At the time it was realized that the Grumman S-2 Tracker anti-submarine aircraft would not be able to absolve its missions effectively anymore, a design competition was started in 1967 to create a capable replacement. The result was a turbofan-powered anti-submarine aircraft by Lockheed. In comparison to the S-2, the S-3 was able to patrol an area being three times larger than the S-2 was able to patrol and the S-3 was able to carry twice the armament. The 461 million dollar contract, requiring six test aircraft and three mock-ups, was launched on 1st August 1969.