An investigation is presented into the computation of rotating stall in an industrial gas turbine compressor using a hybrid whole annulus and single passage computational domain. The objective of this investigation is to demonstrate the use of large-scale unsteady computations with quicker turn-around times in the design cycle to develop and evaluate several variable guide vane schedules and/or bleed settings. This means that subsequent engine test campaign could be carried out with significantly lower test matrix size in terms of the number of variable guide vane schedules and/or the handling bleed settings thus reducing the overall development time and cost. Rotating stall that was measured and characterised during a previous compressor rig test (Krishnababu, et al. ) were successfully predicted by large-scale unsteady computations using TurboStream. The predicted number of stall cells and their speed agreed closely with the test data. The methodology validated was applied to predict and mitigate the rotating stall in the development of a compressor for a new gas turbine engine. Using this approach, it was possible to define bleed control system that ensured stall free operation.