A jet bridge (also termed jetway, jetwalk, airgate, gangway, aerobridge/airbridge, skybridge, airtube, or its official industry name passenger boarding bridge (PBB)) is an enclosed, movable connector which most commonly extends from an airport terminal gate to an airplane, and in some instances from a port to a boat or ship, allowing passengers to board and disembark without going outside and being exposed to harsh weather. Depending on building design, sill heights, fueling positions, and operational requirements, a jet bridge may be fixed or movable, swinging radially, and/or extending in length. The jetway was invented by Frank Der Yuen.
Similar devices are used for astronauts to enter spacecraft, which are installed in the appropriate height of the launch tower.
Jet bridges provide all-weather dry access to aircraft and enhance the security of terminal operations. They are often permanently attached at one end by a pivot (or rotunda) to the terminal building and have the ability to swing left or right. The cabin, at the end of the loading bridge, may be raised or lowered, extended or retracted, and may pivot, to accommodate aircraft of different sizes. These motions are controlled by an operator's station in the cab. The cab is provided with an accordion-like canopy, which allows the bridge to dock with aircraft with differing shapes, and provide a nearly weather-proof seal. Additionally, many models offer leveling devices for the portion of the floor that makes contact with the aircraft; this allows passengers to slowly transition from level aircraft floor to sloping jet bridge floor. As such, jet bridges provide enhanced access to aircraft for passengers with many types of disabilities and mobility impairments, as they may board and disembark without climbing stairs or using a specialized wheelchair lift.
Some airports with international gates have two or three bridges for larger aircraft with multiple entrances. In theory, this allows for faster disembarking of larger aircraft, though it is quite common, especially on aircraft such as Boeing 747s and Boeing 777s, to use one bridge for only passengers in first class and/or business class, while the other bridge is for the use of passengers in economy class. The Airbus A380 is unique in that both of its double decks have outside doors; so that two or more loading bridges are possible, a jetbridge for each deck having the advantage being faster aircraft loading (in parallel). Such connectors were constructed at Boston's Logan Airport, Kuala Lumpur International Airport, Hartsfield-Jackson Atlanta International Airport, Johannesburg International Airport and in the new international terminal at Calgary International Airport. Faster loading can lead to lower airport charges, less delays and more passenger throughput for the airport, all factors which impact an airline's bottom line.
Though loading bridges are usually permanently attached at their terminal-building end, leaving only the cab free to move, this is not always the case. Those at Melbourne Airport's international terminal are — and at Hong Kong's old Kai Tak Airport were — anchored in the middle and movable at either end to permit the terminal building-end to be raised or lowered to connect with either the departures level or the arrivals level of the terminal building.