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 and were inducted the same year. Ten more Sea Harriers were purchased in November 1985; eventually a total of 30 Harriers were procured, 25 for operational use and the remainder as dual-seat trainer aircraft. Until the 1990s, significant portions of pilot training was carried out in Britain due to limited aircraft availability. The introduction of the Sea Harrier allowed for the retirement of India's previous carrier fighter aircraft, the Hawker Sea Hawk, as well as for the Navy's aircraft carrier, INS "Vikrant" (ex-HMS "Hercules"), to be extensively modernised between 1987 and 1989. India has operated Sea Harriers from both the