A family of aircraft originally intended to be able to meet both U.S. Air Force and U.S. Navy needs, the F-111 aircraft was strongly pushed, based on cost-effectiveness criteria, by Robert McNamara. The Air Force wanted a fighter-bomber, while the Navy wanted a long-range interceptor; the missions were simply too different for the 1970s technology to build into one aircraft.
After initial problems, the Air Force F-111F and later versions eventually became effective, more as a light to medium bomber than a fighter-bomber, and, in the EF-111 version, an electronic warfare aircraft. The Navy's F-111B always was overweight for carrier use, and the planned mission was eventually given to the Navy-only F-14 Tomcat. F-111 aircraft were also used by the Royal Australian Air Force.
The F-111 did have many advanced features. Some, such as a variable geometry "swing wing", were in vogue for a time, and used on the F-14 as well as the Soviet MiG-23 and the U.S. B-1 Lancer bomber. More advanced control systems, however, have obviated the need for variable geometry wings in high-speed aircraft. Rather than ejection seats, the crew were ejected in a capsule; the nose could tilt downward, giving the aircraft its informal name of Aardvark or 'vark. If it was ever assigned a formal "nickname", such as the Tomcat or Phantom, the name never was used.
It was the first operational aircraft to have a purpose-built terrain-following radar, allowing it to make extremely low altitude attacks in all weather. In Air Force service, its approximate replacement was the F-15E Strike Eagle.