Abstract: A flying control system for aircraft in which a control circuit comprising a cable and quadrant pulley arrangement is arrange to effect pivotal displacement of a control surface in response to pilot's control demand, the control circuit including system disengagement means whereby if one of the cables is broken or becomes disconnected, the disengagement means will effectively isolate the control surface or pilot's control demand input means from adverse residual control forces arising as a result of the cable break or disconnect. By this arrangement the secondary or standby control system is isolated from adverse control limitations which may arise as a consequence of cable severance in , for example, the primary control device.