The benefit of a Passenger Boarding Bridge, also referred to as a PBB, Jetway, or Sky Bridge, is that it allows passengers to deplane from an aircraft quickly and easily right to the terminal. This is a safer and more efficient method than using stairs or ramps that bring passengers to the apron where they may have to walk or be bussed to another part of the airport terminal. In this article, Aviation & Mechanical Expert Chad Phillips details PBBs as a complex piece of machinery that if not maintained and operated properly, could lead to dangerous conditions.
PASSENGER BOARDING BRIDGES – EXPERT ARTICLE
Jetways can be adjusted to service several different sizes and types of aircraft, allowing the aircraft gate to be used for more than one type of jet liner. However flexible the Passenger Boarding Bridge is, it does have limitations and will not service all planes, most notably smaller aircraft with narrower doors. In these cases, a Mobile Bridge Adapter (MBA) is used to “bridge” the gap. The PBB is brought to within a few feet of the plane door and the Bridge Adapter is slid into place, allowing a walkway from the smaller aircraft to the jetway.
Bridge Adapters are not integral to the PBB, and are attached to the PBB with nothing but straps, clips, and gravity. Improper storage, care, and maintenance of the Bridge Adapters may lead to degraded material and slippery surfaces. It is the responsibility of the company owning these pieces of equipment to inspect, and take out of service, any bridge adapter that creates an unsafe condition. Ramp agents must properly and completely install the bridge adapters to allow for a safe method for passengers to disembark aircraft.
PBB Operation & Positioning
The PBB is driven to the parked airplane by an operator. It is the operator’s responsibility to ensure that the PBB does not contact the aircraft in a way that will damage the airframe. They must also ensure that the walkway of the PBB cab is positioned at the aircraft door to eliminate any trip or fall hazards to pedestrians. If the operator does not position the jetway close enough to the plane, the distance from the door would create a gap between the PBB and aircraft, and if the operator places the floor of the PBB too far below the aircraft door, this then creates a step down from the floor of the aircraft to the sky bridge floor.
The position of the PBB cab in relation to the aircraft is critical since there are no handrails available to passengers, and the first few feet of the jetway floor that come into contact with the airplane may be open to the weather. Snow, ice, and rain may lead to a very slippery surface on an unmaintained sky bridge walkway.
Hydraulic Leveling Systems
As a ship floating at port will rise and fall with the tides and weight of its cargo, a plane too floats, not on water, but on its hydraulic landing gear struts. As the weight of passengers and cargo change, the aircraft struts will extend making it taller as weight decreases, or as weight increases will compress the struts making the plane shorter. The Passenger Boarding Bridge has an automatic leveling system to automatically adjust for these changes in height. Once the PBB operator properly positions the bridge, they engage the auto-leveling system and the bridge will rise and fall with the ever changing position of the aircraft. This maintains that aforementioned vertical distance that passengers and crew depend on for safe boarding and deplaning.
If these systems fail, alarms should sound, and if not monitored can lead to aircraft damage or excessive distances between the aircraft and bridge creating a fall hazard. Ramp Agents should cease passenger loading or unloading if the distance between the aircraft and passenger boarding bridge creates a hazard that will injure passengers. This includes excessive vertical distance, or a large gap between the passenger boarding bridge and the plane.
Ground Crew Safety
Workers on the ground need to be very cautious around Passenger Boarding Bridges. These behemoth machines are moved by an almost silent set of drive motors that propel a set of very large wheels and tires. Most PBBs are now equipped with bumper bars, as well as warning lights and alarms. In the high noise environment of an airport ramp, however, the alarm may not always be noticed. The area in which the PBB moves within the aircraft stand (parking space) is outlined by pavement markings and is designated as a No Parking Area for equipment and a warning area for ground personnel. Operators need to ensure that areas where they plan to move the bridge are clear of personnel and ground support equipment.
Applicable Standards for PBBs
For more information on the Passenger Boarding Bridge, the FAA published Advisory Circular 150/5220-21C which contains performance standards, specifications, and recommendations for equipment used in the boarding of airline passengers. Additional standards also exist that specifically address Passenger Boarding Bridges.
Robson Forensic offers in-house technical experts to address all safety aspects relevant to the boarding and deplaning of aircraft. Our aviation mechanics can assess failures and malfunctions to equipment and machinery in and around aircraft, while our tenured flight attendants and ground operations experts can address whether safety protocols and other processes were followed leading up to an event.
For more information, contact the author of this article or submit an inquiry.
Aviation & Mechanical Expert
Chad Phillips is an Aviation and Mechanical expert with over 15 years of professional experience inspecting, maintaining, and repairing helicopters, airport equipment, and a broad range of industrial machinery/equipment. As a helicopter and aviation mechanic, Chad has extensive hands-on experience and training in hydraulic systems, flight controls, driveline, avionics, electrical and other complex systems, equipment, and tools. Chad earned certification as an airframe and powerplant (A&P) mechanic for the Sikorsky Aircraft Corporation. In that role, he traveled to locations worldwide to troubleshoot, repair, and provide technical expertise and training on complex hydraulic, electrical, and mechanical systems for customer operations.