The Boeing E-3 Sentry is an American airborne early warning and control (AEW&C) aircraft manufactured by Boeing. Derived from the Boeing 707 airliner, it provides all-weather surveillance, command, control, and communications. The aircraft entered service with the United States Air Force in March 1977. The E-3 is known for its distinctive rotating radar dome mounted above the fuselage.
Development
In 1963, the United States Air Force initiated a requirement to replace its Lockheed EC-121 Warning Star fleet. Boeing, Douglas, and Lockheed submitted aircraft proposals, with Boeing selected in July 1970 using a modified 707 design. In a parallel competition for the radar system, Westinghouse Electric's design was chosen over Hughes Aircraft following fly-off evaluations using two EC-137D testbeds. The first testbed flew on 9 February 1972, and the first preproduction aircraft flew in February 1975. Production began with initial deliveries in 1977 and concluded in 1992 after 68 aircraft were constructed.
Design
The E-3 Sentry uses a modified Boeing 707-320B Advanced airframe fitted with four Pratt & Whitney TF33-PW-100A turbofans or CFM56-2 engines depending on the operator. Electronics and radar systems are powered by four engine-mounted generators producing 1 megawatt of electrical power. Its primary sensor is an AN/APY-1 or AN/APY-2 passive electronically scanned array radar housed inside a 30-foot-diameter, hydraulically rotated dome mounted 11 feet above the fuselage. The radar system provides low-altitude detection out to 250 miles and medium-to-high altitude detection out to 400 miles. Unrefueled endurance is 8 hours for TF33 variants and 11 hours for CFM56 variants, with range extendable via air-to-air refueling.
Operational History
The E-3 entered service with the USAF 552nd Airborne Warning and Control Wing in March 1977. Operational deployments include Operation Desert Storm in 1991, where E-3s flew 379 missions, as well as operations over Yugoslavia, Afghanistan, and Iraq. In addition to the USAF, the aircraft was acquired by NATO, the United Kingdom, France, Saudi Arabia, and second-hand by Chile. Four aircraft have been lost in hull-loss accidents, including a 1995 bird-strike crash at Elmendorf Air Force Base and a ground attack at Prince Sultan Air Base in 2026.
Variants
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E-3A: Initial production variant equipped with Pratt & Whitney TF33 engines and AN/APY-1 radar.
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E-3B: USAF Block 30 modification featuring system enhancements, GPS capability, and Joint Tactical Information Distribution System upgrades.
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E-3C: USAF Block 35 production standard fitted with an AN/APY-2 radar and additional electronic consoles.
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E-3D: RAF production model designated Sentry AEW.1, powered by CFM56 engines and featuring British avionics modifications.
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E-3G: USAF Block 40/45 modification replacing legacy computers and software with Linux- and Windows-based processing architectures.