VHF omnidirectional range

VORDVORVHF omni-directional rangeVOR stationVOR-DMEVORsVORTACnavigationVery High Frequency Omnidirectional RangeVHF omnidirectional radio range (VOR)
Very High Frequency (VHF) Omni-Directional Range (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.wikipedia
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Radio navigation

radionavigation serviceradio navigation aidradionavigation
Very High Frequency (VHF) Omni-Directional Range (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.
As the LF/MF signals used by NDBs can follow the curvature of earth, NDB has a much greater range than VOR which travels only in line of sight.

Radio

radio communicationradio communicationswireless
Each station broadcasts a VHF radio composite signal including the navigation signal, station's identifier and voice, if so equipped.
In radio navigation systems such as GPS and VOR, a mobile receiver receives radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth.

Very high frequency

VHFVHF radioVHF band
Each station broadcasts a VHF radio composite signal including the navigation signal, station's identifier and voice, if so equipped. It uses frequencies in the very high frequency (VHF) band from 108.00 to 117.95 MHz.
Air traffic control communications and air navigation systems (e.g. VOR & ILS) work at distances of 100 km or more to aircraft at cruising altitude.

Hazardous Inflight Weather Advisory Service

At some locations, this voice signal is a continuous recorded broadcast of Hazardous Inflight Weather Advisory Service or HIWAS.
Hazardous Inflight Weather Advisory Service (HIWAS ) is a continuous broadcast of hazardous weather information which is transmitted over selected VORs.

Low-frequency radio range

low frequency radio rangeradio rangeFour-course radio range
They became the major radio navigation system in the 1960s, when they took over from the older radio beacon and four-course (low/medium frequency range) system.
The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main navigation system used by aircraft for instrument flying in the 1930s and 1940s, until the advent of the VHF omnidirectional range (VOR), beginning in the late 1940s.

Non-directional beacon

NDBNDB approachnon-directional beacon (NDB)
Some of the older range stations survived, with the four-course directional features removed, as non-directional low or medium frequency radiobeacons (NDBs).
As the name implies, the signal transmitted does not include directional information, in contrast to other navigational aids such as low frequency radio range, VHF omnidirectional range (VOR) and TACAN.

Visual Aural Radio Range

Developed from earlier Visual Aural Radio Range (VAR) systems, the VOR was designed to provide 360 courses to and from the station, selectable by the pilot.
The VAR bridged the technological gap between the Low-Frequency Radio Range (LFR) radio navigation system and the VHF omnidirectional range (VOR) navigation system.

Victor airways

Victor airwayenroute airway radialVictor 23
A worldwide land-based network of "air highways", known in the US as Victor airways (below 18000 ft) and "jet routes" (at and above 18,000 feet), was set up linking VORs.
They are defined in straight-line segments, each of which is based on a straight line between either two VHF omnidirectional range (VOR) stations, or a VOR and a VOR intersection, hence the beginning letter V (pronounced as Victor, in the ICAO phonetic alphabet).

Morse code

MorseInternational Morse CodeMorse-code
The station's identifier is typically a three-letter string in Morse code.
For example, the VOR-DME based at Vilo Acuña Airport in Cayo Largo del Sur, Cuba is coded as "UCL", and UCL in Morse code is transmitted on its radio frequency.

Course deviation indicator

Omni Bearing Indicatordisplay dial
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 centred on the display.

Distance measuring equipment

DMEDistance Measuring Equipment (DME)Distance measuring equipment (aviation)
This limits VOR (and DME) range to the horizon—or closer if mountains intervene. In many cases, VOR stations have collocated distance measuring equipment (DME) or military Tactical Air Navigation (TACAN) — the latter includes both the DME distance feature and a separate TACAN azimuth feature that provides military pilots data similar to the civilian VOR.
A common combination is a DME colocated with a VOR (VHF Omnidirectional Range) transmitter in a single ground station.

Tactical air navigation system

TACANTactical Air NavigationTAC
In many cases, VOR stations have collocated distance measuring equipment (DME) or military Tactical Air Navigation (TACAN) — the latter includes both the DME distance feature and a separate TACAN azimuth feature that provides military pilots data similar to the civilian VOR.
It is a more accurate version of the VOR/DME system that provides bearing and range information for civil aviation.

Airway (aviation)

flight pathairwayairways
VOR and the older NDB stations were traditionally used as intersections along airways.
Airways are defined with segments within a specific altitude block, corridor width, and between fixed geographic coordinates for satellite navigation systems, or between ground-based radio transmitter navigational aids (navaids; such as VORs or NDBs) or the intersection of specific radials of two navaids.

Area navigation

RNAVArea navigation (RNAV)
This is the basic form of RNAV and allows navigation to points located away from VOR stations.
For land-based operations, the initial systems used very high frequency omnidirectional radio range (VOR) and distance measuring equipment (DME) for estimating position; for oceanic operations, inertial navigation systems (INS) were employed.

VORTAC

A collocated VOR and TACAN beacon is called a VORTAC.
A VORTAC is a radio-based navigational aid for aircraft pilots consisting of a co-located VHF omnidirectional range (VOR) beacon and a tactical air navigation system (TACAN) beacon.

Andrew Alford

alford loops
These are usually Alford Loop antennas (see Andrew Alford).
Born in Samara, Russia, Alford invented and developed antennas for radio navigation systems, now used for VHF omnidirectional range and instrument landing systems.

Horizontal situation indicator

Electronic Horizontal SituationHSI
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 centred on the display.
It combines a heading indicator with a VHF omnidirectional range-instrument landing system (VOR-ILS) display.

Local-area augmentation system

Local Area Augmentation SystemGBAS landing systemLAAS
Future satellite navigation systems, such as the European Union Galileo, and GPS augmentation systems are developing techniques to eventually equal or exceed VOR accuracy.
This lowers initial cost and maintenance per aircraft since only one receiver is required instead of multiple receivers for NDB's, DME, VOR, ILS, MLS and GPS.

Radio direction finder

automatic direction finderdirection finderradio compass
In the 1950s, aviation NDBs were augmented by the VOR system, in which the direction to the beacon can be extracted from the signal itself, hence the distinction with non-directional beacons.

Direction finding

radio direction findingradio direction-findingdirection-finding
The intersection of radials from two different VOR stations can be used to fix the position of the aircraft, as in earlier radio direction finding (RDF) systems.
Starting in the 1950s, these beacons were generally replaced by the VOR system, in which the bearing to the navigational aid is measured from the signal itself; therefore no specialized antenna with moving parts is required.

Instrument flight rules

IFRinstrument flightblind flying
A number of navigational aids are available to pilots, including ground-based systems such as DME/VORs and NDBs as well as the satellite-based GPS/GNSS system.

Instrument landing system

ILSglideslopeglide slope
The first 4 MHz is shared with the instrument landing system (ILS) band.

Wide Area Augmentation System

WAASplus or minus 2 metersWAAS GPS
The FAA started planning to shut down their existing long-distance systems (VOR and NDBs) in favor of GPS.

Aircraft

heavier-than-airheavier-than-air flightheavier-than-air aircraft
Very High Frequency (VHF) Omni-Directional Range (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.