An aircraft device includes a rudder, a control unit that applies a deflection instruction to the rudder, a measuring section that measures a recovery characteristic of aircraft movement in response to the rudder deflection instruction, a recorder that records an applied deflection instruction and a corresponding recovery characteristic, and a servo-control that maintains the recovery characteristic. The control unit receives a recovery instruction for a recovery characteristic, which is identifiable for an aerodynamic effect, and generates the rudder deflection instruction induced by the recovery instruction.