A derivative of the Il-76 transport, the A-50 "Mainstay" has become the primary Russian AWAC aircraft since its introduction in 1984. With its dorsally-mounted, rotating radome, the Mainstay resembles other AWAC aircraft, such as the American E-3C Sentry, although its performance is generally inferior. In their battle management role, AWACS aircraft are a central component of a coordinated air defense, and as such, are a high value target.%n