The Beriev A-50 'Mainstay' was the Soviet Union's principal AEW aircraft, much in the same line as the US E-3. Structurally, it is a lengthened modification of the Il-76 airframe fitted out by Beriev with a large rotating saucer radome mounted one the fuselage. This radome is capable of locating and tracking aircraft in 360 degrees over land and water and vector up to 12 interceptions simultaneously. However, the A-50 is not with a wide range of structural problems which greatly decrease its effectiveness compared to the E-3. Due to the weight of the equipment on board, the A-50 is unable to take off with a full fuel load, restricting its range. On top of this, airborne refueling is extremely complicated due to the buffeting caused by the radome in a tanker's slipstream. The A-50 also lacks a crew resting area and other accommodations making crew fatigue a severe problem. In spite of this the A-50 will continue being Russia's major AEW and will likely continue to be developed if only because of the lack of a suitable alternative. A-50s have been sold or lent to China, India, and Iraq and were used near this Middle-Eastern nation during the Gulf War to track Allied air operations.

Originally designated Il-76VKP, the maiden flight of the 'Mainstay' was during 1980. It entered service four years later as the A-50 and was improved as the A-50U with a new and more powerful radar. In Iraqi service, a similar AEW conversion is known as the Adnan-1 and is equipped with a French SDA-G radar. The Chinese version is known as the A-50I and was originally intended to carry the advanced Israeli IAI Phalcon AESA radar.