Learn how to use a VOR (VHF Omnidirectional Range) to navigate to or from a ground station.
You will learn how to read a VOR indicator, understand radials, select a course, and follow or intercept a VOR course during flight.
Learn what a VOR station is and how radials help you determine your position.
Learn to use the OBS, CDI needle, and TO/FROM indication to understand your selected course.
Follow a VOR course, make corrections, and learn how to intercept a new course.
GPS is common in modern airplanes, but VOR navigation is still a useful skill for student pilots. It gives you another way to follow a route and check your position during flight.
VOR indications can be confusing at first. The needle may move left or right, but the correct response depends on the course you have selected.
This lesson uses simple explanations and practical examples to help you understand the instrument before using it in the airplane.
What Is a VOR and How Does It Work?
VOR stands for VHF Omnidirectional Range. It is a ground-based radio navigation system used in aviation.
A VOR station sends radio signals that an airplane can receive. These signals help the pilot determine the airplane's direction from the station and follow a selected course.
Three Parts of a VOR System
VOR Station
The ground station transmits VHF radio signals. Each station has its own assigned frequency.
VOR Antenna
The aircraft antenna receives the VOR signal and sends it to the onboard NAV receiver.
VOR Indicator
The NAV receiver processes the signal. The VOR indicator then shows guidance for the selected course.
VOR Frequency and Reception Range
VOR stations operate in the VHF band. Their signals travel mainly by line of sight. This means the airplane needs a sufficiently clear path to receive a reliable signal.
Pilots select the appropriate station frequency on the aircraft's NAV radio.
Aircraft altitude, terrain, and the station's published service volume affect the area in which its signal can be used reliably.
Flying higher often improves reception, but does not guarantee it.
A basic VOR provides directional guidance, not distance to the station. Distance information requires separate equipment, such as DME (Distance Measuring Equipment).
VOR navigation uses radio signals from a ground station. To use the system, the aircraft must receive a reliable signal. The VOR indicator then helps the pilot follow a selected course.
How to Read a VOR Indicator
A traditional VOR indicator shows the position of a selected course relative to your airplane.
To read it correctly, you need to understand four parts: the OBS, the CDI needle, the TO/FROM indicator, and the deviation dots.
The Four Main Parts of a VOR Indicator
Turn the OBS knob to select a course. Read the selected course at the top of the instrument.
The CDI needle moves left or right. It shows how far you are from the selected course.
TO means the selected course leads toward the station. FROM means it leads away from the station.
On a typical VOR indicator, each dot represents 2° of course deviation. Full deflection is normally 10°.
What Does the CDI Needle Tell You?
When you are flying in the direction of the selected course with the correct TO/FROM indication, you can read the needle as follows.
You are on the selected VOR course.
The selected course is to your left.
The selected course is to your right.
The TO/FROM indicator does not tell you whether the airplane is currently flying toward or away from the station.
It describes the selected course relative to the station. Before using the CDI to make a course correction, make sure the OBS is set for the direction you intend to fly.
If the course is selected in the opposite direction, the CDI may give reverse sensing. We will examine this during the tracking exercises.
The OBS selects a course. The CDI shows deviation from that course. The TO/FROM indicator shows whether the selected course leads toward or away from the VOR station.
VOR Radials and Aircraft Position
A VOR station has 360 radials. A radial is an imaginary line extending outward from the station.
Each radial is named for its direction FROM the station, using degrees based on magnetic north.
How Are VOR Radials Numbered?
Imagine a compass with the VOR station at its center. Every degree marks a different radial.
For example, an airplane on the 090° radial is east of the VOR station.
Radial vs. Course: What Is the Difference?
A radial always points away from the station. But an airplane can fly in either direction along the same line.
Imagine your airplane is east of a VOR station, on the 090° radial.
Select the 270° course to travel toward the station along the 090° radial.
Select the 090° course to travel away from the station along that radial.
Your position on a radial does not change just because you turn the airplane. A VOR radial describes where you are relative to the station, not the direction your nose is pointing.
How Do You Find Your VOR Radial?
Once you have a reliable VOR signal, you can use a traditional VOR indicator to find the radial you are on.
With the correct VOR station tuned and identified, turn the OBS until the CDI needle is centered with a FROM indication.
Read the number at the top of the OBS. This is the radial you are on.
Find that radial on your aeronautical chart to see your direction from the station.
Remember that one radial identifies a line of position, not an exact point on the chart. You need more information to determine your precise location.
Radials are always measured FROM the VOR station. To find your radial, center the CDI with a FROM indication and read the OBS setting.
Tuning, Identifying and Checking a VOR
Before following a VOR course, you must select the correct station and identify its signal. You should also know how to check the accuracy of your VOR receiver.
Tune and Identify the Station
Use your aeronautical chart and the aircraft's NAV radio. Follow these three steps:
-
01
Find the VOR frequency
Locate the station on your current chart. Note its frequency and three-letter identifier. Check for any NOTAMs affecting the station.
-
02
Select the frequency
Enter the frequency in your NAV radio. If your radio has an active and standby frequency, make sure the correct one is active.
-
03
Identify the station
Listen to the station's Morse code and compare it with the identifier on your chart. You may also use a valid automatic identification from your equipment.
Two stations may use the same frequency in different areas. A correct frequency does not guarantee the correct station.
If the identifier is missing, incorrect, or replaced by a TEST code, do not use that station for navigation.
Check the Receiver with a VOT
A VOT (VOR Test Facility) sends a special test signal. It lets you check whether your VOR receiver indicates the correct course.
Find an available VOT and its frequency in the Chart Supplement. Tune that frequency and listen for the test signal, which may be dots or a continuous tone.
Now turn the OBS until the CDI is centered. You should get one of these two readings:
Example: If the CDI centers at 003° FROM, the error is 3°. This is within the permitted 4° limit.
A reading of 006° FROM would exceed the limit.
Other Ways to Check a VOR Receiver
A VOT is not available everywhere. Other checks are permitted under specific conditions.
Compare the receiver with a designated VOR checkpoint on the airport surface.
Fly over a published airborne checkpoint and compare the indicated bearing.
Use an established airway radial and a suitable ground landmark when this method is permitted.
Compare two independent VOR receivers tuned to the same station. Their readings must agree within 4°.
These methods have specific conditions. For example, the landmark method uses an established airway radial, not just any point on a chart.
In the United States, when using VOR navigation under IFR, an operational accuracy check must have been completed within the preceding 30 days, unless an approved maintenance and inspection procedure applies. This is not a general VFR requirement.
For a required operational check, record the date, place, bearing error, and signature in the aircraft log or another appropriate record.
Select the correct station, confirm its identifier, and check that the equipment is suitable for the flight. Do not rely on an unidentified signal or a receiver that fails a required accuracy check.
Tracking TO and FROM a VOR Station
VOR tracking means keeping your airplane on a selected course as you fly toward or away from a VOR station.
The diagrams below show the airplane's position and the matching VOR indicator. This makes it easier to see why the CDI needle moves left or right.
Tracking Toward the Station
Imagine you are south of a VOR station and want to fly north toward it.
-
1
Select the course
Set the OBS to 360° and confirm a TO indication.
-
2
Watch the needle
In the diagram, the airplane is left of the selected course. The CDI needle is therefore to the right.
-
3
Correct right
Turn toward the selected course. As the CDI moves toward center, reduce the correction.
-
4
Maintain the course
Once established, use a heading that keeps the CDI centered. Correct for any wind drift.
Look at both sides of the diagram: the airplane is left of the dashed blue course line, so the CDI needle appears right of center.
Tracking Away from the Station
Now imagine you are flying northwest, away from the station. You want to follow the 300° radial.
-
1
Select the course
Set the OBS to 300° and confirm a FROM indication.
-
2
Check your position
In the diagram, the airplane is right of the selected radial. The CDI needle is left.
-
3
Correct left
Turn toward the selected radial. Watch the CDI move back toward center.
-
4
Maintain the radial
Once established, use a heading that keeps the CDI centered, allowing for wind.
Compare the two diagrams: the CDI tells you on which side of the airplane the selected course lies, provided you are tracking in the selected OBS direction.
Use the same method when tracking inbound or outbound.
Observe which way the CDI moves away from center.
Turn toward the selected course and watch the needle return.
Adjust the heading for wind to keep the CDI centered.
Understanding Reverse Sensing
Reverse sensing occurs when you try to use CDI guidance while flying in the opposite direction from the selected OBS course.
The CDI still responds to the selected course, but its left/right indication may seem reversed relative to your intended direction.
Your intended course is 360° TO.
If the OBS is set to 180° FROM, the instrument is set for the opposite direction.
Set the OBS to 360° TO before using the CDI for northbound tracking.
Compare the aircraft positions and course indications in the illustration. Remember that TO/FROM does not tell you which way the aircraft is currently moving.
Select the course that matches your intended direction of flight. When tracking in that direction, use the CDI to see where the course lies and make measured corrections. Adjust your heading for wind to maintain the course.
Intercepting a VOR Radial
When your airplane is not on the VOR course you want to follow, you must first intercept that course.
Select the desired course, choose a heading that will cross it, and watch the CDI move toward center. Then turn onto the course and maintain it.
Intercepting a Course Toward the Station
Imagine your airplane is southwest of a VOR station. You want to join a northbound course and fly toward the station.
-
1
Select the course
Set the OBS to 360° and confirm a TO indication.
-
2
Read the CDI
The CDI is to the right. The selected course is to your right.
-
3
Fly an intercept heading
For this example, turn to 045°. This is a 45° intercept to the right of the desired course.
-
4
Capture the course
As the CDI approaches center, begin turning toward 360°. Then maintain the course, correcting for wind.
This illustration uses a different inbound course from the first diagram.
The airplane starts near the 060° radial. The desired course is 270° TO, which follows the 090° radial toward the station.
The pilot flies a 180° intercept heading, crossing the desired course at 90°. As the CDI approaches center, the pilot turns west to track 270° TO.
This shows a steeper intercept than the 45° example above. Neither angle is mandatory for every situation.
View the original illustration at full size ↗Intercepting a Course Away from the Station
Now imagine your airplane is southeast of the station. You want to join the 090° radial and fly east.
-
1
Select the radial
Set the OBS to 090°. Confirm a FROM indication.
-
2
Read the CDI
The needle is left. The desired radial lies to your left.
-
3
Choose an intercept heading
In this example, fly 045°. This is a 45° intercept toward the selected radial.
-
4
Join the radial
As the CDI approaches center, begin turning toward 090°. Then maintain the radial with any needed wind correction.
This illustration uses the same selected outbound radial as the second diagram, but a different intercept angle.
The airplane begins south of the 090° radial. The CDI indicates that the desired course is to the left.
The pilot flies 060°, intercepting the radial at an angle of 30°.
After reaching the radial, the pilot turns to 090° and adjusts for wind drift.
Compare this 30° intercept with the earlier 45° example. Both are possible, but the angle changes how quickly the airplane reaches the course.
View the original illustration at full size ↗
Different Headings, Same Desired Course
This third illustration shows a course of 280° TO, the reciprocal of 100° FROM.
An airplane can approach this course from either side. The illustration shows one approach at 235° and another at 310°.
The important point is that the chosen heading must actually bring the airplane toward the desired course.
The intercept angle is not always 45° or 90°. Choose an appropriate angle based on your position, speed, distance from the station, wind and the procedure being flown.
Remember: a CDI needle at full deflection does not tell you exactly how far the airplane is from the selected course. As the needle moves toward center, prepare to turn onto the course without overshooting it.
Set the correct OBS course and confirm the TO/FROM indication. Choose a heading that will cross the desired course and monitor the CDI as you approach it. Begin the turn onto the course as the needle approaches center, then correct for wind to maintain your ground track.
Station Passage and VOR Limitations
When you fly directly over a VOR station, the instrument may behave differently from what you see during normal tracking. Knowing what to expect helps you avoid unnecessary heading corrections.
What Happens When You Pass a VOR Station?
Imagine you are flying north toward a VOR station, with the OBS set to 360°. Watch how the TO/FROM indication changes as you pass the station.
CDI centered. The instrument shows 360° TO.
You are approaching the VOR.The CDI may fluctuate, and TO/FROM may change or briefly become unreliable.
Illustrative indication only.With the same OBS setting, the indication settles to 360° FROM.
You are now north of the VOR.How Do You Recognize Station Passage?
As you approach the station, the CDI can become more sensitive. Small changes in your position may cause larger needle movements.
Close to the station, the CDI may fluctuate rapidly. After passing the VOR, the TO/FROM indication reverses and the needle becomes stable again.
The change from TO to FROM is the important indication of station passage. A complete CDI deflection is not required.
What Should the Pilot Do?
- Maintain the heading that was keeping you on course during brief station-passage fluctuations.
- Avoid chasing rapid CDI movements near the station.
- Confirm that the TO/FROM indication has reversed.
- Resume normal CDI tracking once the indications become stable.
If your route continues north along the same line, you can keep the OBS at 360°. If the next leg uses another course, follow the appropriate procedure for that leg.
Understanding VOR Signal Limitations
A VOR does not provide reliable navigation guidance at every altitude or distance. Signal reception depends on the station, surrounding terrain and obstacles, and the aircraft's position.
VOR signals generally travel by line of sight. Mountains, obstacles and low altitude can reduce or block reception.
Each VOR has a published coverage area that depends on its type and altitude. Reception outside that area is not necessarily reliable.
Signal disturbances, interference or equipment problems can cause needle fluctuations or warning flags. Do not rely on indications that are unreliable.
The area directly above a VOR may not provide useful directional information. Expect brief fluctuations rather than continuous, precise guidance.
During station passage, expect possible CDI fluctuations and look for the TO/FROM reversal. Avoid unnecessary heading changes while the indications are unstable. Outside the station area, always consider signal coverage, terrain and instrument reliability before using VOR guidance.
Interactive VOR Simulator
Move the airplane on the map or change the OBS. Watch the CDI needle and the TO/FROM indicator. Use this simulator to practice reading the CDI, tracking VOR courses, and understanding course interception.
Try These VOR Examples
Choose an example, then change the OBS or move the airplane to see what happens.
- Select 090° FROM. The CDI is centered because the airplane is on the 090° radial.
- Select 270° TO. The airplane has not moved, but the indicator now shows the inbound course.
- Select Reverse Sensing. The airplane is flying east, but the OBS is set to the westbound course. Try changing the OBS to 090°.
Training aid only. The map distance is simulated; a VOR alone cannot measure distance. Magnetic directions are simplified and wind is not modeled. The small station-passage area is illustrative, not a real coverage limit. This tool does not simulate terrain, signal errors, equipment failures, or actual service volumes. Always use current FAA guidance and your aircraft equipment instructions in flight.
VOR Review Questions
Test your understanding of VOR navigation. Try to answer each question before revealing the explanation.
These questions cover station identification, radials, TO/FROM indications, tracking, interception and station passage.
Part 1 — Check Your Knowledge
Show Answer
Find the frequency and identifier on a current aeronautical chart. Tune the NAV radio and identify the received station using its Morse code identifier or another valid identification method supported by your equipment.
Show Answer
After tuning and identifying the station, rotate the OBS until the CDI is centered with a FROM indication. The selected bearing identifies the radial.
Remember that a radial alone does not tell you how far you are from the station.
Show Answer
The 090° radial extends east from the station. To fly back toward the VOR, select its reciprocal course, 270°, with a TO indication.
Once established, maintain the course and correct for wind as necessary.
Show Answer
The indicator should show FROM because the selected course leads away from the station. A centered CDI means you are on that course line.
Show Answer
Select the desired OBS course and check TO/FROM. Choose a heading that will cross the selected course. Watch the CDI move toward center, then begin turning onto the course to avoid overshooting.
Adjust your heading for wind after joining the course.
Show Answer
During a direct station passage, the CDI may fluctuate or become temporarily unreliable. The TO/FROM indication changes as the airplane crosses the station.
For example, when flying north with OBS 360°, the indication changes from TO before the station to FROM after passing it.
Part 2 — Read the VOR Indicator
Look at each instrument carefully. Use the OBS setting, CDI position and TO/FROM indication to answer the question.
Show Answer
When tracking in the selected OBS direction, a left CDI means the course lies to your left. Turn left enough to bring the needle toward center.
Reduce the correction as you return to the course.
Show Answer
A 270° TO course leads west toward the station. The airplane is on the reciprocal radial, 090°, east of the VOR.
The CDI is centered because the airplane is on the selected course line.
Part 3 — Practical Flight Decisions
Show Answer
The OBS is set to the opposite direction from your intended course. CDI left/right guidance can appear reversed for your direction of flight.
Select 360° TO before tracking northbound toward the station.
Show Answer
The bearing error is 3°, which is within the permitted ±4° VOT tolerance.
006° FROM: Not Acceptable
The error is 6°, exceeding that limit. The equipment does not pass this accuracy check.
If you missed a question, revisit the relevant explanation and try the Interactive VOR Simulator. Practice selecting a course, interpreting TO/FROM, correcting CDI deviations and intercepting a radial.
