Boeing E-3 Sentry

The Boeing E-3 Sentry, commonly known as AWACS, is an airborne early warning and control (AEW&C) aircraft developed by Boeing as the prime contractor. Derived from the Boeing 707, it provides all-weather surveillance, command, control and communications, and is used by the United States Air Force (USAF), NATO, Royal Air Force (RAF), French Air Force and Royal Saudi Air Force. The E-3 is distinguished by the distinctive rotating radar dome above the fuselage. Production ended in 1992 after 87 aircraft had been built.

In the mid-1960s, the USAF was seeking an aircraft to replace its piston-engined Lockheed EC-121 Warning Star, which had seen 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's and Hughes's competing radars. Both radars used Pulse-Doppler technology, with Westinghouse's design emerging as the contract winner. Col. Emmett Virgil Conkling who was an early participant in radar development in England prior to the official U.S. entry into WWII, retired from his position with the Air Force in the pentagon and took the position of head of development in Seattle. 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 42 aircraft were manufactured. NATO, as a single identity, also had eighteen aircraft manufactured, basing them in Germany. The E-3 was also sold to the United Kingdom (Twelve) and France (Ten) and Saudi Arabia (five, plus eight E-3 derived tanker aircraft). In 1991, by which time the last aircraft had been delivered, E-3s participated in Operation Desert Storm, playing a crucial role of directing Coalition aircraft against the enemy. Throughout the aircraft's service life, numerous upgrades were performed to enhance its capabilities. In 1996, Westinghouse Electric was acquired by Northrop before being renamed Northrop Grumman Electronic Systems, which currently supports the E-3's radar.

Variants

 * EC-137D: Two prototype AWACS aircraft with JT3D engines, one fitted with a Westinghouse Electric radar and the other 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. One additional aircraft retained by Boeing for testing, 18 built for NATO with TF33 engines and five for Saudi Arabia with CFM56 engines.
 * KE-3A: These are not AWACS aircraft but CFM56 powered tankers based on the E-3 design. Eight were sold to Saudi Arabia.
 * E-3B: E-3As with improvements, 24 conversions.
 * E-3C: 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 Royal Air Force to E-3C standard with CFM56 engines and British modifications designated Sentry AEW.1, twelve built.
 * E-3F: Production aircraft for the French Air Force to E-3C standard with CFM56 engines and French modifications, four built.
 * E-3G: USAF Block 40/45 modification.

Users

 * France
 * Armée de l'Air x 10
 * Iran
 * Imperial Iranian Air Force x 0 - ten ordered, order cancelled due to Iranian Revolution
 * NATO x 18
 * Saudi Arabia
 * Royal Saudi Air Force x 5
 * United Kingdom
 * Royal Air Force x 12
 * United States
 * United States Air Force x 42