A missile which is highly maneuverable is perhaps one of the most challenging of all guidance and control issues. The complexity further increases if we consider coupled motion of the vehicle. An Aerodynamic Vehicle will demonstrate a dynamic coupling between pitch, yaw and roll. These couplings may be inertial, kinematical or aero-dynamical. Depending upon the aerodynamic and inertia coefficients which results from the shape and the mass distribution, these couplings can be destabilizing. Effects of these various types of couplings on the stability and robustness of the vehicle are studied in this paper and some suggestions are made to avoid instability of the autopilot. Results of simulations are provided to verify the comments.