A method and device for monitoring and controlling a path of a following aircraft (AC2) with respect to vortices (V1, V2) generated by a leading aircraft (AC1) while both aircraft (AC1, AC2) fly in a formation (F), wherein the device includes a unit for determining, using a vortex transport model, a safety position (PS) at which the following aircraft (AC2) is not subjected to effects of the vortices (V1, V2) generated by the leading aircraft (AC1), a unit for determining, using a vortex signature model, an optimum position (PO) at which the following aircraft (AC2) benefits from at least one (V1) of the vortices (V1, V2), and a control unit for bringing and keeping the following aircraft (AC2) in the safety position (PS) while a predetermined condition(s) is met and otherwise for bringing the following aircraft (AC2) and keeping it in the optimum position (PO).