Abstract: The invention relates to the simulation of an aircraft's flight controls and particularly the mechanical reactions produced on the pilot's controls.The reaction force is produced by a servo-controlled, hydraulic actuator whose piston moves a distance X which is proportional to the deflection of the pilot's control. A servo signal, whose amplitude is proportional to the component of the reaction force depending on the displacement X, is obtained by digital calculation, filtering and analogue multiplication.The invention can be applied to flight training systems and to artificial feel systems (AFS).