The Lockheed S-3 Vikings are carrier-based aircraft designed for the specific purpose of anti-submarine warfare. They replaced the Grumman S-2 Trackers during the 1970s. The first flight of a Viking occurred in 1972 and operations began in 1974. The last S-3A was delivered in 1978 and most have been upgraded to 'B' models which featured Harpoon air-to-surface missile capability.
