VOR Navigation

If you're using the VOR correctly, then the dot in the center is your airplane, and the line is the course you're trying to be on. If the line is to the right, go right. If the line is to the left, go left.

 A VOR has three elements: an omnibearing selector (OBS), a course deviation indicator (CDI), and a TO/FROM indicator.

The OBS allows you to select the line of direction that the VOR tracks.

The CDI indicates how many degrees the aircraft is off that line, and in which direction.

The TO/FROM indicator shows whether following that line's direction would take you to that ground facility, or away from it.


1. Centering the CDI


2. The CDI: If the aircraft is not on the line, the CDI shows a deviation of one dot for every two degrees. Think of the center dot as being the aircraft, and the CDI as being the line you want to be on. If the line is to the right of the dot, get back on it by turning right (as in the example's red aircraft). IMPORTANT: if you are flying away from the VOR station, and the indicator says TO, you will get reverse sensing: the line will be on the wrong side. This is the situation with the blue aircraft in the example: if that plane goes right, toward the CDI needle, it will get farther away from the radial line. The same is true if you are flying toward the station, and the indicator says FROM.  

  3. Location: To find out where you are, find two ground facilities that will give you a good angle between them. Tune each in, and center the needles with a FROM indication. You are on the intersection of those two radials. (If you have only one VOR, then you'll have to flip between their frequencies and recenter.) In this example, the plane is at the intersection of the RED 074º radial, and the GRN 157º radial.

4. VOR Navigation: To fly directly to a VOR, center the needle with a TO indication. Turn to that heading and bracket to stay on the line (see bracketing, below).

To fly from one VOR to another, fly away from one VOR with the needle centered on the appropriate radial and a FROM indication. You can put exactly the same radial into the VOR you're approaching, and it will also line up with a TO indication. If you have only one VOR, switch between the frequencies at the half way point.


5. Intercepting a radial:

Intercepting a radial is a matter of choosing the angle at which you wish to get on the line, and then doing some utterly simple math.

 The most rapid way to get on to a distant radial would be to fly perpendicular, straight to it: a 90º intercept. To intercept a 270º TO course from the south, fly direct north until the needle centers. To intercept that same line (which would also be the 90º FROM radial) from the north, fly directly south.

Usually, though, you'll want to intercept a course at a shallower angle, because that cuts down the total distance and time to your destination. 30º or 45º are good intercept angles, but any angle will do and the math is always the same: take the magnetic course of the line that you're trying to get on. Then, if you're intercepting from the right side of the line, add the intercept angle. If you're intercepting from the left of the line, subtract the intercept angle.

Example: You're trying to intercept the 280º course (TO the station) from south of that line. You choose a 30º intercept. Fly a track of (280º + 30º) = 310º. If you are trying to intercept that same line from the north side, on a 45º intercept, fly a track of (280º - 45º) = 235º. If you were going to fly FROM on that same line, it's the 100º radial. To intercept at a 45º angle from the north, you're now on the left side of the line, so fly (100º + 45º) = 145º. Note that the track is not necessarily the heading: you'll have to crab for wind in order to intercept correctly.

 6. Bracketing

Bracketing is the craft of getting and staying on a direct track to a navigation facility, by making adjustments for wind drift. The idea is this: get on the line and hold a heading. The wind pushes you off the track. Pick a heading to get back to the line, and then split the difference. Repeat until you find the heading that holds the CDI steady, straight up and down.