The US Air Force's E-3 Sentry Airborne Warning and Control System (AWACS) aircraft is continuing to provide superior command-and-control capabilities after four decades of service.

The Sentry is designed to provide situational awareness of friendly, neutral and hostile activity; command and control of an area of responsibility; battle management of theatre forces; all-altitude and all-weather surveillance of the battle space and early warning of enemy actions.

The first E-3 -- a modified Boeing 707/320 commercial airframe with a rotating radar dome -- entered US Air Force service in 1977, according to manufacturer Boeing.

The radar dome, which is 30 feet (9.1 metres) in diameter and six feet (1.8 metres) thick, is held 11 feet (3.33 metres) above the fuselage by two struts.

The radar held inside the dome enables surveillance from the Earth's surface up into the stratosphere, over land or over water and has a range of more than 250 miles (375.5km).

Combined with computer subsystems on the E-3 Sentry, it can gather broad and detailed battlefield information, including the position and tracking information on both friendly and enemy aircraft and ships, according to the US Air Force.

That information can then be sent to major command-and-control centres in rear areas or aboard ships, or even to the president and secretary of defence.

The E-3 can also provide direct information needed for air superiority, interdiction, reconnaissance, airlift and close-air support for friendly ground forces.

The E-3 Sentry has proven through experience that it can respond quickly and effectively to a crisis and support worldwide military operations, according to the Air Force.

Since it was first adopted, the E-3 fleet has undergone extensive enhancements, including upgrades to radar, computing, satellite communications and air traffic management.

By 1994, 68 E-3 Sentry aircraft were in service worldwide with the United States, NATO, Saudi Arabia, France and the United Kingdom.

E-7A

The US Air Force is planning to replace the E-3 fleet with the E-7A.

The Air Force in February awarded Boeing a $1.2 billion contract to begin work on the E-7 fleet, with plans for 26 aircraft by 2032, Defense News reported.

Australia, Turkey and South Korea already use E-7s, and production is under way for a British fleet.

The E-7 utilises a multirole electronically scanned array long-range sensor that allows operators to fix its gaze on a single or multiple targets.

The Air Force plans to first buy two rapid prototype E-7s, with the first to be fielded in 2027. It will then make a decision on the remainder of the fleet in 2025.