What is a VOR? And how it's work??

 

You might have observed this kind of structures near to the every airport, this are nothing but the VOR.

VOR stands for VHF omnidirectional range.

Omnidirectional comes from Latin words Omni which means all or in every direction.

VHF stands for very high frequency which makes the VOR a short range device.

So in line of sight VOR are only receiveble from 25nm upto a 140nm useable radius.

The line of sight meaning, if there is any mountain like this

Then there are chances of signal loss even though you are within the VOR range.

As I mentioned earlier the VOR sends the signal in all 360 degrees direction and this signal are picked up by the OBS reciver which is located at small aircraft like Cessna citation, beechcraft etc. 

In today's blog will use a course deviation indicator as a VOR reciver With a OBS( Omni bearing selector) which is very common in the Cessna-152 and 172 etc. 

Now in our VFR and IFR chart this big Rings 

Indicates  a VOR and it's range, this will come into a three different parts first one is VOR itself 

2.- VOR/DME( distance measuring unit)

3.- TACAN VOR( tactical air navigation

VOR common frequency throughout the world is from 108.0 MHz to 118.0 MHz and with 50khz spacing

Ok now let's talk about how it's work imagine a below picture

The white light transmitting in all direction and the red light rotating around. If the red light crosses the magnetic north and white light goes up then you start a timer and wait till red light passes your plane. Like this below-

If the rotation speed, let say  60sec per 360 degrees and we just timed 20sec Then

That would means 60sec= 360 degrees

                                   20sec= ?

So the 20×360÷ 60=  120 degrees.

That means our aircraft is on 120 degrees radial.

 This is how our VOR reciver works.

Now what is a radial, think that our VOR radiating signals to the 360 degrees.

Whenever our instructor or ATC says-  

Air India 272  fly on radial 220 from BBB( Mumbai VOR).

Then you immediately knows that you have to fly away from the station like below-

VOR are most common among general aviation and also used on the modern aircrafts( commercial aviation) in case of GPS failure and most of the time pilot always prefer the VOR navigation i.e. radial.

Radial gives the your actual position from the station or airport.

The VOR are modernize to perform the wide range of activities also known as Doppler VOR. Like below-

So always remember in flight we navigate with radial by keeping the needle in the center i.e coarse deviation indicator.