File Description: The Advanced Tactical Fighter Standoff! Take a flight test of the world's most advanced prototypes with this single download. You will get both the YF-22A "Lightning" and the YF-23A "Black Widow II". In 1981, the Air Force developed a requirement for an Advanced Tactical Fighter (ATF)as a new air superiority fighter. It would take advantage of the new technologies in fighter design on the horizon including composite materials, lightweight alloys, advanced flight control systems, higher power propulsion systems, and stealth technology. The Lockheed-Boeing-General Dynamics team built two YF-22 prototypes, while the Northrop and McDonnell Douglas team built two YF-23 prototypes. These models for X-Plane 6.21 were updated from the 5.66 versions.