The Soviet Union needed to ensure effective protection of its airspace in order to maintain its security. For those areas lacking adequate cover by ground radars, airborne early warning systems were developed. Known by the acronym, AWACS, which stands for Airborne Warning And Control System, the Soviets set to work on filling this apparent gap in their defences briefing the nation's leading aircraft designers to start working on appropriate systems. The Tupolev OKB was the first among the Soviet aircraft design bureaux to create an "eye in the sky". The aircraft produced was known as the Tu-126 AEW. This was a development of the Tu-114 long-haul turboprop airliner. The aircraft, entered service in 1961, filling an important role with the Soviet Air Force. It remained in service until replaced in the early 1980s by the Ilyushin/Beriyev A-50 AWACS based on the IL-76MD transport. In addition to these two types, the book describes the highly unorthodox Antonov An-71 with its tail-mounted rotodome (intended for operations from a large aircraft carrier which in the end was never built) and the Kamov Ka-31 shipboard AEW helicopter. Due mention is also made of projects that never got off the drawing board such as the Tu-156, L-150 and Yakovlev Yak-44.