is being towed by means of a tow bar hitched to a steerable bottom portion of the undercarriage the method including the step of generating an alarm when a towing force imposed by the tow bar on the undercarriage reaches or exceeds a predetermined force threshold the threshold is caused to vary as a function of an orientation of the steerable bottom portion of the undercarriage application_number US 201113582667 A description with reference to fig1 an aircraft nosewheel undercarriage 1 comprises a strut 2 connected directly to the structure of the aircraft and having a rod 3 mounted to slide telescopically therein so as to co operate with the strut 2 to form a shock absorber the rod 3 carries an axle 4 at its bottom end with two wheels 5 mounted thereon the strut 2 has a steering member comprising a collar 6 rotatably mounted about the strut 2 in this example the undercarriage presents a castor angle u03b1 that is substantially equal to 10 u00b0 when not in a towing situation the collar 6 is operated by steering actuators the collar is connected to the rod 3 by a steering scissors linkage 7 having two branches that are hinged together in such a manner that the angular position of the rod 3 is determined by the angular position of the collar 6 in order to steer the wheels 5 it suffices to control the steering actuators so as to turn the collar 6 thereby turning the rod 3 by means of the steering linkage 7 when the aircraft is being towed on the ground.