 The USAF F-111A and Navy F-111B variants used the same airframe structural components and TF30-P-1 turbofan engines. They featured side-by-side crew seating in an escape capsule, as required by the Navy. Because of conflict between the Air Force and Navy over whose requirements had precedence, McNamara intervened in 1961, declaring that the Air Force desires would override suggestions by the Navy. The F-111A variant first flew on 21 December 1964 from Carswell AFB, Texas. It was followed by the F-111B, which first flew on 18 May 1965.
