How VORs Really Work

Flight instructors across the nation have been involved in a massive coverup scheme surrounding VOR stations. We’ve all been taught to think of VOR stations as a giant compass rose transmitting radio beams in 360 directions. It is common to refer to a VOR as a giant wheel with 360 spokes representing radials. These are all lies.

Well, not exactly. All conspiracy theories aside, flight instructors have been telling this story for a good reason, it is much easier for pilots to conceptualize a great spoked wheel in the sky than to understand the inner workings of the machine.

It’s the age-old “black-box” argument. It is far more important to be able to use a VOR than to know how it works. That being said, a VOR is a surprisingly simple device.

VOR stations are nothing more than the radio equivalent of a rotating beacon with a flashing strobe. To conceptualize the system, consider the following simplification:

The omnidirectional signal pulses as the unidirectional signal passes north.

Each VOR consists of red unidirectional rotating beacon and a white omnidirectional strobe. The rotating beacon turns at a rate of one degree per second, so that it makes one complete rotation every 360 seconds. Every time the beacon passes through north, the strobe flashes white.

By comparing the time between beacon and strobe flashes, the airplane’s onboard equipment can determine the current radial. For example, if it you were to see a white flash followed by a red beacon 45 seconds later, then you would be on the 45 degree radial from the station.

The VOR system works in exactly this way, except that it uses unidirectional and omnidirectional radio signals instead of beacons and stobes. For accuracy, the unidirectional signal, our “beacon,” rotates at a dizzying 1,800 r.p.m.

Helpful Links:
VOR / ADF Navigation Simulator
Wikipedia’s Article on VORs