Plug doors use air pressure differentials to remain closed, rather than the strength of the locking mechanism as found in standard types of doors. This kind of door is commonly used in aircraft with pressurized cabins, where the air pressure is greater on the interior of the cabin. Higher air pressure forces the plug door into its wedge-shaped socket. To open the door while the cabin is pressurized, operators must use a plug door latch handle, which may be detachable depending on the aircraft. Plug doors are also used in submarine vessels and spacecraft, which also encounter extreme pressure differentials during operation.
