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Understanding VORs in Aviation: A Pilot’s Guide

In modern aviation, navigation is a blend of tradition and technology. While GPS has become the dominant tool for pilots today, ground-based navigation aids such as the VHF Omnidirectional Range (VOR) remain an essential part of the National Airspace System (NAS). Whether used as a primary reference or a backup, every pilot should understand how VORs work, their types, and how to use them effectively in flight.



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What is a VOR?

A VOR (Very High Frequency Omnidirectional Range) is a ground-based radio navigation system that transmits signals in the VHF frequency band (108.0 – 117.95 MHz). These signals provide azimuth (direction) information to aircraft, enabling pilots to determine their position and navigate accurately from one point to another.


Unlike older navigation aids such as the NDB (Non-Directional Beacon), VORs allow a pilot to fly specific radials (magnetic bearings extending outward from the station), making them far more precise.


How a VOR Works

The VOR system transmits two signals simultaneously:

  1. Reference Phase Signal – sent in all directions.

  2. Variable Phase Signal – rotates 30 times per second, creating a difference in phase depending on the aircraft’s position.


The aircraft’s VOR receiver compares these signals and calculates the aircraft’s bearing (radial) from the VOR station. By tuning into the correct frequency, the pilot can use the Omni-Bearing Selector (OBS) knob on the aircraft’s navigation instrument to select and fly along a chosen radial.


Types of VORs

Not all VORs are the same. The FAA classifies them into three categories:

  1. Terminal VOR (T-VOR)

    • Range: 25 NM

    • Altitude: Surface to 12,000 feet AGL

    • Typically located near airports for terminal area navigation.

  2. Low VOR (L-VOR)

    • Range: 40 NM

    • Altitude: 1,000 to 18,000 feet AGL

    • Commonly used for enroute navigation.

  3. High VOR (H-VOR)

    • Range: 40 NM (up to 14,500 feet), 100 NM (14,500–18,000 feet), 130 NM (18,000–45,000 feet), and 100 NM (45,000–60,000 feet).

    • Ideal for long-range enroute navigation.


VOR/DME and VORTAC

Some VOR stations are paired with additional systems:

  • VOR/DME – Combines azimuth (VOR) with distance measuring equipment (DME), allowing pilots to know both direction and distance from the station.

  • VORTAC – A combined facility with both VOR and TACAN (Tactical Air Navigation, used by the military). Civilian pilots receive VOR and DME signals, while military pilots also receive TACAN.


Using a VOR in the Cockpit

Pilots use a VOR indicator or Horizontal Situation Indicator (HSI) to interpret VOR signals. The main elements include:

  • OBS Knob – Used to select a desired radial.

  • Course Deviation Indicator (CDI) – Shows whether the aircraft is left or right of the selected course.

  • TO/FROM Indicator – Displays whether the selected radial will take you toward or away from the station.


Example of Use:

  • A pilot wants to fly TO the VOR on the 090° radial.

  • The OBS is set to 270° (the reciprocal course).

  • The CDI needle centers, and the TO flag appears.

  • The pilot then flies west, staying on course until reaching the station.


Strengths and Limitations of VORs

Strengths

  • Greater accuracy compared to older systems like NDBs (typically within ±1°).

  • Easy to interpret with cockpit instruments.

  • Still widely available as GPS backup.


Limitations

  • Line of Sight – Since VORs operate on VHF, reception requires clear line of sight to the station. Terrain and obstacles can block signals.

  • Cone of Confusion – Directly over the VOR, signals become unreliable.

  • Declining Network – Many VORs are being decommissioned in favor of GPS, although a minimum operational network (MON) will remain for backup.


VORs in Modern Aviation

While GPS and RNAV dominate today’s navigation landscape, VORs continue to serve as critical backup aids. The FAA is gradually reducing the number of VORs but has committed to maintaining a VOR MON (Minimum Operational Network) across the U.S. to provide navigation guidance in the event of GPS outages.


For student pilots, mastering VOR navigation remains an essential skill, not only for training but also for practical use in situations where GPS may fail.


Conclusion

The VHF Omnidirectional Range (VOR) system has been a cornerstone of aviation navigation for decades. Though the aviation industry increasingly relies on satellite-based systems, VORs remain relevant and useful as both a backup and training tool. By understanding how to tune, interpret, and fly with VORs, pilots can ensure safer and more reliable navigation in all types of airspace.



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