A method for manipulating aircraft flight plan segments is provided. A result of an avionics calculation, such as a flight plan sequencing, is selected from among a plurality of results determined by a plurality of systems executed in parallel and placed in competition, each system communicating to at least part of the other systems conditions to be satisfied by the result of a calculation, the method comprises the steps of a given system from among the plurality of systems shares its own calculation result with at least one other system only if its own calculation result satisfies the conditions received from at least one other system. Developments describe various modalities of negotiation and/or selection of the results, the switch to independent and/or the deactivation of a system, voting and/or weighting mechanisms. Software and system aspects are described.