 The Sukhoi bureau concentrated on adaptations of the standard "Su-27UB" tandem-seat trainer.However, the Soviet Air Force favoured the crew station (side-by-side seating) approach used in the Su-24 as it worked better for the high workload and potentially long endurance strike roles.Therefore, the conceptual naval side-by-side seated trainer was used as the basis for development of the "Su-27IB" (Russian for "Istrebityel Bombardirovshchik" - "Fighter Bomber") as an Su-24 replacement in 1983.