The General Dynamics F-111 Aardvark was a medium-range interdictor and tactical strike aircraft developed in the 1960s that could also perform strategic bombing, reconnaissance, and electronic warfare missions. It pioneered technologies like variable-sweep wings and terrain-following radar for low-level flight. Though it suffered development problems and some roles like carrier-based interceptor failed, the F-111 entered service with the US Air Force in 1967 and Royal Australian Air Force in 1973. It had a crew of two, variable wing sweep from 16 to 72.5 degrees, and an internal weapons bay that could carry bombs or missiles to deliver ordnance on targets.