VHF omnidirectional range
Very High Frequency Omnidirectional Range Station (VOR) is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine its position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons. It uses frequencies in the very high frequency (VHF) band from 108.00 to 117.95 MHz. Developed in the United States beginning in 1937 and deployed by 1946, VOR became the standard air navigational system in the world, used by both commercial and general aviation, until supplanted by satellite navigation systems such as GPS in the early 21st century. As such, VOR stations are being gradually decommissioned. In 2000 there were about 3,000 VOR stations operating around the world, including 1,033 in the US, but by 2013 the number in the US had been reduced to 967. The United States is decommissioning approximately half of its VOR stations and other legacy navigation aids as part of a move to performance-based navigation, while still retaining a "Minimum Operational Network" of VOR stations as a backup to GPS. In 2015, the UK planned to reduce the number of stations from 44 to 19 by 2020.
DVOR (Doppler VOR) ground station, collocated with DME.
MCT VOR, Manchester Airport, United Kingdom.
D-VORTAC TGO (TANGO) Germany
VORTAC located on Upper Table Rock in Jackson County, Oregon
Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination.
Amelia Earhart's Lockheed Electra had a prominent RDF loop on the cockpit roof.
The Orfordness Beacon as it appears today.
VOR transmitter station
Cessna 182 with GPS-based "glass cockpit" avionics