The Westwind was originally designed in the United States by Aero Commander as a development of its twin-propeller namesake aircraft, first flying on 2 January 1963 as the Aero Commander 1121 Jet Commander[1]. It was a conventional business jet arrangement, with two engines mounted in nacelles carried on the rear fuselage. The Jet Commander created a problem, since Rockwell already had an executive jet of its own design, the Sabreliner, and could not keep both in production because of anti-trust laws.