The E-3 Sentry is an airborne warning and control system (AWACS) aircraft  with an integrated command and control battle management, surveillance, target detection, and tracking platform.  The aircraft provides an accurate, real-time picture of the battlespace to the Joint Air Operations Center. AWACS provides situational awareness of friendly, neutral and hostile activity, command and control of an area of responsibility, battle management of theater forces, and early warning of enemy actions during joint, allied, and coalition operations.

The airframe is a modified Boeing 707 with a rotating radar dome. The dome is 30 feet in diameter, six feet thick, and is held 11 feet above the fuselage by two struts. It contains a radar subsystem that permits surveillance from the Earth's surface up into the stratosphere, over land or water. The radar has a range of more than 250 miles (375.5 kilometers). The radar combined with an identification friend or foe, (IFF), subsystem can look down to detect, identify and track enemy and friendly low-flying aircraft by eliminating ground clutter returns that confuse other radar systems.

During the Summer of 1965, the USAF asked for proposals for feasibility studies into the provision of an Airborne Early Warning and Control system to replace the Air Force's existing EC-121's. Contracts were given to Boeing, Douglas and Lockheed, with Lockheed being eliminated in July 1966, and Douglas in July 1970.

Engineering, test and evaluation began on the first E-3 Sentry in October 1975. The first flight (with full mission avionics) was 25 May 1976. In March 1977 the 552nd Airborne Warning and Control Wing (now 552nd Air Control Wing, Tinker Air Force Base, Okla.), received the first E-3s.

A total of 68 E-3s were produced before production ended in 1992. Operators include: United States Air Force, NATO, Royal Air Force, Royal Saudi Air Force and the French Air Force.