A distinguishing feature of aerospace applications is the large envelope of operation in which the process is usually highly nonlinear and has different characteristics from one operating condition to another. Therefore, the objective of the present work is to design an autopilot that can cope with modeling errors, plant parameters variations, external disturbances and unmodeled dynamics, besides providing good performance and high stability. To achieve this objective, an adequate nonlinear mathematical model representing the dynamical behavior of the missile was derived (previous work) from which the linearized model for the underlying missile is obtained. A robust flight control system or autopilot is designed, for precise tracking, using (1) classical control design technique (previous work) and (2) Mixed sensitivity IL control design technique, the contribution of this paper. The paper presents, briefly, different issues in robust control highlighting the robustness to different sources of uncertainty for the purpose of achieving good tracking and disturbance rejection, and preserving the system internal stability. Then it summarized some of the controller design techniques including classical and advanced methods such as mixed sensitivity H n . Then, the structure of the underlying missile control system with the performance requirements imposed on it is developed. Finally, the design trials and analysis of the flight control system are carried out using the above techniques with the objective to satisfy the performance requirements including good tracking and disturbance rejection in presence of =nodded dynamics. The H has good robustness compared to
the classical. However, the 1-1,0 controller has higher order. Therefore, this technique needs to be investigated more with the system, giving more attention to the weight selection and its order, the crucial point in its design.