What is a VOR radial?

A radial is a magnetic course that points outward FROM a VOR station. There are 360 of them, one per degree. Your aircraft is always "on" some radial — the magnetic bearing from the station to your position.

Does aircraft heading affect the VOR indication?

No. A VOR is heading-independent. The CDI needle and TO/FROM flag depend only on where the aircraft is (its radial) and the selected OBS course — not on which way the nose is pointing.

How do you read the CDI and TO/FROM flag?

Set the OBS to the course you want. The course-deviation needle shows how far off that course you are (each dot = 2°, full scale = 10°); fly toward the needle to intercept. The TO/FROM flag tells you whether flying that course takes you toward or away from the station.

Free interactive trainer

VOR Simulator

Drag the aircraft around the station, twist the OBS, and watch the CDI needle and TO/FROM flag react instantly. The fastest way to feel how radials and course tracking actually work — no airplane required.

Top-down map

Tap or drag to move the aircraft

Selected course (OBS) Your radial Aircraft

CDI (course deviation indicator)

Needle left · 5 dots (full scale)

OBS — selected course

360°

Aircraft heading

045°

Spin the heading and watch the CDI: it never moves. A VOR reads your position, not where the nose points.

What the instrument is telling you

Your radial

R045

OBS (course)

360°

Deviation

+45°

Flag

FROM

You are on the R045 radial (magnetic bearing 045° from the station to you). With the OBS set to 360°, the CDI shows the needle deflected to the left (5 dots, 45°) with a FROM flag. To track the 360° course, turn toward the needle (left) to intercept, then center it.

What is a VOR?

A VOR (VHF Omnidirectional Range) is a ground navigation station that broadcasts a signal an aircraft receiver can decode into a precise magnetic bearing. Think of the station as the hub of a wheel with 360 spokes radiating outward — those spokes are radials. Your airplane is always sitting on one of them: the magnetic course pointing from the station out to your position.

Radials, the OBS, and the CDI

You tell the instrument which course you care about by twisting the OBS (Omni Bearing Selector) knob. The avionics then compare your radial to that selected course and drive two things on the CDI (Course Deviation Indicator):

The course needle — a vertical bar that swings left or right to show how far off the selected course you are. Each dot is 2°; full-scale deflection is 10°. The needle always deflects toward the course, so you fly toward the needle to intercept.
The TO/FROM flag — tells you whether flying the selected course would take you TO the station or FROM it. Near 90° off the course, the flag becomes ambiguous and an OFF/NAVflag appears — the indication isn't trustworthy there.

The big idea: a VOR is heading-independent

This trips up almost every student. The CDI does not care which way your nose points. Spin the heading slider in the sim and watch — the needle and flag never budge. The indication depends only on where you are (your radial) and what you selected (the OBS). Heading only matters for deciding which way to turn to chase the needle.

What the FAA written tests

Expect questions that hand you a position and an OBS setting and ask you to predict the instrument, such as:

Which radial the aircraft is on, given its position relative to the station.
Whether the CDI shows TO or FROM for a given OBS setting.
Which way the needle deflects (left/right) and how to turn to intercept and track a course.
That changing heading alone does not change the VOR indication.
Recognizing the ambiguous/OFF zone roughly 90° from the selected course.

Want to type the numbers instead of drag? Try the crosswind calculator, E6B flight computer, or METAR decoder.

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For study and familiarization only. This simplified simulator is not to scale, ignores signal range, slant range, and station limitations, and is not for navigation or flight planning. Always train with a certificated flight instructor and use current, official charts and avionics.