This story was made in partnership with AOPA. Ready to join the largest aviation community in the world? Sign up and become an AOPA Member today.

Every IFR pilot learns how to use VORs. Here are some things you may not know...

1) What Does VOR Stand For?

VOR stands for VHF (very high frequency) omni-directional range radio. This is a 30-300 MHz frequency band.

2) Available VOR NAVAID Frequencies

You'll find VOR frequencies available between 108.00 MHz and 117.95 MHz. Between 108.00 MHz and 112.00 MHz, even tenths are reserved for VORs and odd tenths are reserved for localizer (LOC) NAVAIDs.

3) Each VOR Has 2 VHF Signals

One is all-directional, known as the reference phase. The other is rotating, called the variable phase. Your VOR receiver interprets the difference between these signals to determine what radial you're flying on from the VOR.

4) Service Volume Levels

There are three legacy service volumes of terminal, low, and high VORs. And now there are new services volumes of Low (VL) and High (VH) that support 70 NM service starting at 5,000'. You can find which type of VOR you'll be using in your chart supplement.

5) Line Of Sight

VORs are based on line-of-sight. If terrain or the horizon obscures a direct path between your airplane and the VOR, it will be unusable.

6) Avoid Reverse Sensing

Always have the aircraft heading match the VOR course you've set. If they're reversed, you put yourself at risk for reverse sensing.

7) 30 Day VOR Checks

To fly IFR, a VOR check must have been performed within the past 30 days (14 CFR Part 91.171). The date, location, noted VOR errors, and the pilot's signature must be entered into the aircraft logbook.

What else should pilots know about VORs? Tell us in the comments below.

Ready to join the largest aviation community in the world? Sign up and become an AOPA Member today.