From Canadian Power Wiki
The Beriev A-50 (NATO reporting name: Mainstay) is a Soviet airborne early warning and control (AEW) aircraft based on the Ilyushin Il-76 transport. The existence of the A-50 was revealed in 1980 by Adolf Tolkachev. Developed to replace the Tupolev Tu-126 "Moss", the A-50 first flew in 1978. It entered service in 1984, with about 40 produced by 1992.