The PLB, more commonly called Jetbridge, Finger, Jetway, Boarding Bridge Airbridge or just "Bridge" is typically a raised passageway consisting of a fixed portion towards the terminal and a moveable portion that is steered into position over the aircraft door. At gates which serve many widebodies, there are often double ended bridges to allow loading through two doors. Normally there's also a staircase from the ground so that crew, engineers, cleaners and so forth can get up and down.

The PCA system, which we call low-pressure air (as opposed to high pressure air) consists of a refrigeration unit (an air conditioner). This is often attached to the PLB but may also come on a cart. One or more large diameter hoses, normally yellow, duct air from the refrigeration unit to low pressure intakes in the belly that lead to the aircraft's mixer unit. From the mixer unit the air is distributed to the various sections of the aircraft.

Another common service is external electrical power. This is routed by cables from the bridge, from a little pole on the ground or from an external generator cart.
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