This dissertation presents the AMC method, a new approach in active vibration control for large, flexible transport airplanes. The term AMC abbreviates Advanced Mode Control. AMC basically is the full approximation of eigenstructure assignment or modal synthesis by a minimum-order dynamic feedback. In contrast to the classic modal synthesis design process, AMC does not require the inversion of the modal matrix of the plant, solving one of the major problems of eigenstructure assignment, the non-applicability to high-order systems due to numerical limitations. Another, general limitation of classic state-feedback controllers is the required knowledge of the entire physical state vector of the plant. In the AMC concept, the information originally provided by the physical state vector is made available by a minimumorder dynamic output-feedback, so that the system does not require a state observer and can be realized with a single sensor.All controller parameters are based on physical plant quantities and on the design requirements, so that the system is directly adaptable during operation for best tuning to the current operating point. Furthermore, the physical parameterization allows to derive the controller parameters directly from identified plant quantities, so that a numerical model is actually not necessary for the controller synthesis.