A protection device including a unit for implementing a protection function that prevents the aircraft from flying under a given height with respect to the ground. The device includes a unit for determining the current values of parameters, and at least the current position of the aircraft and a current heading deviation of the aircraft with respect to a landing strip. A calculation unit is provided for calculating, during a landing on the landing strip, from data including said current values, a current longitudinal distance defined in the horizontal plane and necessary for bringing the aircraft into a position for deactivating the protection function. A checking unit is provided for checking whether a condition dependent on the current longitudinal distance is met, the protection function being automatically deactivated if the checking unit concludes that this condition is met.