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
Harrier Jump Jet of the upgraded "Sea Harrier FA2"; this version entered operational service on 2 April 1993. The Sea Harrier was also procured by the Indian Navy, the first Indian Sea Harriers were entered squadron service during December 1983. As early as 1973, Hawker Siddeley and American aviation manufacturer McDonnell Douglas were jointly working on development of a more capable version of the Harrier. Early efforts concentrated on the development of an improved Pegasus engine, designated the "Pegasus 15", which was being tested by Bristol Siddeley. During August 1981, the program received a boost when British Aerospace (BAe) and McDonnell Douglas signed