A worldwide land-based network of "air highways", known in the US as Victor airways (below 18,000 ft (5,500 m)) and "jetways" (at and above 18,000 feet), was set up linking VORs. An aircraft can follow a specific path from station to station by tuning into the successive stations on the VOR receiver, and then either following the desired course on a Radio Magnetic Indicator, or setting it on a Course Deviation Indicator (CDI) or a Horizontal Situation Indicator (HSI, a more sophisticated version of the VOR indicator) and keeping a course pointer centered on the display.