Abstract : The flight control problem is one of regulation and control of a nonlinear, highly uncertain multiple input-output system, to achieve desired performance bounds. Feedback control theory has not been able to cope with even its approximate linear time-invariant version, because of its neglect of synthesis techniques in which uncertainty and performance bounds appear quantitatively. However, there have been two recent breakthroughs, giving precise, rigorous, quantitative synthesis techniques for both linear and nonlinear time-varying, single and multiple input-output systems containing plants with large uncertainties. In these techniques, quantitative performance bounds can be assigned in the time and/or frequency domain. For a large problem class, it is guaranteed that the design satisfies the specifications over the entire range of plant uncertainty. One of the breakthroughs was applied to a significantly nonlinear model of the short-period, longitudinal flight control problem. Uncertainty was included in the model by allowing for a large range in velocity and air-density, without any provision for their measurement. The output c*(t), was to lie within specified bounds in response to a range of step commands. The design was simulated with excellent results. (Author)