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 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 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). <EOS>