Abstract: A computer-implemented method for managing the data of an aircraft flight plan comprises collecting initial data of an operational flight plan from a flight planning system FPS by an electronic device of electronic flight bag EFB type; converting the initial data and communicating the converted data to the avionics system of the flight management system FMS, the FMS being able to compute an avionic flight plan on the basis of the converted data; and retrieving the avionic flight plan data such as processed by the flight management system FMS. Developments describe notably the verification of the security and/or of the integrity of the converted initial data by means of predefined compliance rules; the emulation of avionics protocols and the use of the encipherment of the data. System aspects and software aspects are described.