A method for managing avionic data between a flight management system FMS and one or more clients, the FMS comprising resources accessible through avionic services Ci (1,n); the execution of the Ci (1,n) determining an avionic functionality Fj (1,m); each of the Fj (1,m) associated with an intrusiveness parameter Ik and a criticality parameter Ck; the method comprises the steps of receiving a request specifying the call to an Fj (1,m); and determining a predefined execution right for a Ci (1,n), dependent on the predefined intrusiveness and/or criticality parameters associated with the Fj (1,m). Developments describe particularly the comparison of the execution rights, notice of a rejection, various avionic services and functionalities, the management of criticality ranges, consideration of the flight context, etc. Software and system aspects are described (e.g. equipment of EFB type).