attacks.

Many countries have their own AEW systems, although the E-3 Sentry and Grumman E-2C Hawkeye are the popular systems worldwide. The Sentry was built by the Boeing Defense and Space Group (now Integrated Defense Systems) and is widely considered to be an international benchmark for AEW systems. It is based on the Boeing 707 aircraft. The E-2 Hawkeye, which entered service in 1965, is arguably the most widely used AEW system. The E-3 Sentry is not strictly an AEW system, as it has far more functionality. See Airborne Warning and Control System.

The United Kingdom also developed its own AEW aircraft in the form of the Nimrod AEW.3, developed by De Havilland. However, the Nimrod AEW programme was cancelled just as the prototype completed its final trails in favor of procuring alternative existing models from the US.

The RAAF are deploying Boeing 737-based aircraft under Project Wedgetail. Unlike the E-2 and E-3, Wedgetail does not have a rotodome. 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.

The Swedish Air Force use the S 100B Argus as their AEW platform. The S 100B Argus is based on the Saab 340 with an Ericsson Erieye PS-890 radar.

There are only two helicopter-based AEW platforms in existence. One is the Royal Navy Westland Sea King ASaC7 naval helicopter. It is operated from the Royal Navy's Invincible class aircraft carrier (HMS Illustrious and HMS Ark Royal). The creation of Sea King ASaC7, and earlier AEW.2 and AEW.5 is the consequence of the harsh lessons learnt by the Royal Navy task force sent to the South Atlantic in the 1982 Falklands War. The lack of AEW coverage for the task force was a major tactical shortcoming at the time.

Another Helicopter is Russian Built Ka-31 Helix-B, deployed by Indian Navy on Krivak-III Frigates. It is fitted with E-801M Oko (Eye) airborne electronic warfare radar which can track upto 20 targets simultaneously with aerial detection range 150km and Surface Warships upto 250km.

Some AEW systems feature additional command and control functionality, though not to the level of AWACS aircraft. These are often referred to as Airborne Early Warning and Control (AEW&C) systems.