VOR — VHF Omnidirectional Range

How a VOR Determines Your Position

A VOR (VHF Omnidirectional Range) ground station transmits a signal engineered so that an aircraft's receiver can extract a radial — the magnetic bearing from the station to the aircraft — purely from the shape of the received signal, without needing any two-way communication. In practical terms, a VOR beacon is like a lighthouse that broadcasts "which direction from me you are" in every direction simultaneously, and an aircraft tuned to that frequency reads its own radial directly off the cockpit instrument (traditionally a VOR indicator or, in modern glass cockpits, the same information integrated into the primary navigation display).

VOR Frequency Band and Service Classes

VORs operate in the 108.0 to 117.95 MHz band, a slice of VHF adjacent to (but distinct from) the voice communication band. Not every VOR has the same range: stations are classified by service volume — Terminal (T) class covers roughly 1,000 to 12,000 feet above the station out to 25 nautical miles, Low Altitude (L) class extends coverage up to 18,000 feet and 40 nautical miles, and High Altitude (H) class covers multiple altitude bands up to 45,000 feet with service range out to 130 nautical miles at the highest levels — meaning the reliable range of a given VOR depends on both the aircraft's altitude and which class of station it's using.

VOR's Place in the Airway System

For most of the second half of the twentieth century, VOR stations were the backbone of instrument navigation: conventional airways (often called "Victor airways" in the US, using the V-prefix) were quite literally drawn as straight lines connecting VOR stations, and aircraft navigated by flying directly to, from, or along the radial between them. Airport instrument approach procedures were frequently built around a VOR located on or near the field, giving aircraft a reliable way to align with the runway in poor visibility before satellite navigation existed.

The Decline — and Deliberate Retention — of VOR

Since the rollout of GPS and broader satellite-based Performance-Based Navigation (PBN), most enroute navigation and many approaches no longer rely on VOR at all, and aviation authorities in the US, Europe and elsewhere have been actively decommissioning a portion of their VOR networks to reduce maintenance cost. Rather than eliminating VOR entirely, though, regulators have deliberately kept a reduced "minimum operational network" of VOR stations in place as a backup navigation system — insurance against a GPS outage, jamming, or satellite-system failure, since VOR's ground-based signal is largely immune to the kind of disruption that can affect satellite navigation over a wide area at once.