Method of graphical representation, modification and validation of an aeronautical flight plan for an aircraft avionics system, said system comprising means for computing and generating said flight plan, a system for managing the tasks necessary for the accomplishment of said flight plan, a visualization device displaying a graphical representation of said flight plan and a man-machine interface able to carry out selections, modifications or additions in the information contained in said graphical representation, said selections, modifications and additions being taken into account by the task management system, said graphical representation comprising a timeline on which feature at least the various phases of the flight plan and the information corresponding to said phases, wherein the method comprises a step of displaying at least one first interactive graphical icon, representative of the overall state of progress of the tasks to be performed before a change of flight phase.