Abstract: The longitudinal feedback coefficients of a stability augmentation system （SAS） for a sample aircraft were selected in the light of the condition that the normal acceleration response at the pilot's position approximated to zero. With the aid of references [2] and [3] the improvement in riding qualities of the airfrarne/SAS system due to the selected coefficients were evaluated. The dynamic characteristics of the airframe/SAS system were also analyzed.The results demonstrate that the riding qualities are desirable when the control anticipative parameter of the airframe/SAS, system approaches to 9.81/lx, and the operating range of the SAS is limited to the elevator displacement less than 10% of the max.displacement.It is necessary to take into account the lift due to the elevator deflection in the analysis of the dynamic characteristics of the airframe/SAS system, if the tail area is large enough in comparison with the wing area such as 0.2.