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.
British Aerospace Harrier II service. The decision to retire was controversial as there was no immediate fixed-wing replacement in its role or fixed-wing carrier-capable aircraft left in service; in the long term the Harrier II is to be replaced by the Lockheed Martin F-35 Lightning II. Development of a much more powerful successor to the Harrier began in 1973 as a cooperative effort between McDonnell Douglas (MDD) in the US and Hawker Siddeley (in 1977, its aviation interests were nationalised to form part of British Aerospace) in the UK. First-generation Harriers were being introduced into Royal Air Force and United States Marine Corps; operational