How do you read VOR radials and bearings on an OBI or HSI?

Select the desired course; a centered needle with a TO indication means you are on the reciprocal radial inbound, while a FROM indication means you are on the selected radial outbound.

What is the difference between a VOR radial and a VOR bearing?

A VOR radial is the magnetic bearing FROM the station, while a VOR bearing TO the station is the reciprocal (radial + 180°).

Why must magnetic variation at the VOR station be considered?

Because VOR radials are referenced to magnetic north at the station; to convert to true bearings, apply the station's variation.

What does the TO/FROM flag on a VOR indicator mean?

It shows whether the selected course will take you TO the station (QDM) or FROM the station (QDR) when the needle is centered.

What is scalloping in VOR indications?

Scalloping refers to fluctuating or erroneous VOR indications caused by signal reflections from terrain, bending the radials.

VOR Radials and Bearings

Hard4 min readRadio Navigation

Moderately Examined

Why this matters

Precise understanding of VOR radials and bearings is essential for safe navigation, especially when flying under instrument flight rules. Misinterpreting VOR indications can lead to navigation errors, airspace infringements, or even controlled flight into terrain.

VOR radials and bearings are fundamental to radio navigation, allowing pilots to determine their position and track relative to a VOR station. Understanding how to read VOR indications, interpret radials (magnetic bearings FROM the station), and bearings TO the station is essential for accurate navigation and safe flight operations.

Quick Check

On a VOR, what does the radial represent?

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In depth

Explanation

VOR Radials Explained

A VOR (Very High Frequency Omnidirectional Range) transmits signals that define 360 radials, each corresponding to a magnetic bearing FROM the station. The radial you are on is the magnetic direction from the VOR to your aircraft, referenced to magnetic north at the VOR's location.

Bearings TO and FROM the VOR

The radial (QDR) is the magnetic bearing FROM the station to the aircraft.
The reciprocal, or QDM, is the magnetic bearing TO the station from the aircraft (radial + 180°).
To convert a radial to a true bearing, apply the magnetic variation at the VOR station.

Reading VOR Indications

On an Omni-Bearing Indicator (OBI), select a course; the instrument shows deviation from that course and whether you are heading TO or FROM the station.
On a Radio Magnetic Indicator (RMI), the tail of the VOR needle points to the radial; the tip points to the reciprocal (bearing TO the station).
The Horizontal Situation Indicator (HSI) combines heading and VOR data, showing angular displacement from the selected course.

Tracking and Position Fixing

To track a radial inbound or outbound, set the desired course and fly to center the deviation indicator, correcting for wind drift.
To change radials, intercept the new radial by turning to an appropriate heading and adjusting as you approach.
VOR position fixing can be achieved by cross-checking radials from two stations.

Station Passage and Abeam Point

Station passage is indicated when the TO/FROM flag flips and the deviation needle centers.
The abeam point is when the station is directly off your wing, usually indicated by the fastest rate of change in the TO/FROM indicator.

VOR Types

Conventional VOR (CVOR): Uses a rotating antenna.
Doppler VOR (DVOR): Uses fixed antennas and the Doppler principle for improved accuracy.
En-route VOR: For airway navigation.
Terminal VOR (TVOR): Shorter range, for approach/departure.
Test VOR (VOT): For receiver accuracy checks, emits a constant phase.

Errors and Scalloping

Reflections from terrain can cause 'scalloping', leading to fluctuating or incorrect indications. Doppler VORs are less susceptible to this error.

The essentials

Key Points

VOR radials are magnetic bearings FROM the station, referenced to the station's magnetic north.

To convert a VOR radial to a true bearing, apply the station's magnetic variation.

The OBI shows course deviation and TO/FROM; the RMI's tail points to the radial, tip to the reciprocal.

Aircraft heading does not affect the VOR radial indication.

Tracking a radial requires wind correction to stay on course.

Scalloping errors can occur due to signal reflections, especially with conventional VORs.

Different VOR types serve en-route, terminal, and testing functions.

Watch out

Exam Traps & Typical Mistakes

Confusing the bearing TO the station (QDM) with the radial (QDR, FROM the station).

Forgetting to apply magnetic variation at the VOR station, not at the aircraft, when converting to true bearings.

Assuming aircraft heading affects VOR radial indication—it does not.

Misreading the TO/FROM indicator and flying the reciprocal course.

Overlooking the effect of wind drift when tracking a radial.

Test yourself

Example Exam Questions

Question 2Medium

When converting a VOR radial to a true bearing, what must be taken into account?

Question 3Medium

On a Radio Magnetic Indicator (RMI), what does the tail of the VOR needle indicate?

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