APY-2
A second generation of the main search and tracking radar aboard the E-3 Sentry Airborne Warning and Control System (AWACS) aircraft, the AN/APY-2 was improved to track surface as well as airborne targets. It has the ability to track moving surface targets both on land, and over sea. Maritime surveillance radar has the additional problem of separating targets from sea surface movement.
The surface tracking feature also gives it better capability against extremely low-flying targets such as cruise missiles. It can track over 600 targets flying at low altitude, as opposed to 200 plus for the earlier AN/APY-1.
The system is built and maintained by Northrop Grumman, which took over maintenance on the earlier AN/APY-1, originally built by Westinghouse.
While it is the second generation radar for the E-3, it still has a mechanically scanned, moving antenna, rather than the more flexible and reliable, all-solid-state, phased array radars on third-generation AWACS aircraft. It is housed in a distinctive disk-shaped container mounted above the fuselage, looking much as if a flying saucer is in formation with an airliner.