Do I have this concept of VOR right?

[z.khalid]

Just a few questions to clear my mind.
I'm still training.

If the VOR is behind me, I will see a TO indication to the back and a FROM in the front on my HSI on the FPD?

When looking at an approach plate and I see R-120 for example, that would mean radial 120 that's the pulse coming OUT of the VOR is that correct?
Which if i'm flying TO the VOR would mean its track 300?

Also, what exactly is tracking, and homing to a VOR.
How is it done?

Thanks guys.

[skwinty]

Try this link.

VOR NAVIGATION (http://www.avsim.com/geoffschool/combined/vor.htm)

google is your friend :E

Take a chart, put it on a table.

Select 2 VOR stations and press a thumb tack nto the table at each location.

Take an elastic band and hook over the thumb tacks.

Now take one strand of the elastic band and strecth it to a third location.

This will be your aircraft location.

You will be able to read your radial from each VOR from the chart and the to-from indicator will be obvious.

The rule is "follow the needle". on the VOR receiver indicator.

[Exaviator]

The rule is "follow the needle". on the VOR receiver indicator. That was a good analogy skwinty, but I think that the last bit of advice maybe a bit clearer as follows:

The rule is "follow the pointer or head of the needle when tracking to the station, and the tail of the needle when tracking away from the station":ok:

[skwinty]

Thanks Exaviator.:ok:
The type of VOR indicator would be the general rule decider on whether you follow the needle or the head or tail of the needle.

Z.Khalid, here is an excellent and fully functional VOR program that should resolve any misconceptions.

VOR navigation system (http://www.pilotfriend.com/training/flight_training/nav/vor.htm)

[wangus]

Hi Z,
Years ago, I found VOR navigation bizarre in my first introduction, until it finally clicked in my head, and they're easy. I "think" I recognized a common misunderstanding / query in your question. (If not, sorry! Disregard)
If the VOR is behind you, you won't always get a from indication. It depends on what COURSE you have selected. If you are due North of a VOR station, and have 360 selected on CDI, you will have a FROM indication, as flying the selected course will take you FROM the VOR. If, with aircraft in the EXACT same position, you select 180 as your course, you would flip to a TO indication, even if you are in fact still flying NORTH. The flag would indicate TO the selected course, when you are flying further away from the VOR. (On the most basic equipment you may think you are flying towards station when you are in fact heading away from it, by accidentally selecting the RECIPROCAL course. Fly left / fly right indications are the opposite of what you actually want to do. Situational awareness is critical.)

What aircraft are you flying. Nav display?
Homing to a VOR, if you have an RMI, you literally point it at station, compensate for wind, and maintain that heading.
If you have an HSI, rotate the course selector thgrough 360 degrees until the bar centres itself with a TO (up) indication. Then select the same heading as the selected course, and keep the bar centered with small corrections, and you are homing to the VOR.

[Cloud Chaser]

I think you have the right idea, and some of the others have posted accurately,

(skwinty's first post describes how to fix your position using two VOR radials,
his second post refers to tracking and importantly refers to the difference between using an HSI or RMI type of display.)
(Exaviator's post about heads and tails relates only to the RMI type display, but it sounds like you are using the HSI style.)
(wangus was spot on)

I'll try to simplify

VOR Position Fixing

First get the idea of the beacon being in front of you or behind you out of your head. This is because aircraft heading is irrelevant, only aircraft position is important !!!

At every possible aircraft position, you can have the needle centered with the TO or FROM showing.

eg. Assume you are directly South of a beacon (the VOR is North of you).
If you centre the needle with TO showing the numbers will read 000.
If you centre the needle with FROM showing the numbers will read 180.
In this example you are on the 180 radial, radial always refers to FROM.

In the example above after setting the instrument up like this, if you now change your heading, even fly in a (tight) circle, the indication will not change, as it only relates to aircraft position.

So you now know you are somewhere on that line, but where exactly.
To get a fix you can either:
do the same thing with another VOR (what sqwinty described);
use a DME to get a distance from the VOR, the easiest option;
or use a NDB/ADF to get bearing from another beacon

This is VOR position fixing. (Remember the NDB/ADF works differently but since you only asked about the VOR, I won't confuse the issue taking about those.)

Supplementary information:

Tracking (homing is basically the same but that term would only be used if you are going towards the station, ie homing in on it, whereas tracking can refer to inbound or outbound).

Assuming we are talking about HSI displays.

First ensure it is set up correctly, meaning that you have selected the course you want to fly. This is also your desired track.
If not already on this course, you will need to intercept it.
Look whether the course deviation bar is to the left or right (relative to the head of the arrow) of your course.
This will give you an indication of the track you need to fly.
A tip is to look directly above the deviation bar (above assuming the arrow is pointing up), the number indicated here is a good rough indication of your intercept. (Intercepts will depend on distance form the VOR, crosswinds, etc but I will not go into that).
If you make that number your track, you will intercept that course, as the bar comes in, gradually change your track so it matches the number above the deviation bar, and you will find yourself on that track.
Now just follow the instrument to maintain, if the bar goes left, turn left to match, and vice versa.
:ok:

[MarkerInbound]

Tracking implies you fly a heading to maintain the desired "track." You're trying to fly outbound on the 090 radial with a north wind, so you end up flying heading 085.

Homing is mainly an RMI issue inbound to the station. You have a 0 degree relative bearing to the station. Say you tracked out to the 090 degree 40 mile fix and now you want to return to the station. You turn around and fly heading 270. Everything is centered up initially but the north wind pushes you south of course. Instead of correcting for the wind you turn just enough to center the RMI or on a VOR you set a new course to center the needle, say 280. Again you end up with the needle off to the right so again you center the needle and now you're going 290 to the station.

Tracking will give you a straight path to the station, homing will get you there but your actual path will be an arc across the ground.

[skwinty]

VOR navigation system (http://www.pilotfriend.com/training/flight_training/nav/vor.htm) See my previous post.

What is good about this simulation is that you can set the wind speed/direction, aircraft parameters speed/heading/rate of turn as well as setting the OBS.

You can also let the aircraft plot it's course over the ground as the simulation plays out.
This will illustrate all the points mentioned so far.

You must scroll to the bottom of the page to get to the simulation.:ok:

[z.khalid]

Firstly thank you all for the responses.

skwinty,
I just have a few concerns though.
I did not understand that the TO/FROM was a set thing, and the aircraft heading doesn't matter.

I get it now. It is always set the way it's shown on the diagram in the link?
But I don't get how that's relevant to us while flying.
Why do we care where the flag is TO or FROM.

I just am confused.

[skwinty]

z.khalid,

The TO-FROM indicator will indicate whether the VOR is behind you or in front of you when the nav receiver is set to the VOR frequency and the OBS dial matches your heading.

You can either fly a radial TOwards the VOR or a radial away FROM the VOR.

Let's say you are flying towards the VOR on a radial of 90 degrees, the needle is centred and the TO flag is visible.

You are now flying the 90 degree radial to the VOR.

As you get closer to the VOR the needle will behave in an erratic manner, however, when you pass over the VOR the FROM flag will be visible.

You will now be flying the 270 degree radial FROM the VOR.

Play with the simulator I linked to and you will get the hang of it.:ok:

[z.khalid]

Skwinty,

Thanks a lot again.
The simulator is definitely VERY useful.
Just one last question.
So I understand how the TO/FROM is relevant when our heading matches the OBS when we have the nav set to a certain VOR.
Say you were now on the same VOR that you talked about with a radial of 270 FROM the VOR.
Say on a SID it tells you to then track a radial of 030.
Now how is it relevant to us the TO/FROM flag?

Sorry for too many questions..

[Jetpipe.]

z.khalid,

Remember, the Radials ''radiate'' outwards from the VOR station and heading has nothing to do with TO/FROM indications..Everything comes down to position angle relatively VOR tracking Radial!

In the example above you say you have tracked and are on R270°. That would give a FROM indication. Meaning that since you are on the particular R270° your position is FROM the station VOR. Other positions that also would give you a FROM indication are all Radials ±90° from the R270° you are tracking. That is the range 180° - 360°. Theoretically, if your position would be R001° or R179° tracking R270° you would get a TO indication. I say theoretically because in real flight you would get something in between TO and FROM..

If you now try to intercept R030°, your position R270° would be outside the ±90° FROM range of the chosen R030° (range 300° - 120°), giving you a TO indication.

Hope that sorted things out,
Happy flyin,
Jp

[z.khalid]

Understood.
Thanks a lot!!! :ok:

[skwinty]

Great finish there Jetpipe.:ok:

z.khalid, only a pleasure to help.

ILS and Localiser back course just as easy.:ok: