Abstract: The invention concerns a device (1) comprising first means (3) for determining a threshold value depending at least on one low altitude flight path, which is followed by an aircraft, as well as on navigation errors, for guiding and calculating the flight path, second means (4) for measuring the current real height of the aircraft above the overflown ground during a low altitude flight along the flight path, third means (5) for comparing said current real height to the threshold value, and fourth means (8) for emitting a warning signal, if the current real height drops to or below the threshold value, as well as optionally fifth means (10) for controlling the aircraft so as to increase its altitude and bring it to a secure altitude, when the current real height drops below or to the threshold value.