How to Do a VOR Check for Safe Navigation

A VHF Omnidirectional Range (VOR) check is a critical procedure for pilots to ensure the accuracy of their aircraft’s navigation equipment. VOR systems are widely used for en-route navigation and instrument approaches, and verifying their functionality is a regulatory requirement under FAA standards (14 CFR 91.171). This blog post provides a clear, step-by-step guide on how to perform a VOR check, whether you’re a student pilot or a seasoned aviator.

What is a VOR Check?

A VOR check confirms that your aircraft’s VOR receiver is functioning within acceptable tolerances. The FAA requires that VOR equipment be checked every 30 days for aircraft operating under Instrument Flight Rules (IFR). The maximum allowable error is typically ±4° for ground checks and ±6° for airborne checks, depending on the method used.

Types of VOR Checks

There are four main types of VOR checks:

  1. VOT (VOR Test Facility): A designated ground-based VOR test signal.
  2. Ground Checkpoint: A specific point on an airport with a known VOR radial.
  3. Airborne Checkpoint: A designated airborne location with a published radial.
  4. Dual VOR Check: Comparing two VOR receivers in the aircraft.

Below, we’ll walk through the steps for each method.

Step-by-Step Guide to Performing a VOR Check

1. VOT Check

A VOR Test Facility (VOT) transmits a signal that should read 0° FROM or 180° TO when tuned in.

  • Locate a VOT: Check the Airport/Facility Directory (A/FD) or chart supplement for a nearby VOT frequency.
  • Tune the VOR receiver: Set the VOR frequency on your navigation radio.
  • Center the CDI: Rotate the Omni-Bearing Selector (OBS) until the Course Deviation Indicator (CDI) centers with a FROM flag.
  • Verify the radial: The OBS should read 0° (±4°) with a FROM flag or 180° (±4°) with a TO flag.
  • Log the results: Record the date, location, frequency, error, and your signature in the aircraft logbook.

2. Ground Checkpoint Check

Airports often have designated VOR checkpoints marked on taxiways or ramps.

  • Find the checkpoint: Refer to the A/FD or airport diagram for the checkpoint’s location and published radial.
  • Position the aircraft: Taxi to the designated checkpoint, ensuring proper alignment.
  • Tune and identify: Set the VOR frequency and confirm the station’s Morse code identifier.
  • Center the CDI: Adjust the OBS until the CDI centers with a FROM flag.
  • Check the error: Compare the OBS reading to the published radial. The difference should be within ±4°.
  • Log the results: Note the details in the aircraft logbook.

3. Airborne Checkpoint Check

This is performed while flying over a designated checkpoint.

  • Identify the checkpoint: Use the A/FD or sectional chart to find an airborne checkpoint and its radial.
  • Tune and verify: Set the VOR frequency and confirm the station’s identity.
  • Fly over the checkpoint: Maintain stable flight and center the CDI with a FROM flag.
  • Check the error: The OBS reading should be within ±6° of the published radial.
  • Log the results: Record the check details.

4. Dual VOR Check

If your aircraft has two VOR receivers, you can compare them.

  • Tune both receivers: Set both VORs to the same ground-based VOR station.
  • Center the CDIs: Adjust the OBS on each receiver to center the CDI with a FROM flag.
  • Compare readings: The difference between the two OBS settings should be within ±4°.
  • Log the results: Document the check in the logbook.

Tips for a Successful VOR Check

  • Always identify the station: Listen to the Morse code or voice identifier to confirm you’re tuned to the correct VOR.
  • Check signal strength: Ensure the VOR signal is reliable, especially for airborne checks.
  • Know your tolerances: Ground checks allow ±4° error, while airborne checks allow ±6°.
  • Log: Include all required details (date, place, bearing error, and signature) to comply with FAA regulations.
  • Consult the FAR/AIM: Review 14 CFR 91.171 for legal requirements and tolerances.

Common Mistakes to Avoid

  • Misidentifying the station: Always verify the VOR’s Morse code or voice identifier.
  • Improper aircraft alignment: Ensure the aircraft is correctly positioned at ground checkpoints.
  • Ignoring the logbook: Failing to log the check can lead to non-compliance with IFR requirements.
  • Using a weak signal: A weak or fluctuating signal can lead to inaccurate readings.

Why VOR Checks Matter

Accurate VOR equipment is essential for safe navigation, especially in low-visibility conditions. A failed VOR check could indicate a malfunctioning receiver, which could compromise your ability to navigate or execute an instrument approach. Regular checks ensure your equipment is reliable and compliant with FAA standards.

Conclusion

Performing a VOR check is a straightforward but essential task for IFR pilots. By following the steps outlined above and adhering to FAA tolerances, you can ensure your navigation equipment is ready for safe flight. Whether you’re using a VOT, ground checkpoint, airborne checkpoint, or dual VOR check, always verify, log, and double-check your work. Safe flying starts with reliable navigation!

For more aviation tips, check out our other posts on instrument procedures and flight planning.

Disclaimer: Always consult the FAA’s FAR/AIM and your aircraft’s operating manual for specific requirements. This guide is for informational purposes and not a substitute for professional training.