Hawker Siddeley Harrier single lever added in the cockpit. For horizontal flight, the nozzles are directed rearwards by shifting the lever to the forward position; for short or vertical takeoffs and landings, the lever is pulled back to point the nozzles downwards. The Harrier has two control elements not found in conventional fixed-wing aircraft: the thrust vector and the reaction control system. The thrust vector refers to the slant of the four engine nozzles and can be set between 0° (horizontal, pointing directly backwards) and 98° (pointing down and slightly forwards). The 90° vector is normally deployed for VTOL manoeuvring. The reaction control
Hawker Siddeley Harrier overcome efforts to obstruct its procurement. The AV-8A entered service with the Marine Corps in 1971, replacing other aircraft in the Marines' attack squadrons. The service became interested in performing ship-borne operations with the Harrier. Admiral Elmo Zumwalt promoted the concept of a Sea Control Ship, a 15,000-ton light carrier equipped with Harriers and helicopters, to supplement the larger aircraft carriers of the US Navy. An amphibious assault ship, , was converted into the "Interim Sea Control Ship" and operated as such between 1971 and 1973 with the purpose of studying the limits and possible obstacles for operating such a