An aircraft control system operates during landing to suppress normal modes of flexing of the aircraft or modes of rigid rotation. The excitation of the modes are measured using accelerometers attached to the aircraft or strain-measuring devices attached to the landing gears. To suppress the modes, the controller operates the flight control surfaces, e.g., elevators, ailerons, rudders and spoilers and/or the steering angle of the nose wheel. This reduces vibration, which reduces wear and makes braking more even because the variation in load on the ground wheels caused by the excitation of the modes is reduced.