The need to ensure effective protection of the Soviet airspace in areas lacking adequate cover by ground radars led the nation's aircraft designers to start working on airborne early warning systems. The Tupolev OKB was the first among the nation's aircraft design bureaus to create an 'eye in the sky', evolving the Tu-126 AEW aircraft from the Tu-114 long-haul turboprop airliner. The aircraft entered service in 1961, filling an important role with the Soviet Air Force 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 eventually never materialized) and the Kamov Ka-31 shipboard AEW helicopter. Due mention is also made of projects that never got off the drawing board the Tu-156, IL-150 and Yakovlev Yak-44.