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.
McDonnell Douglas AV-8B Harrier II project in March 1975 owing to decreased defense funding, rising costs, and the RAF's insufficient 60-aircraft requirement. With development costs estimated to be around £180–200 million (1974 British pounds), the United States was unwilling to fund development by itself, and ended the project later that year. Despite the project's termination, the two companies continued to take different paths toward an enhanced Harrier. Hawker Siddeley focused on a new larger wing that could be retrofitted to existing operational aircraft, while McDonnell Douglas independently pursued a less ambitious, though still expensive, project catering to the needs of the US military. Using knowledge