Here is an example of how to use 'triangulation' to get to an airport that has no VOR on the field. With this method you can get anywhere you want to, as long as there are two VORs that you can tune into. You simply decide where you want to go to and then you figure which radials of which two VORs will intersect (cross) above your destination. Triangulation works best if the radials are perpendicular to each other but it's not mandatory. It just makes it a bit easier to find your destination.

In this tutorial I am going to use the Maule. I will add some extra information here and there (in italics) that may be a bit too advanced already for this tutorial or that may need some more explanation, so if you don't understand some sidenotes, just ask and I will explain it in greater detail. Or simply skip the italic parts.

 

I want to fly from HI27 to HI05, a very short flight for which I advice you to take the car in real life, but since this is an example which enables me to show the basics of this method in an easy way (because we won't be needing reciprocals and the radial to intercept is nearby), we'll go by plane anyway. If you want to try it all yourself, use the Clear skies weather theme to not make it more difficult than needed.

 

 

To figure out how to get to HI05 you officially should have a map of Hawaii with all VORs on it and then draw lines from the VORs to your destination to figure out which radials from which VORs intersect above HI05. However, I used an easier method... I simply went to http://www.airnav.com/airports/, entered 'HI05' in the Search field and on the next page, http://www.airnav.com/airport/HI05, I scrolled down to 'Nearby Radio Navigation Aids'. It shows four VORs and the radials that run over and hence intersect at HI05. (It also shows the distances from the airport to the VOR, but we won't be using these because you won't always know those exactly and it spoils the fun of triangulation.)

 

 

After looking at the map of Hawaii I decided to use the HILO and KAMUELA VORs because, as I said, triangulation works best when radials are perpendicular to each other. (I also could have used UPOLU POINT but that would make this example a bit more complicated because I would be flying towards that VOR and so I would have to use the reciprocal of the radials... which is something for another tutorial.) For your convenince I drew the radials on the map so you can get a better idea of what we are going to do. Normally I only paint a mental picture of the situation.

I situated myself on the SW runway of HI27. After take off I will probably be able to start intercepting the 297 HILO VOR radial outbound towards HI05 right away since the radial almost runs over HI27. When we proceed to fly on that radial we will at one time cross the 050 radial of the KAMUELA VOR and that's when we know we have arrived at our destination.

Obviously it's very helpful to plan your flight in advance and figure out what you need to do: if you don't do that you may get lost pretty easily. If you for instance have not figured out in advance where the VORs you are going to use actually are in relation to your plane, you might be heading in the wrong direction before you know it!

 

 

Let's first show you where all the instruments are which you are going to need.

Use the outer- and inner rings to set the standby frequency and then click on the switch button to make it the active one. When the VOR is active you can click on the IDENT button to hear the morse code of the VOR and check if you are actually receiving the signal of the right VOR.

The OBS knob is used to set the radial you want to work with.

The TO/FROM indicator shows you if you are flying away or towards the station (but always in relation to and depending on the radial you set up! You may be flying towards a VOR station even when the TO/FROM shows TO).

The Deviation Bar (on the HSI) or the CDI (on a regular VOR gauge like VOR2 in the Maule) shows you if the radial is on your right or left (depending on the radial you use and the heading of your aircraft! If the heading of your aircraft is more or less in the same direction as the radial, a left deflection of the CDI means you need to move left to intercept the radial and a right deflection of the CDI means you need to move right to intercept the radial).

 

 

Here I am at the SW runway of HI27. As I said I am going to intercept and fly outbound on the HILO radial so I will use NAV 1 (and hence the HSI) for that one. I always use NAV1 for the radial I am going to fly on. The other radial will ONLY be used to show me when I have arrived at my destination, so I will use NAV2 (and hence VOR2) for that one. When using triangulation I find it easier and more convenient to pick one radial to intercept and fly on and then use the other one only to show me when I have arrived at my destination. It saves time and fuel etc. when you try to fly to the intersection in a straight as possible line, but that's a bit harder to do.

As you can see I already tuned the radio's here and I also turned the OBS knobs to the radials I want to work with. VOR 2 is already active (since it is rather close): VOR 1 (on the HSI) isn't yet but it probably (and hopefully) will be as soon as we have taken off.

 

 

Shortly after take off VOR1 becomes active. The Course Selector Pointer and Deviation Bar on the HSI show I can already begin to turn right to intercept radial 297, just as I expected. (On the DME, the instrument underneath the NAV 2 radio) you can see the distance to the VOR and the speed at which we are moving (in this case) away from it.) The TO/FROM indicator shows FROM as it should when you fly outbound on a radial. (The VOR2 also shows FROM even though we are flying towards it (see the map with radials above), but that's because we are using the 050 radial. Because we are not planning on flying towards the radial but only use it to check if we reached our destination, that's fine. If we wanted to actually fly towards the KAMUELA VOR on radial 050, we would have to use the reciprocal of that radial, which is 230: if we would turn the OBS knob until it shows 230 at the top, then the TO/FROM indicator would show TO. But let's not make things too complicated for now... )

 

 

Here you can see me flying on the 297 radial (check the HSI). VOR2 is still deflected fully left. Now all I need to do is keep on flying on the 297 radial until the VOR2 CDI starts to move!

 

 

There it goes! I am getting close to my destination! As soon as VOR2 is centered (and if I can keep VOR1 centered too) I should be above HI05.

 

 

VOR 2 is almost centered now and I can clearly see my destination in front of me! I can forget about the VORs now and simply fly around the airport to make a good approach. Some airstrips are hard to find and you won't notice them until you are above them: obviously if you had seen the airport earlier on, you could have setup your approach already, but it's too late for landing now on this short distance, so I will fly on...

 

 

...until I am straight above my destination. As you can see the VOR2 CDI is centered now but I have lost contact with the HILO VOR: it's some 32 nm away and I am flying too low now to keep contact with it. Obviously this is no problem right now. If you however haven't had a visual on your destination yet and you lost contact with one of the VORs, you might need to fly a bit higher to get contact again!

 

 

Well, this was just one simple and basic example of using VORs and triangulation to get you to a spot that has no VORs itself.

 

If you have questions about something I've posted (some of the italic stuff maybe) or even if NOTHING makes sense (or if I made a mistake somewhere), just ask!

Some additional information about TO and FROM and how you the VOR gauge can show FROM while you are flying towards it.

 

The TO/FROM indicator is always related to and completely dependant on the radial you are using. Imagine you are standing in front of the VOR station. You walk around it and you stop on the 050 radial. Turn your back to the station so you are looking straight out over the (invisible) 050 radial. Spread out your arms left and right so they are perpendicular to the 050 radial: your arms are now on the so called 'line of ambiguity' which divides the VOR circle of 360 degrees in half. Everything that is in front of you, all 180 radials, are on the FROM side. Everything that is behind you, all other 180 radials, are on the TO side.

 

Since you are standing on the 050 radial this means that the radials 320 to 140 are all on the FROM side and all other radials are on the TO side. All 90 radials on the left of 050 and all 90 radials on the right of 050 are on the FROM side. All other 180 radials are on the TO side.

 

In my tutorial I was flying east of the KAMUELA VOR. I had the VOR set to 050. I was flying towards the VOR but the TO/FROM indicator showed FROM simply because... I was on the FROM side! I was flying on a radial somewhere between 320 and 140.

 

Knowing where you are (situational awareness) is very important during flying. Simply checking the TO/FROM indicator can give you an quick idea of where you are in relation to the VOR. When you are flying somewhere and you see TO go to FROM, you know you have passed that 'line of ambiguity' and you were on the radial +90 or -90 of the radial you set on your VOR gauge.

Imagine again you have set up radial 050 and your heading also is 050 but you are not flying straight to the VOR (you are simply flying parallel to the 050 radial). You see TO on the gauge and you know (no matter how, you just do for this example ) that the station is somewhere to your left side. Suddenly TO changes to FROM. When that happened you passed the (50 + 90 =) 140 radial. Without having to turn the OBS knob you knew exactly where you are at that moment.

 

Because I quite often have problems figuring out mentally where I am in relation to a VOR (also because HSI or heading indicator constantly turns making it hard to use that for reference) I made a circle showing 36 radials which various lines that make it easy to see where I am but also what's the reciprocal of a certain radial and where the line of ambiguity is (and hence when I should see TO going to FROM). I printed it and have it lying on my desktop when I fly. Whenever I want to know where I am in relation to a VOR I figure out on which radial I am, look at that print and I have a clear visual view on my position in the virtual world.

 

Here is a jpg of that circle for printing:

 

 

And here is the same circle showing my example with the 050 radial. The green 'thing' is you , the red line is the radial you set (050), your arms are on the line of ambiguity, perpendicular to the used radial, cutting the circle in half. When you are anywhere on the red side the VOR gauge will show FROM, no matter where you are heading and when you are anywhere on the blue side the VOR gauge will show TO, no matter where you are heading.

 

Nice write-up! The pics inspired me to make one illustrating the flight I mentioned earlier, hopping around the Big Island via three VOR stations. It used some of the same techniques, although my destination did have a VOR on the field so I didn't have to find it via triangulation. I'll have to summarize it below, since I can't go back and Edit this in now...

 

I did a Job from one of the dinky little strips on the south side of the Big Island, flying the Kona 130 radial to intercept the Upolu 170 radial at 9000' (arcing around Mauna Loa), IFR conditions all the way, flying over the top of Puu Hualalai, waiting for the peak to loom out of the clouds right in front of me, then descending to 4000' while intercepting the Kamuela 220 radial, leading me right to a straight-in approach into Waimea-Kohala.

 

That is an awesome contribution to the Flight community. Thank you my friend :)

 

That was meant for J, but thanks to you too RR :)

Two thumbs up for this thread. It is the best that I have seen on this forum. Hats off to all who have contributed.

Next step for Jeroen, using one VOR and a clock to identify the plane's position and then navigating from there. :Nerd:

Thanks for this very helpful thread. It gets pretty depressing wading through all the negativity elsewhere on this board. Threads like this one are why I signed up with AVSIM.

I did a Job from one of the dinky little strips on the south side of the Big Island, flying the Kona 130 radial to intercept the Upolu 170 radial at 9000' (arcing around Mauna Loa), IFR conditions all the way, flying over the top of Puu Hualalai, waiting for the peak to loom out of the clouds right in front of me, then descending to 4000' while intercepting the Kamuela 220 radial, leading me right to a straight-in approach into Waimea-Kohala.

 

Great flight! I think I am going to do this exact one tomorrow (making sure I fly high enough... ).

 

Without having to add screenshots I'd like to use your flight (if you don't mind ) for something I mentioned in my previous tutorial but didn't fully explain.

 

(In this example I will be talking about regular VOR guages btw, as in the RV-6A and the VOR2 in the Maule, so not about the HSI. However, the same rules apply to the HSI, but the advantage of that one is that it doesn't give you reverse sensing, which I will explain below.)

 

The VOR is usually used as a commanding instrument: you set it up in such a way that you follow its commands. When the CDI is left of the center it means you are right of the radial so you simply move left to get (back) to the radial and when the CDI is right of the center it means you are left of the radial so you simply move right. You do as the instrument commands you to: you follow the CDI. To not make it too complicated I made sure the radial I was flying on in the tutorial was outbound of the station: this way all I had to do was turn the OBS to the radial number and fly that heading with the TO/FROM indicator on FROM.

 

Now imagine someone who read my tutorial would like to fly RoboRay's flight. He would take off, turn the OBS to the KONA 130 radial and... he would get completely lost! Why? Because he would try to follow the CDI... but when you fly inbound ON a radial, the left-right commands are reversed! In RoboRay's flight, as you can see on RoboRay's picture, every radial you fly on has to be flown TOWARDS the VOR station. So inbound instead of outbound. Flying with the VOR showing the opposite command is called 'reverse sensing' and it should be avoided if possible!

 

So here are three (new) rules:

 

1. when you fly inbound on a radial, use the reciprocal, which is the opposite of the radial you are flying on

 

2.in order to use the VOR as a command instrument, make sure your heading is in the same general direction as what the top of the VOR gauge shows

 

3. when you fly towards a VOR on the desired radial, you want the TO/FROM indicator to show TO and when you fly away from a VOR on the desired radial, you want the TO/FROM indicator to show FROM.

 

So, in RoboRay's flight the first radial you have to fly ON (not 'to' but 'on' and inbound) is the KONA 130 radial. SInce you have to fly it inbound, use the reciprocal which is 130 plus or minus 180. So that would be 310! Use the OBS knob to set the VOR gauge to 310 and follow the instruments to intercept that heading. You will see that you will be able to fly left when the gauge tells you you need to go left and the other way around. So rule 1 has been applied. You will also see that when you have intercepted the radial your heading will match what the top of the VOR gauge shows you: 310. Rule 2 has been applied. And you will also see TO activated. Rule 3 has been applied.

 

While you are flying towards Kona (or even better already on the ground before take off) tune NAV2 to UPOLO POINT. You should intercept radial 170 inbound, so 170 plus 180 is... 350! Use the VOR2 OBS knob to set the instument to 350.

 

Now simply fly on on the KONA 130 radial (using the reciprocal) and at a certain moment, no doubt about it, the VOR2 needle will start to center. When it is almost centered turn to a heading of 350 and intercept the UPOLO POINT radial. You are now ON the UPOLO POINT 170 radial and navigating with the use of the reciprocal. You will also see TO activated.

 

Repeat this procedure for the last leg of the flight. You can keep on flying using VOR2 and while you do so set NAV 1 to the KAMUELA VOR. You need to intercept the 220 radial inbound, so... calculate the reciprocal and that's... 040! Use the OBS knob to set 040 and after a while, the CDI will centre and you will hit the 220 radial. Turn right to intercept it using the reciprocal of 040. Use that settings to get you all the way to Waimea-Kohala.

 

So when you fly inbound to a station, use the reciprocal of the radial you are flying on. When you fly outbound, use the radial itself.

 

Having trouble calculating the reciprocal?

1. Add 200 and subtract 20

or

2. Subtract 200 and add 20

 

Example 1: you need to fly the 60 radial inbound: (60 + 200 = 260) - 20 = 240

Example 2: you need to fly the 310 radial inbound: (310 - 200 = 110) = 20 = 130

 

About flying on a radial

As I said radials always and only go outbound of a VOR station. So you can only fly on the 180 radial south of the station. You can't fly on the 180 radial north of the station. So that's why RoboRay said you have to intercept the 170 radial to the UPOLO POINT VOR and not the 350 radial (which is the reciprocal). Even though you actually fly a heading of 350 and hence sort of use the 350 radial of the VOR, you are ON the 170 radial all the way and that is the one you intercept!

When you fly using VOR you always refer to the radials you have to be on or you have to intercept: the pilot him- or herself has to determine if he or she needs to use the reciprocal or not!

Great flight! I think I am going to do this exact one tomorrow (making sure I fly high enough... ).

 

Without having to add screenshots I'd like to use your flight (if you don't mind ) for something I mentioned in my previous tutorial but didn't fully explain.

 

Oh, by all means, please do!

 

For the record, yes, I did have the reciprocal radial dialed in for Upolu on NAV2. I always get mixed up when I try to use reverse sensing... it's just easier to spin the OBS all the way around. I had Kona and Kamuela on NAV1, using the HSI.

 

I just thought of a suggestion for the Dev Team, too... The tool-tip for the OBS knob shows the bearing you are dialing. It sure would be handy if it showed both the bearing and the reciprocal.

 

I also just noticed something about the sectional I used for the picture... it's too new!

 

Flight uses the old Kona VOR (IAI) on 115.7 MHz, down by the old, now closed, Kona airport. The station is actually shown on the image above, but the frequency info is crossed out as (I assume) it's decommissioned. This sectional shows the compass circle for the new Kona VOR (KOA) on 112.1 MHz at the new Kona airport.

 

My old paper sectional from 2002 has the new Kona airport, but not the new Kona VOR (that does not function in flight, as I tried tuning 112.1 at Kona to test). The compass circle is drawn around the old Kona VOR on my chart, so the actual flight path for my first leg was a little south of the line on the image. You may want to keep this in mind if you try the flight in IFR conditions at ground-hugging altitude, as Moana Loa slopes up to the right of the flight-path.

 

I showed the corrected path for the first leg in green...

 

 

When I first drew the lines in, I was wondering why it took me so long to get turned to the proper course after my take-off to the north-east.

 

I guess I win for not throwing out expired charts!

You can buy this iphone or ipad app and learn too

 

http://www.digitalaviation.com/

 

-------------------------------------------------------------------------------------------------------------------------

 

This is the best website IMO to learn everything about flight, VOR, NDB, IFR ILS etc etc

 

http://www.navfltsm....com/vor-nav.htm

 

This is what got me to enjoy simming and then got me to learn to fly for real.

Fantastic thread. Thanks for your hard work! Certainly worthy of a "sticky" from an admin.

This is the best website IMO to learn everything about flight, VOR, NDB, IFR ILS etc etc

 

http://www.navfltsm....com/vor-nav.htm

 

Agreed. That's why I posted that exact same link in my openingspost already.

This site has a lot of useful information, including online VOR simulators:

 

http://www.luizmonteiro.com/

This site has a lot of useful information, including online VOR simulators:

 

http://www.luizmonteiro.com/

 

Yes, indeed a great site! Should have added that VOR simulator to my OP! "TheVOR (VHF Omnidirectional Range) Simulator was designed to demonstrate the approximate indication that a VOR would display with varying positions of an aircraft in relation to certain navigational facilities." Very good simulator to learn how to read the gauges and actually see how for instance TO and FROM work..

 

I have to add though that I heard before there is a lot of useful information on the site but I only see simulators and calculators... I was never able to find that 'useful information', for instance about VOR. Am I missing something obvious?

Agreed. That's why I posted that exact same link in my openingspost already.

 

But I wanted the credit!

 

Tsk Tsk! :Nerd:

 

Manny