The Lockheed S-3 Viking is a four seat jet aircraft that was used by the United States Navy to identify, track, and destroy enemy submarines. In the late 1990s, the S-3B's mission focus shifted to surface warfare and aerial refueling. The Viking also provided electronic warfare and surface surveillance capabilities to the carrier battle group. A carrier-based, subsonic, all-weather, multi-mission aircraft with long range, it carried automated weapon systems, and was capable of extended missions with in-flight refueling. Because of the engines’ low-pitched sound, it was nicknamed the "Hoover" after the vacuum cleaner brand.
The S-3 was retired from front-line fleet service aboard aircraft carriers by the US Navy in January 2009, with its missions being assumed by other platforms such as the P-3C Orion, SH-60 Seahawk, and F/A-18E/F Super Hornet. Several examples continue to be flown by Air Test and Evaluation Squadron THREE ZERO (VX-30) at NAS Point Mugu, California for range clearance and surveillance operations and a single example is operated by the National Aeronautics and Space Administration (NASA) at the NASA Glenn Research Center.