Standardized distance minima for longitudinal separation is ensured during flight of a second aircraft behind a first aircraft on take-off or landing of the aircraft on one runway or on two parallel runways located near to each other, or during flight one behind the other at near altitude levels in conditions where there is the risk of turbulence from the vortex wake of the first aircraft possibly being present along the direction of movement of the second aircraft. Continuous monitoring of the level of wake vortex flight safety of the second aircraft is carried out in a buffer zone which surrounds the aircraft and is selected on the basis of the direction of the aircraft outside the standardized distance minimum, taking into account pilot reaction time and the time for the system for controlling the second aircraft to respond to a command to change speed.