Method for the real time calculation of a planned trajectory, notably of a flight plan, combining a mission, and system for managing such a trajectory

The trajectory coming from a planned trajectory, managed by a system, and from at least one trajectory section sent by a third party system to the system, the method at least comprises: a preliminary step in which a knowledge base is produced comprising the calculation parameters and their field of use for the moving object, several envelopes of parameters being defined within the field of use corresponding to different operational constraints of the moving object; a first step in which the system initializes the planned trajectory according to the parameters of the preliminary step, the calculation parameters of the planned trajectory being contained in one of the envelopes; a second step in which the system receives a trajectory section sent by the third party system in order to be inserted in the planned trajectory by replacing a part of the trajectory; a third step in which the received and accepted section is simplified by segmentation in such a way that its calculation parameters are contained in the at least one of the envelopes; the system carrying out calculations on the basis of the simplified trajectory.