This paper proposes a gain scheduled flight controller design method satisfying various design requirements, including gain and phase margins. The problem to satisfy stability margin requirement can be converted to an Integral Quadratic Constraints (IQC) stability condition. This IQC condition can be considered as a kind of mixed sensitivity H_∞ problem with complex constant weights. Linear Matrix Inequality (LMI) theory is used to solve the derived mixed sensitivity problem. The effectiveness of the proposed method is verified by designing a lateral-directional flight controller for the Automatic Landing Flight Experiment (ALFLEX).