VOR Checks in Aviation: Ensuring Accuracy and Safety

wifiCFI
Aug 31
3 min read

The VHF Omnidirectional Range (VOR) system has been a cornerstone of aviation navigation for decades. While satellite-based systems like GPS dominate modern navigation, VORs remain a critical backup. To ensure safety and compliance, the FAA requires pilots to verify the accuracy of their aircraft’s VOR equipment regularly. This process is called a VOR check.

Understanding how to properly perform VOR checks is essential, not only for legal compliance but also for ensuring the accuracy of navigation during flight.

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Why VOR Checks Are Important

A VOR receiver that provides inaccurate information can mislead a pilot by miles, especially over long distances. The FAA mandates that pilots must perform a VOR check every 30 days if the VOR system is to be used under Instrument Flight Rules (IFR). The results of these checks must also be logged, including:

Date of check
Location of check
Error observed (if any)
Signature of person performing the check

The maximum allowable error depends on the type of check, but typically it must not exceed ±4° on the ground and ±6° in the air.

Types of VOR Checks

There are several methods pilots can use to verify the accuracy of their VOR system.

1. VOT Check (VOR Test Facility)

A VOT (VOR Test Facility) is a special ground-based transmitter located at certain airports. It transmits a test signal that allows pilots to verify VOR accuracy.

Procedure:
- Tune the VOR receiver to the VOT frequency (published in the Chart Supplement).
- Set the OBS to 360° FROM or 180° TO.
- The CDI needle should center, and the TO/FROM indicator should display correctly.
Allowable Error: ±4°

This is one of the most precise and reliable methods, but not all airports have a VOT available.

2. Ground Check (Designated VOR Checkpoints)

Many airports have VOR ground checkpoints, usually located on the ramp or taxiway, marked by a sign. These checkpoints are designed for pilots to test their receivers before departure.

Procedure:
- Tune and identify the VOR station.
- Position the aircraft at the marked checkpoint.
- Set the OBS to the published radial for that checkpoint.
- The CDI should center, and the TO/FROM indicator should match the expected indication.
Allowable Error: ±4°

This is a quick and convenient way to verify accuracy before flight.

3. Airborne Check

If no ground facilities are available, a pilot can perform a check in flight using designated airborne checkpoints. These are published points where the correct radial to/from a VOR is known.

Procedure:
- Fly over the published checkpoint at the designated altitude.
- Tune and identify the VOR.
- Set the OBS to the published radial.
- Verify the CDI needle centers within tolerance.
Allowable Error: ±6°

Airborne checks are especially useful at airports that lack ground-based checkpoints.

4. Dual VOR Check

If the aircraft is equipped with two independent VOR receivers, they can be checked against each other.

Procedure:
- Tune both VOR receivers to the same VOR station.
- Set both OBS knobs to the same radial.
- Compare the CDI indications.
Allowable Error: 4° between the two receivers.

This is a common and practical check, especially in IFR-equipped aircraft.

Conclusion

VOR checks are a simple yet critical procedure that ensures navigation accuracy and compliance with FAA regulations. By performing VOT checks, ground checks, airborne checks, or dual VOR checks, pilots can confirm their equipment is functioning correctly and avoid the risk of being misled during IFR operations.

Even in an era dominated by GPS, mastering these skills keeps pilots prepared, professional, and safe.

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