A gate, or gatehouse, is an area of an airport that provides a waiting area for passengers before boarding their flight. While the exact specifications vary from airport to airport and country to country, most gates consist of seating, a counter, an aircraft entry/exit doorway, and a jet bridge.
Domestic vs international
At most gates a single doorway opens to a jet bridge which leads to the aircraft door. For airports that handle international flights, certain gates must be configured to accept arriving international passengers. The configuration varies from airport to airport, but typically the door is configured similar to a sallyport, except the central vestibule opens to a hallway leading to a customs hall. When the gate is being used for departures or domestic arrivals, the door leading to the waiting area will be opened and the hallway to customs will be blocked off, preventing passengers from entering into the customs hall. For international arrivals not coming from cities with preclearance, the door leading to the waiting area is closed and passengers are directed to the customs hall.
Jet bridge vs airstair
Before the era of the jet bridge, or jetway, airline passengers embarked onto the aircraft from ground level via airstairs. If initially indoors, passengers would exit the waiting area through a door to the outside and then passengers would proceed to the airstairs leading to the aircraft door.
- Freudenrich, Craig, Ph.D. "How Airports Work." HowStuffWorks. N.p., n.d. Web. 24 Nov. 2012. <http://science.howstuffworks.com/transport/flight/modern/airport3.htm>.