A mission management system to manage both ground and flight phases of a mission of an aircraft is proposed. The mission management system may be implemented in flight management system architecture with core and supplementary modules distinct from each other. The core module may implement a set of generic functionalities related to a flight management of the aircraft, and the supplementary module may implement supplementary functionalities specific to an entity to which the aircraft belongs. The mission management system may include a flight management unit to define and manage a flight plan and associated flight trajectory, an airport navigation unit to define and manage a ground plan and associated ground trajectory, and a mission management unit to manage a continuity between the ground and flight phases of the mission and prediction computations made by the flight management and the airport navigation units.