The invention relates to a method to assist in the landing of an airplane (1) in its final flight phase, following a current approach path (6) toward a runway (2), comprising the determination, at a given flight point, of a landing delay margin, called MRAmax, corresponding to an estimated delay during which the braking actions must be undertaken, after the wheels touch down, to enable the airplane (1) to stop on the runway (2).The invention also relates to a device (10) which comprises means (20) of acquiring parameters necessary to the method, computation means (30) which determine a landing delay margin MRAmax from the information received from said means (20) and means (40) of presenting the information to alert the crew, said landing delay margin MRAmax being established according to the method.