空桥或称登机桥是一种设备在飞机场的设施，连接登机门至飞机舱门，方便乘客进出机舱。

在空桥问世之前，乘客必须步行与地面同高的柏油路上，再爬上移动式登机梯，此种登机方法仍在世界多数机场使用，但通常都是只能容纳小型飞机的小型机场（机型多半比波音737或空中巴士A320小而矮）；部分的老旧航站楼由于规模较小而无法设立多座空桥，除了少数改建而追加的空桥外，也会搭配摆渡巴士将乘客载运至停靠在空桥范围外的飞机上以供乘客登机，如香港启德机场、**松山机场等等。美国的首座空桥在1959年7月于旧金山国际机场搭建。

A jet bridge (also termed jetway, gangway, aerobridge/airbridge, air jetty, portal, skybridge 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 or being exposed to the elements. 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.