1. A method for managing the flight of a first aircraft (A 1 ) using a flight management system flying along a trajectory and being subject to a temporal constraint defined by a date determined with respect to a fixed point be by a temporal separation with respect to a second aeroplane (A 2 ), the first aircraft (A 1 ) flying according to a constant air speed (V a1 ), with an initial wind (Ve), the method comprising the following steps: calculation of a distance (ΔD) on the basis of the initial wind (Ve) and of the air speed (V a1 ) using the flight management system; and modification of the trajectory using the flight management system: if the distance (ΔD) is positive, lengthening the trajectory by a distance equal to the distance (ΔD); if the distance (ΔD)is negative, shortening the trajectory by a distance equal to the opposite of the distance (ΔD), the trajectory being situated in an air route and comprising flight segments and at least one transition between the flight segments, the modification of the trajectory making it possible to satisfy the temporal constraint without modifying the air speed of the first aircraft (A 1 ), the modification of the trajectory comprising the following steps: choosing of a transition of the trajectory, calculation of a roll directive (PhiNom 2 ) for the transition on a basis of the a temporal discrepancy (ΔT), calculation of a radius of curvature (R 2 ) of the trajectory in the transition on the basis of the roll directive (PhiNom 2 ), if the radius of curvature (R 2 ) is less than a minimum radius (R 2lim ) making it possible to remain in the air route, the roll directive (PhiNom 2 ) is applied to the aircraft, otherwise: calculation of a maximum time discrepancy (ΔT max ) in the transition and of a corresponding roll directive, calculation of a remaining time discrepancy (ΔT remaining ): ΔT remaining =ΔT −ΔT max , and iteration of the step of choosing a transition with a remaining temporal discrepancy (ΔT remaining ) until there is no longer any transition, not yet selected.