The present invention concerns a sliding door, which, for example, can be guided on three rollers on the door side in rails on the aircraft structure. Locking of such a cargo door occurs by movement of the cargo door parallel to the aircraft X-axis with the locking pins in corresponding sleeves situated on the aircraft structure. In order to guarantee this, the door opening must be larger than the door itself. The gap produced by this is now closed by means of a locking element that clamps the door. This permits a light structure of the cargo door and therefore a weight saving.