CentralNotice Plug door From Wikipedia, the free encyclopedia Jump to: navigation , search This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (September 2013) Plug door with cross-section A plug door is a door designed to seal itself by taking advantage of pressure difference on its two sides and is typically used on aircraft with cabin pressurization . [ 1 ] The higher pressure on one side forces the wedge-shaped door into its socket, making a good seal and preventing it being opened until the pressure is released. Non-plug doors rely on the strength of the locking mechanism to keep the door shut whereas a plug door relies on the pressure differential to keep it shut. The term "plug door" may also refer to a sliding bus doo...