VOR - VHF Omnidirectional Radio

Developed in the US deployed in 1946, VOR is the standard air navigational system in the world, used by both commercial and general aviation. There are about 3000 VOR stations around the world.

VOR is a type of short-range radio navigation system for aircraft, enabling aircraft to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons, with a receiver unit. It uses radio frequencies in the very high frequency (VHF) band from 108 to 117.95 MHz.

A VOR ground station sends out a master signal, and a highly directional second signal that varies in phase 30 times a second compared to the master. This signal is timed so that the phase varies as the secondary antenna spins, such that when the antenna is 90 degrees from north, the signal is 90 degrees out of phase of the master. By comparing the phase of the secondary signal to the master, the angle (bearing) to the station can be determined.

This bearing is then displayed in the cockpit of the aircraft, and can be used to take a fix as in earlier radio direction finding (RDF) systems, although it is, in theory, easier to use and more accurate. This line of position is called the "radial" from the VOR. The intersection of two radials from different VOR stations on a chart provides the position of the aircraft.

VOR stations are fairly short range, the signals have a range of about 200 miles.

Updated On: 12.02.19