The invention relates to methods and devices for aircraft's safe operation and is embodied in the form of a method and system for informing a user, for example an aircraft crew and/or a flight controller, on the probable penetration of the aircraft into dangerous areas of the vortex shedding of vortex generators which are located near the aircraft at a forecast time when the aircraft passes through a simulated control plane situated at a preventive distance in the direction of motion of the aircraft, said distance being calculated on a basis of a sufficient forecast period so that the aircraft carries out a flight evasive manoeuvre. The preventive system defines the trajectory and intensity of the vortex shedding of the vortex generators, the co-ordinates of intersecting points of the vortex sheddings with a control plane, the geometric parameters of the dangerous areas thereof (26, 27) according to danger criteria specified by a user, forms a warning area (28) in said control plane, an area of the forecast positions of the aircraft (25) and dangerous vortex shedding areas (26, 27) at a forecast time, follows up the events of crossing the warning area (28) and/or the area of the aircraft forecast positions (25) associated with the dangerous vortex shedding areas (26, 27) and draws attention of the user to said event with the aid of display devices (16, 17) and a visualisation device (18).