The Antonov An-71 (NATO reporting name: Madcap) was a SovietAWACS aircraft intended for use with VVS FA (Fighter Bomber) forces of the Soviet Air Force. Its design was based on An-72, with a completely redesigned rear fuselage supporting the rotodome of the radar atop the broad chord forward swept fin. The cargo hold held the electronic equipment and six operators stations. Development never progressed past the prototype stage, the first of which flew on 12 July 1985. The program was canceled, with the fall of the Soviet Union when issues with the RADAR [Vega-M Kvant] could not be resolved. In 2010, one example was transferred to Ukraine State Aviation Museum for restoration and display.
Prior to the fall of the Soviet Union the Air Force was divided into three aircraft based groups of units. They were the VVS-DA (Voenno-Vozdushnye Sily Dal'naya Aviatsiya) or Long Range Aviation (Bombers), VVS-FA (Voenno-Vozdushnye Sily Frontovaya Aviatsiya) (Fighters, Fighter Bombers and Attack aircraft) and the VVS-VTA (Voenno-Vozdushnye Sily Voenno-Transportnaya Aviatsiya) or Military Transport aircraft. The PVO (Voyska protivovozdushnoy oborony or Voyska PVO) which was the primary defensive fighter, Interceptor and surface based defensive force was in no way part of the VVS. This means the A-50 Mainstay AWACS aircraft and its predecessor the Tu-126 Moss both served exclusively with the Voyska PVO and did not assist in the direction of day to day tactical aircraft. The An-71 was designed to be used overland to support the FA. This doctrine of each force having its own AWACS plane is contrary to most Western air forces use of land based AWACS aircraft. This doctrine difference lead in part to the fallacy that the An-71 was designed to be used by on the Russia Aircraft Carriers.
It should be noted that the An-71 Madcap is often cited as a carrier based AWACS aircraft. In short it was not as is already described above under AWACS doctrine. However a highly modified design, the An-75, was proposed for use on the Soviet Aircraft Carriers under construction but the AVMF (Soviet Naval Aviation) canceled its development when it was realized that too much of a re-design would be needed to make the An-75 safe to operate off of any of the proposed aircraft carriers. The AVMF or Aviatsiya Voenno-Morskogo Flota (Literally Aviation for the Military Maritime Fleet,) decided to seek a second purpose built AWACS proposal using an improved Kvant-M version of the existing An-71/An-75's Kvant Radar by the Vega-M design bureau. The An-75, if built would have had engines mounted under the wing rather than above, similar to the later An-74TK-300, and had many other structural and aerodynamic changes. In the end the An-75 would have only shared a slight commonality with the An-71/An-72 aircraft families and was deemed to costly to continue in-light of the clean sheet design the Yak-44E.