An aircraft mission computing system, comprising: - an aircraft trajectories computing engine during the mission, being able to compute a given trajectory of the aircraft during the mission based on operational mission specifications; - a mission deck comprising a display and a display manager; characterized in that the display manager is able to simultaneously display, on the display, a plurality of respective buttons (114, 116, 118; 182) for defining a plurality of respective operational specifications, each definition button (114, 116, 118; 182) being able to be actuated by a user to define a operational specification of the mission from among a plurality of choices for the respective operational specification; the computing engine being able to be activated after defining a choice of operational specification using each definition button (114, 116, 118; 182) to determine at least one possible trajectory of the aircraft based on each choice of operational specification defined by the user using each definition button (114, 116, 118; 182); the display manager being able to display on the display, after the activation of the computing engine, at least one outcome indicator (122, 124) providing feasibility information of the mission with the mission respecting each choice of operational specification defined by the user using each definition button (114, 116, 118; 182), the outcome indicator being able to present a first display configuration representative of a feasibility of the mission with the mission respecting each operational specification defined by the user using each definition button (114, 116, 118; 182) and at least one second display configuration, representative of a non-feasibility of the mission with the mission respecting each operational specification defined by the user using each definition button (114, 116, 118; 182). - an aircraft trajectories computing engine during the mission, being able to compute a given trajectory of the aircraft during the mission based on operational mission specifications; - a mission deck comprising a display and a display manager; characterized in that the display manager is able to simultaneously display, on the display, a plurality of respective buttons (114, 116, 118; 182) for defining a plurality of respective operational specifications, each definition button (114, 116, 118; 182) being able to be actuated by a user to define a operational specification of the mission from among a plurality of choices for the respective operational specification; the computing engine being able to be activated after defining a choice of operational specification using each definition button (114, 116, 118; 182) to determine at least one possible trajectory of the aircraft based on each choice of operational specification defined by the user using each definition button (114, 116, 118; 182); the display manager being able to display on the display, after the activation of the computing engine, at least one outcome indicator (122, 124) providing feasibility information of the mission with the mission respecting each choice of operational specification defined by the user using each definition button (114, 116, 118; 182), the outcome indicator being able to present a first display configuration representative of a feasibility of the mission with the mission respecting each operational specification defined by the user using each definition button (114, 116, 118; 182) and at least one second display configuration, representative of a non-feasibility of the mission with the mission respecting each operational specification defined by the user using each definition button (114, 116, 118; 182).