Hawker Siddeley Harrier AV-8As to the AV-8C configuration—the work focused mainly on extending useful service lives and improving VTOL performance. The AV-8C and the remaining AV-8A Harriers were retired by 1987. These were replaced by the Harrier II, designated as the AV-8B, which was introduced into service in 1985. The performance of the Harrier in USMC service led to calls for the United States Air Force to procure Harrier IIs in addition to the USMC's own plans, but these never resulted in Air Force orders. Since the late 1990s, the AV-8B has been slated to be replaced by the F-35B variant of the
Hawker Siddeley Harrier the more risky isolated approach. The first RAF squadron to be equipped with the Harrier GR.1, No. 1 Squadron, started to convert to the aircraft at RAF Wittering in April 1969. An early demonstration of the Harrier's capabilities was the participation of two aircraft in the "Daily Mail" Transatlantic Air Race in May 1969, flying between St Pancras railway station, London and downtown Manhattan with the use of aerial refuelling. The Harrier completed the journey in 6 hours 11 minutes. Two Harrier squadrons were established in 1970 at the RAF's air base in Wildenrath to be part of its air