Another popular method of aviation navigation is by ground-based radio signals. For many years aircraft have been fitted with radio receivers to pick up signals that indicate the position of the aircraft relative to the radio transmitter. The most popular for small aircraft is the VHF omnidirectional range (VOR). There are two types of radios on many aircraft: navigation and communication. As a private pilot, you should know how they work and why you should have them.
VOR is a ground-based electronic navigation aid transmitting very high frequency (VHF) radio signals in all directions. Receiving equipment in an aircraft can identify the location, relative position, and (if equipped) distance to or from the VOR transmitter.
The VOR system uses a frequency that is just above FM radio band. To use it, you select a specific radial (such as 270 degrees) signal and fly either to or from the station. The VOR has 360 radials radiating from the station that allow you to fly any direction on the compass. There are a few variations to the VOR system. You’ll hear them referred to as VORTAC, meaning VHF omnirange/tactical air navigation system, a mouthful that means it’s a VOR that the military uses, too. And you’ll see references to VOR-DME or NDB-DME, which means the signal can be read by aircraft with distance measuring equipment (the DME part) to also tell you how far you are from the VOR. There will be knowledge test questions on these systems and how to use them so refer to your FAA publications for the official mantra.
"Man cannot discover new oceans unless he has the courage to lose sight of the shore."
-- Andre Gide