You may be talking about the E-3 Sentry is an airborne warning and control system, or AWACS, aircraft with an integrated command and control battle management, or C2BM, surveillance, target detection, and tracking platform.
The E-3 Sentry is a modified Boeing 707/320 commercial airframe with a rotating radar dome. The dome is 30 feet (9.1 meters) in diameter, six feet (1.8 meters) thick, and is held 11 feet (3.33 meters) 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, or 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.
The United States has maintained an edge over rivals in regards to procuring and maintaining effective aircraft fleets - from fixed-wing to rotary-wing and operator-less drones in between. Within these designs are even sub-variants charged with special mission roles.
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