A locking device having a door catch system for helicopter doors, which are embodied as sliding doors, which are to be additionally moved (flush-fitted) into the closed position at right angles to the plane of the door opening in response to their closing movement, consisting of a catch (15a), which is associated with the latch (13) and which is in active connected therewith, by which catch (15a) the sliding door is “caught” directly in front of its locked position in response to a manual closing process until the sliding door has been transferred into its final closed position via the latch (13).