The Pathway to Heaven; Passengers Boarding Bridge

A passenger boarding bridge (PBB) is a moveable, enclosed link that connects an airport terminal gate to airplane passengers can board and disembark without having to step outdoors and risk being open to external conditions.  
It was created by Frank Der Yuen, an American aeronautical engineer, who envisioned a system for loading and unloading passengers and freight. The prototype, the ‘Aero-Gangplank,’ was commissioned for United Airlines.
It’s also known as a jet bridge, a jet walk, an air gate, an air bridge, a sky bridge, and an air tube.

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Before the introduction of jet bridges, passengers would generally board an aircraft by going along a ground-level ramp and climbing a set of movable stairs, or airstairs on aircraft that were equipped with such stairs. Many airports across the world, particularly smaller airports and terminals serving low-cost carriers, use mobile staircases or “ramp stairs.”

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Design and use

Jet bridges are available in a variety of configurations. It may be fixed or moveable, swinging radially and/or expanding in length, depending on building design, sill heights, fueling stations, and operational requirements. Jet bridges have long been a staple of the contemporary airport terminal, providing passengers and crew with a quick, safe walk in and out of a jet.

The fixed (nose loader) allows for a small sweep, or the standard (apron drive) allows for a broader sweep; the multi-door bridge, connects the terminal to numerous aircraft doors through separate walkways, such as those used to service an Airbus A380. Then there’s the bridge that moves between terminal floors for boarding and deboarding, which is less popular.

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A380 Qantas
Credit: batsf.files.wordpress.com

They are made up of a hydraulic or electromechanical elevation mechanism, glass or steel tunnels, and a telescopic extension that can be increased or decreased.

The bridge is connected to a gate in the terminal wall behind the gate desk at the airport terminal. Passengers hand their boarding credentials to the gate attendant, who allows them to pass through once airplane boarding begins.

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They are frequently permanently attached to the terminal building at one end by a pivot and can swing left or right. To accommodate airplanes of various sizes, the cabin at the end of the loading bridge can be lifted or lowered, extended or retracted, and pivoted. An operator’s station in the cab controls these motions. The cab has an accordion-style canopy that allows the bridge to dock with aircraft of various shapes while also providing a nearly weather-proof seal.

Inside, the bridge appears to be a narrow, well-lit corridor with no doors. The majority of loading bridges lack windows, but glass walls are becoming more popular. The walls are usually painted in soothing colors in conformity with airline requirements. Advertisements can be found on the interior or external walls of some bridges.

Credit to: skybrary.aero
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Loading bridges can retract and expand to varying lengths by using a retractable tunnel design. Fixed walkways are used by some airports to effectively extend the span of a loading bridge. The loading bridge rotunda is connected to the fixed walkway that stretches out from the terminal building.

Older systems’ controls had a huge number of discrete motor control buttons, requiring a high level of operator expertise and experience to operate efficiently. With only a few buttons, a graphic display panel, and a single multi-axis joystick, modern control consoles are substantially simpler.

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Electric motors are used to move the passenger bridge. For control, they require power and data lines. The individual pieces do not move at a rapid pace. The cables must, however, be safeguarded from harm. They must withstand wind and rain because they are normally outside the gangway.

Credit to: airlinegeeks.com
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The bridge of the modern jet

A rotunda is a transition point on the façade of the terminal that is found on most jet bridges. On multi-door bridges, this dome-like structure supports the bridge’s telescoping tunnels and separates passengers into different paths. The drive column, which consists of a wheeled bogie that steers or advances the bridge, also supports the tunnels at the far end. The airplane can land at the end of the tunnel, which is known as the cabin. It has a waterproof folding canopy that extends to sit on the airframe. From the apron, a service stair runs up to the cabin

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Advantages

  • Passengers’ safety and comfort: Passengers will not be exposed to the safety dangers that exist in a congested ramp area. Vehicle traffic, moving aircraft, prop wash, jet blast, temperature, and weather extremes are all factors to consider. PBBs are enclosed and occasionally heated or cooled.
  • Secure: By requiring passengers to go from the airport terminal to the plane, they have been allowed temporary access to a restricted section of the airport. As a result, employing PBB will lessen the security threats that passengers would face if they had to go on the plane.
  •  Easy accessibility: PBB is deemed considerably easier for the elderly, handicapped, or persons who require ground handling equipment such as lift trucks to support wheelchair access.
  •  Reduce Labor Necessity: The necessity for ramp monitoring during passenger boarding and deplaning is no longer required. Passengers’ boarding permits are checked as they enter the PBB, and then they proceed directly to the aircraft.
  • Speedier process: In theory, this allows for faster disembarking of larger aircraft, although it is extremely common, especially on Boeing 747s and Boeing 777s, to use one bridge for only passengers in first and/or business class, and the second bridge for those in economy class. The second jet bridge might even extend over the aircraft wing, supported by an overhead structure in some configurations. Most wide-body gates at Amsterdam Airport Schiphol, for example, were initially designed in this manner. Faster loading can result in lower airport fees, fewer delays, and more passengers passing through the airport, all of which have an impact on an airline’s bottom line.
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Disadvantages

  •  Aircraft parking is limited to areas immediately near the terminal due to loading bridges. As a result, airports have mobile staircases to make disembarking at hardstands easier.
  • If managed incorrectly, loading bridges might represent a threat to airplanes. If the bridge is not entirely retracted before departure, it may collide with projecting sections of the taxiing plane, necessitating repairs and delays. Furthermore, the loading bridge may become frozen to the airplane during cold weather. When the jet bridge retracts in this circumstance, it may cause damage to the aircraft if the area has not been adequately de-iced.
  • Damage to the fuselage: the PBB is designed to come into contact with the aircraft at the boarding entrance. Failure of the proximity switch, insufficient operator training, or poor operator technique can all result in the PBB striking the aircraft with more force than planned. This can result in dents, punctures to the skin, or structural damage to the aircraft.
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  •  Door Damage As the weight of the aircraft varies during loading and offloading, the landing gear struts will expand or compress. Most, but not all, PBBs are designed to self-adjust as the aircraft travels to maintain the proper relative height. The bottom of the outward opening aircraft door may come into touch with the PBB floor if the auto-level mechanism fails or the bridge operator fails to make human adjustments as necessary.
  • Terminal Design: PPBs are only permitted to be deployed in parking lots next to the terminal structure. To use them entirely, terminals must have lengthy “fingers” with ramp regions between them, or many terminal buildings must be employed. While older terminal designs can be adapted to include PBBs, the necessity for remote stands, buses, and boarding steps is likely to persist.
  • Expensive: Because airports usually charge higher costs for using loading bridges on stands rather than mobile staircases, low-cost airlines like Ryanair avoid them whenever possible. Also, a single jet bridge unit may cost between 0.5 and 1 million dollars in the United States.
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Sources

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