VHF Omnidirectional Range - VOR (Beacon)[PDF]
The VOR is the basic short-range aid used to provide navigation guidance along airways, air traffic services (ATS) routes, intermediate and final approach tracks, and specified tracks.
Bearing information may be used by aircraft to fly toward or away from the VOR station at any azimuth selected by the pilot or to know the relative position of the aircraft from the VOR station.
The 180° ambiguity in this indication is resolved by the provision of a “to/from” of the VOR indicator in the aircraft avionics.
Ground equipment: VOR
Two types of VOR beacons are used:
- Terminal VOR (T-VOR): they are used in the terminal area of airports and cover a relatively small geographic area protected from interference by other stations on the same frequency. T-VOR output power is 50 W which allows covering a region from 1000 ft AGL up to and including 12000 ft AGL at radial distances out to 25 NM. The allocated band ranges from 108 to 111.850 MHz with the 100 kHz digit being always even (example: 108.25MHz, 109 MHz)
- En route VOR: they are used as route fixes within high or low airspace. Their output power is 200 W which provides a range up to 200 NM. The allocated band ranges from 112 to 117.950 MHz
VOR performance limitations
The equation of line-of-sight distance (without obstacles):
Example: for 3000ft, D= 65NM; for 9000ft, D=115NM.
Nevertheless, the VOR receiver becomes incapable of radial detection inside this cone. The VOR receiver will display the OFF flag and the radial indicator should be at maximum deviation.
- at 20000ft, D = 20/2 = 10 NM
- at 4000ft, D = 4/2 = 2NM
VOR accuracy and interference
The radial line is read in degrees of azimuth from the magnetic North and is technically accurate to within ±2°. The over-all system accuracy is ±5°.
Principles of VOR signals
The VOR beacon simultaneously transmits two signals:
- A constant omnidirectional signal (30Hz) called the reference phase
- A directional signal (30Hz) which rotates through 360°, during a 0.03 second system cycle (30Hz), and consistently varies in phase through each rotation.
The two signals are only exactly in phase once during each rotation – when the directional signal is aligned to the magnetic north.
VOR on charts
VOR only symbol
These are some examples of the VOR symbol on charts:
The representation using a circle is the Jeppesen representation. The representation using a hexagon can be found on some local charts published by national organizations. Some representations can mix the two symbols.
Example: VOR LCA 112.1MHz “LA CHATRE”
These are some examples of the VOR/DME symbol on charts:
These are some examples of the VORTAC symbol on charts:
Below, these are the TACAN only symbols. Do not confuse them with others!
- VID 150259 - Creation
- VID 450012 - Update
DATE OF SUBMISSION
- 09:22, 11 June 2021
- This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.
- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.