Method for assisting the formation flight of aircraft, the method being implemented by a system in the form of electronic circuitry on board an aircraft acting as a follower aircraft, the method comprising the following steps: - acquiring information relating to a leader aircraft generating a wake vortex inducing an upward airflow, which the system intends the follower aircraft to benefit from; - determining an effect of the wake vortex experienced by the follower aircraft as a difference between measurements, taken by sensors of the follower aircraft, and modelling of the follower aircraft in a wake vortex-free environment; - determining an estimated position of the wake vortex from the acquired information relating to the leader aircraft and from a wake vortex model, and determining an estimation uncertainty around the estimated position of the wake vortex from the determined effect of the wake vortex experienced by the follower aircraft; and - determining trajectories comprising: a first trajectory, intended to be followed by the follower aircraft, as a trajectory for approaching and tracking the wake vortex, so as to seek to benefit from the upward flow induced by the wake vortex, while remaining outside a potential discomfort window defined by the estimation uncertainty around the estimated position of the wake vortex; characterized by determining trajectories also comprising: a second trajectory corresponding to a phantom aircraft as if the follower aircraft is permanently in an optimal position relative to the wake vortex, namely a placement of the follower aircraft at a predefined distance from the estimated position of the wake vortex when allowed by the dimensions of the potential discomfort window, and otherwise at a predefined margin from the potential discomfort window; and by the method also comprising the following steps: - assessing future overshoots of the phantom aircraft relative to manoeuvring capabilities of the follower aircraft and to passenger comfort rules, with respect to the second trajectory; and - possibly modifying the first trajectory to be followed by the follower aircraft as a function of the assessed overshoots. - acquiring information relating to a leader aircraft generating a wake vortex inducing an upward airflow, which the system intends the follower aircraft to benefit from; - determining an effect of the wake vortex experienced by the follower aircraft as a difference between measurements, taken by sensors of the follower aircraft, and modelling of the follower aircraft in a wake vortex-free environment; - determining an estimated position of the wake vortex from the acquired information relating to the leader aircraft and from a wake vortex model, and determining an estimation uncertainty around the estimated position of the wake vortex from the determined effect of the wake vortex experienced by the follower aircraft; and - determining trajectories comprising: a first trajectory, intended to be followed by the follower aircraft, as a trajectory for approaching and tracking the wake vortex, so as to seek to benefit from the upward flow induced by the wake vortex, while remaining outside a potential discomfort window defined by the estimation uncertainty around the estimated position of the wake vortex; characterized by determining trajectories also comprising: a second trajectory corresponding to a phantom aircraft as if the follower aircraft is permanently in an optimal position relative to the wake vortex, namely a placement of the follower aircraft at a predefined distance from the estimated position of the wake vortex when allowed by the dimensions of the potential discomfort window, and otherwise at a predefined margin from the potential discomfort window; and by the method also comprising the following steps: - assessing future overshoots of the phantom aircraft relative to manoeuvring capabilities of the follower aircraft and to passenger comfort rules, with respect to the second trajectory; and - possibly modifying the first trajectory to be followed by the follower aircraft as a function of the assessed overshoots. a first trajectory, intended to be followed by the follower aircraft, as a trajectory for approaching and tracking the wake vortex, so as to seek to benefit from the upward flow induced by the wake vortex, while remaining outside a potential discomfort window defined by the estimation uncertainty around the estimated position of the wake vortex; characterized by determining trajectories also comprising: a second trajectory corresponding to a phantom aircraft as if the follower aircraft is permanently in an optimal position relative to the wake vortex, namely a placement of the follower aircraft at a predefined distance from the estimated position of the wake vortex when allowed by the dimensions of the potential discomfort window, and otherwise at a predefined margin from the potential discomfort window; and by the method also comprising the following steps: - assessing future overshoots of the phantom aircraft relative to manoeuvring capabilities of the follower aircraft and to passenger comfort rules, with respect to the second trajectory; and - possibly modifying the first trajectory to be followed by the follower aircraft as a function of the assessed overshoots. - assessing future overshoots of the phantom aircraft relative to manoeuvring capabilities of the follower aircraft and to passenger comfort rules, with respect to the second trajectory; and - possibly modifying the first trajectory to be followed by the follower aircraft as a function of the assessed overshoots.