ABSTRACT:   Applying automation control methods to flexible aircrafts such as High Speed Civil Transport (HSCT) is a way to overcome the difficulties of the coupling between the elastic modes and the rigid body modes. The difficulties involved by sensing the flexure motion and the rigid body motion, which is a source of additional dipoles near the imaginary axis of the s-plan, make the choice of a suitable automatic control method a challenge. To this purpose, this paper intends to investigate the applicability of control strategies, which would be able to compensate the difficulties in stabilizing the aircraft. The proposed method is the so-called Generalized Predictive Control (GPC) technique. After a brief overview of HSCT modeling we recall the basic principles of the GPC. Then, we are interested in the application of this method with four different choices of the tuning parameters. In our study, the objective is not only to stabilize the pitch rate step response, but also to have this response accepted from point of view flying quality by controlling the elevator deflection.