Which type of door design allows pressure sealing during flight?

• A. Sliding door
• B. Plug-type door
• C. Hinged door
• D. Bi-fold door

Answer: (B)

The plug-type door is designed to create a pressure seal during flight, making it a critical component for maintaining cabin pressure in an aircraft. This door operates by fitting into a frame in such a way that, as the aircraft climbs to altitude and the internal cabin pressure rises, the door is pushed more tightly into its frame. This ensures that air cannot escape, preserving the pressure that is essential for passenger comfort and safety.

In contrast, sliding doors, hinged doors, and bi-fold doors may not provide the same level of pressure sealing capability as a plug-type door because they do not utilize the same design principle that enhances the sealing effect when under pressure. For example, sliding doors can have gaps that might allow air to leak, and traditional hinged doors may not create the optimal seal under different pressure conditions. The unique functionality of plug-type doors is why they are specifically incorporated in commercial aircraft designs to facilitate safe and efficient operation at high altitudes.