The concept of an aircraft being an integrated weapons system had proliferated, where sensors such as the radar would be more directly tied into navigation and weapons systems. de Havilland included this concept in the design of the Sea Vixen. According to aviation author David Hobbs, it was the first British fighter aircraft to be designed in this manner. In June 1955, a semi-navalised prototype, "XF828", was completed for the purpose of conducting carrier flight deck suitability trials. For this purpose, XF828 featured several changes, including the alteration of the profile of the wing leading edges and the strengthening of the wings, as well as underwing fixture points for catapult launches, and a tailhook for arrested landings; however, the Sea Vixen lacked a wing folding mechanism, or racks for armaments. On 20 June 1955, this aircraft made its first flight from de Havilland's facility at Christchurch Airfield in Dorset. The following year, XF828 performed its first arrested deck landing on the Royal Navy's aircraft carrier . In April 1956, the finalised production drawings were formally issued. The fully navalised production Sea Vixen featured a number of improvements over earlier development models. These included the addition of a powered folding wing system, reinforcement of the landing gear to withstand the additional stresses of carrier landings, a steerable nose wheel, a revised tail unit, and the redesigning of the fuselage to carry armament. On 20 March 1957, the first true Sea Vixen, designated as the "Sea Vixen FAW.20" (fighter all-weather, later redesignated "FAW.1"), performed its first flight. This aircraft was promptly used for clearance trials, in particular for addressing handling problems; the second production aircraft was used for engineering trials and the third aircraft for conducting radar trials. On 2 July 1959, the first Sea Vixen-equipped squadron was formed. Production Sea Vixens were manufactured at first by de Havilland at its former World War II Airspeed Ltd. "shadow factory" at Christchurch near Bournemouth, starting in March 1957. In August 1962, all production was moved to another de Havilland factory located at Hawarden, near Chester. Beyond the initial "FAW.1" model, de Havilland proceeded with the development of an improved variant, which was subsequently designated as the "Sea Vixen FAW.2". This served as the successor to the FAW.1 and included many improvements.