Hawker Siddeley Harrier as VTOL and STOL manoeuvres (where the traditional lift and control surfaces are useless) requiring skills and technical knowledge usually associated with helicopters. Most services demand great aptitude and extensive training for Harrier pilots, as well as experience in piloting both types of aircraft. Trainee pilots are often drawn from highly experienced and skilled helicopter pilots. In addition to normal flight controls, the Harrier has a lever for controlling the direction of the four vectoring nozzles. It is viewed by senior RAF officers as a significant design success, that to enable and control the aircraft's vertical flight required only a
British Aerospace Sea Harrier in 1973, and are now popularly recognised as aircraft carriers. Almost immediately upon their construction, a ski-jump was added to the end of the 170-metre deck, enabling the carriers to effectively operate a small number of V/STOL jets. The Royal Air Force's Hawker Siddeley Harrier GR1s had entered service in April 1969. A navalised variant of the Harrier was developed by Hawker Siddeley to serve on the upcoming ships; this became the Sea Harrier. In 1975, the Royal Navy ordered 24 Sea Harrier "FRS.1" (standing for 'Fighter, Reconnaissance, Strike') aircraft, the first of which entered service in 1978. During this