Said system (1) comprises as least the following principal functions, a flight path management function (2), a navigation function (3) which makes it possible to calculate the position of the aircraft, a function (5) for calculation of deviations between the position of the aircraft and a flight path to be followed, a management function (6) of at least one navigation database, a management function (7) of performance calculations of the aircraft, and a function (8) of management of interfaces and of display, each of said principal functions being allocated to a specific device of the aircraft, said flight path management function (2) being linked to each of said other principal functions.