A gate in aviation is a long, movable, "bridge" that allows passengers to embark and disembark their aircraft.
- Jetway bridges
- Air stairs, either built into the aircraft or from a mobile vehicle
- Mobile lounges
- Leaving the aircraft via mobile safety steps and walking across the apron into or from the terminal building
For most gates in US or Canadian domestic airports, the door opens to a single level jetway which leads to the aircraft door. For international airports, certain gates must be configured to accept arriving international passengers. The configuration varies from airport to airport but usually, the door leading to the gate is moved further into the terminal, and will open to a room, where the passengers will pass through on their way to the aircraft. Inside the room will be an escalator leading to customs and immigration on a different level. When the gate is being used for departures or domestic arrivals, the door leading to the waiting area will be opened and usually the escalators will be blocked off, thus passengers will not mistakenly wander into customs and immigration. For an international arrival, the door leading to the waiting area is simply closed, and passengers are directed to the escalators for immigration/customs.
The general rule in the US and Canada for international flights is that any gate may host a departing international aircraft, but only internationally configured gates may host international arriving aircraft. This makes for some problems in some airports like O'Hare International Airport where the two major tenants, United Airlines and American Airlines, are forced to use Terminal 5 for international arrivals, and then tow their planes back to their own terminals for subsequent flights, causing valuable gate space at Terminal 5 to be used up.
Before the era of the jet bridge or jetway, airline passengers embarked onto the aircraft from ground level. If initially indoors, passengers would exit the waiting area through a door to the outside and then, a short distance from the door, there would typically be a chain link fence with an actual fence gate that was opened to permit passengers to then proceed to the aircraft and climb up the air-stair to enter.
- 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>.