The Boeing E-3 Sentry is an Airborne Warning and Control System (AWACS). These aircraft are based on the 707-320B commercial airliner platform and were introduced into operation in 1977. 68 units were produced between 1977 and 1992. The aircraft are still in service today and are an important part of military operations. The Air Force expects to operate the platform until 2035, when the Boeing E-7A Wedgetail will replace it.