FAA ACS Knowledge Test Code: PA.VI.B.K1

  VOR Navigation - Where Am I?
The Private Pilot Knowledge test includes several questions that require you to choose the correct VOR indicator from a graphic. The questions will describe your location based on a position on a sectional chart. Your job will be to select the VOR indicator that corresponds to that location. This is something of a reverse exercise. In the real world you would generally use the VOR indicator to find a position on the chart, not the other way around.

But your first goal is to master the questions so that you get them right on the test. A side effect of this is

that you will learn a shortcut for approximating your position in real world flight. This is actually a very handy little trick and one that is easy to learn.

First of all, remember that radials extend outward from the VOR transmitter. They start at the station and extend outwards like the spokes on a wheel. There are 360 of these imaginary spokes, each named to match their magnetic outbound bearing. You define your position as being on one of these radials. The aircraft's heading is irrelevant.
(For more information, view the "VOR Navigation" lesson at the Gold Seal Ground School.)

Here's the Trick:

You can roughly locate your position in relation to the VOR simply by looking at the CDI needle and the To/From flag.
Experiment with this using the interactive graphic below.

(Scenario 1)  If the needle is centered with a From flag, you are on the radial indicated at the top of the indicator. If the needle is centered with a To flag, you are on the radial indicated at the bottom of the indicator.

(Scenario 2)  If the To/From flag is "off" or not visible, you are located in the Zone of Ambiguity. This is roughly a 20 pie slice to the left or right of the indicator dial. If the needle is left, use the pie slice on the right. If the needle is right, use the pie slice on the left. (If this is confusing, click on #3 and #7 in the graphic below.)

(Scenario 3)  If the needle is either left or right and a To/From flag is shown, your aircraft's position lies in the indicator's quadrant that is opposite from the needle and flag. You are where the needle and flag isn't. If the needle is to the left, you are in the right half of the dial. If the flag is "To", you are in the lower half of the dial. Put these two together and you are in the lower right quadrant.
 

Below is Fig 29 from the Knowledge Test Supplement. This is the graphic you will use in your written test.
The only difference is that this one is interactive. Look at each indicator below and imagine roughly where your aircraft is located. Then click the indicator to see the explanation.

 

These little shortcuts work well in helping you to answer the test questions and are even good for roughly approximating your position without any knob turning. But remember, they are imprecise. To find your location in the air, center the CDI needle with a From flag and read the radial from the top of the gauge. Fly toward the station with a To flag and fly away from the station with a From flag.

Below are four sample questions from the Knowledge Test. Click to view them.

                              

To ace these questions, first locate the hypothetical aircraft on the chart and approximate the radial that it is positioned on.
Write it down. Next, find the three VOR indicators on Figure 29 that are offered as answers. Ignore all the rest.
Then, use the "trick" to determine the answer.
Try it out with the animated figures above.

 

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