Alternative piloting system for integrating in a pre-existing aircraft

A pre-existing aircraft including an original systems comprising a flight control system, an autopilot system, and an alternative piloting system, wherein the alternative piloting system comprises:

• a piloting device independent of the original systems, comprising a positioning unit arranged to produce positioning data relating to the aircraft, and a control unit arranged to produce an alternative piloting setpoint for the pre-existing aircraft;
• an acquisition and analysis device, comprising acquisition means arranged to acquire data produced by the original systems and also the positioning data and the alternative piloting setpoint as produced by the piloting device, and decision means arranged to decide whether the alternative piloting setpoint should or should not be used for piloting the pre-existing aircraft;
• and
• an interface device arranged to control the flight control system of the aircraft on the basis of the alternative piloting setpoint when the decision means of the acquisition and analysis device decide that said alternative piloting setpoint should be used for piloting the pre-existing aircraft.