The Sikorsky UH-60 Black Hawk is a medium-lift utility or assault helicopter derived from the twin-turboshaft engine, single rotor Sikorsky S-70. The YUH-60A (S-70) was the winner of the United States Army Utility Tactical Transport Aircraft System (UTTAS) competition in the early 1970s to replace the UH-1 Huey family. It would go on to serve as the basis for variants in service with other branches of the US military.