Abstract: A computing system for a flight simulator is formed as a distributed system with a common bus MFB to which five processing modules 11 to 15 are connected. The module 11 processes data relating to aircraft movement and receives data from a pilot's manual controls simulator 16, and supplies data to a motion output unit 17 and a visual field output unit 18. the module 12 processes data relating to engine performance. The module 13 processes data relating to navigation and communciations, and the module 14 processes data relating to aircraft equipment systems such as hydraulic and electrical systems. The modules 12, 13 and 14 may each supply control signals to instruments read by a trainee pilot, and each receive signals from manually operable members or switches operated by the trainee pilot. The module 15 is an instructor station and communicates with a VDU terminal 21.