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
Hawker Siddeley P.1127 after the P.1154's selection over the Dassault Mirage IIIV. Following the termination of the P.1154, the RAF then began studying a straightforward upgrade of the Kestrel as a production aircraft; accordingly, it issued Requirement ASR 384, which sought a V/STOL ground attack jet, known as the "P.1127 (RAF)". In late 1965, the RAF placed an order for six pre-production P.1127 (RAF) aircraft. On 31 August 1966, the first of these P.1127 (RAF) aircraft made its maiden flight. In early 1967, an order for 60 production aircraft was formally received by Hawker Aviation; at this time the aircraft received the "Harrier