VOR
Introduction
What is a VOR ?
- A VOR is a ground based radio navigation aid.
- A VOR on its own does not indicate distance, a DME is usually used for this.
- VORs are aligned with magnetic north (at one point in time).
- VORs radiate on one frequency, which is encoded with two signals.
- VORs operate in the VHF range of radio frequencies.
What Does VOR Do For Us?
- Allows us to determine our RADIAL position relative to the VOR Ground Station.
What Does VOR Not Do For Us?
- Indicate aircraft heading.
The Heading on the VOR indicator is the radial selected by the pilot, it is NOT the direction the aircraft is pointing.
Sorry to labour the point but this is the usual reason people get confused when using the VOR.
What Does VOR stand for ?
- Very High Frequency
- Omnidirectional
- Range
Tips for Using the VOR
This is a VOR/ILS Indicator as installed in many light helicopters.
- OBS
- Omni Bearing Selector
- GS
- Glideslope Flag - Visible When no Glideslope signal received.
- NAV
- Navigation Flag - Visible When Radial signal not received, or outside displayable limits.
- Numbers
- The Number Next to the upper arrowhead is the selected Radial.
The process of verifying that the VOR is working is the same for most Navaids. One important and often missed step in confirming the operation of the VOR is checking the NOTAMS.
- Tune - Dial up the correct frequency on the front panel of the receiver.
- Identify - Listen for the Correct Morse Code Identifier, confirm not transmitting 'TEST' .
- Test - Center The Indicator and check that the selected heading changes by 10 degrees at full scale deflection.
- Select - Select the desired Radial using the knob on the instrument.
Example Content
Correct interpretation is the key to VOR usage, time wasted trying to decipher what is displayed is too valuable in an instrument envrionment, you must be able to look at the VOR indicator and decipher it immediately.
- The heading of the aircraft is not important in interpreting the VOR indication.
- The beacon is in either the upper or lower hemisphere of the indicator, shown by the TO/FROM flag.
- The beacon is on a bearing of OBS hdg ±CDI deviation.
With a TO flag left is minus right is plus.
With a FROM flag left is plus and right is minus.
Its easier to look at the instrument, look at the end of the needle which on the same side (top or bottom) as the beacon (indicated by the FLAG) and use that as an indicator of whether the radial is + or - the needle.
Example Content
The first thing to remember when trying to find out which radial you are on is that all Radials are from the Beacon. The indicator is able to show you which direction to track to the beacon but this is not directly which radial you are on (it's 180° out).
- To centre the needle and find the radial you are currently on, always turn the OBS away from the needle until the needle centres with a FROM indication
Example Content
Sometimes it is necessary to fly along a radial towards the station
- To centre the needle the quickest way to the beacon turn the OBS towards the needle and centre with a TO indication
Example Content
Tracking a VOR is the act of flying along a radial and making an allowance for the wind in order that the aircraft does not drift off Track.
Example Content
Web References
Online VOR Simulator
A Collection of Simulators and Quizzes
An alternative look at VOR navigation [The best way to do it]
Never Get Lost Book
A Flash VOR Simulator
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