The overall objective with this thesis is to evaluate a method for designing nonlinear controllers for aircraft with concern in robustness against modeling uncertainties and also to minimize the design effort. The later objective is of great importance since there exists, in the industry, an ambition to automate the design as far as possible. The nonlinear method, State Dependent Riccati Equation (SDRE), used in this thesis is a nonlinear version of classic LQ design and both are evaluated and compared for a few flying conditions. Also another nonlinear control method, Two Timescale Separation (TSS), is tested. LQ and SDRE show equal performance during both looping and more complicated maneuvers, such as high angle of attack velocity-vector roll. Further it is possible to automatize the LQ design as well as it is possible for SDRE. Still SDRE is preferable since it will always be somewhat more accurate than LQ. A comparison with the nonlinear method TSS shows results in favor of LQ/SDRE mostly due to relatively slow dynamics and bad accuracy of TSS. A Monte Carlo simulation is made on LQ and SDRE showing that these controllers are robust against a relatively large modeling error of 40%.