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
McDonnell Douglas AV-8B Harrier II to the Lightning II would save $1 billion. After entering service in the mid-2010s, the F-35B will start to replace the AV-8B in 2016, with the AV-8B expected to continue service until 2025. Meanwhile, the AV-8B will receive revamped defensive measures, updated data-link capability and targeting sensors, and improved missiles and rockets, among other enhancements. The AV-8B Harrier II is a subsonic attack aircraft of metal and composite construction that retains the basic layout of the Hawker Siddeley Harrier, with horizontal stabilizers and shoulder-mounted wings featuring prominent anhedral (downward slope). The aircraft is powered by a single Rolls-Royce Pegasus turbofan