Hawker Siddeley Harrier the AV-8C configuration; this programme involved the installation of ECM equipment and adding a new inertial navigation system to the aircraft's avionics. Substantial changes were the Lift Improvement Devices, to increase VTOL performance; at the same time several airframe components were restored or replaced to extend the life of the aircraft. Spain's Harriers, designated AV-8S or VA.1 Matador for the single-seater and TAV-8S or VAE.1 for the two-seater, were almost identical to USMC Harriers differing only in the radios fitted. The Royal Navy's Fleet Air Arm (FAA) operated a substantially modified variant of the Harrier, the British Aerospace Sea Harrier.
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