the invention relates to a guiding device for part of a jet engine nacelle that can move in translation , comprising : a rail fixedly mounted on part of the nacelle , and a slide which is connected to the mobile part and which can slide along the rail . the invention is characterised in that the guiding device is provided with a built - in retractable system for preventing the translational movement of the slide , for which purpose the device includes : at least one blocking means mounted such that it can move on the rail and occupy alternatively an engaged position in which it forms a translational abutment for the slide and a released position in which it is moved away from the slide and enables the relative translational movement of the slide beyond the locking system , and at least one means for controlling the blocking means .