A processing station for registering a piece of passenger's luggage for a trip, wherein the processing station comprises: an injector for receiving the piece of luggage associated with the passenger; at least one sensor associated with the injector, the at least one sensor, in combination with at least the floor of the injector, creating a zone around the piece of luggage; and a controller associated with the sensor being adapted to: monitor, via the at least one sensor, intrusions through the zone to determine one or more of whether a predetermined limit on dimensions of the piece of luggage has been exceeded or whether a foreign object has intruded the zone from outside, and allow further processing of the piece of luggage only if no intrusion of the zone is detected; and wherein the controller adjusts the area of the zone to accommodate different sizes of luggage.