vor question

[DaytonaLynn]

As a new ppl I have a question about VOR flying.

If you are not flying directly to a VOR, but it will be off to your right lets say. You enter your radial (from) that you expect to intercept.
What does the VOR indication do when you fly past the VOR. Will it flip to from to to?
I want to use this information as I fly from Houston to Daytona Beach.

Thanks for any suggestions or literature to read to help.
Lynn

 

[MAKG1]

What does the VOR indication do when you fly past the VOR. Will it flip to from to to?

Presuming you set the OBS to your course (or something within that hemisphere, at least), it will be the other way around. TO -> FROM as you pass. The needle will deflect full scale toward the station before that happens. How much before depends on how far away you are. If you have DME, its ground speed will show zero on station passage.

I strongly recommend against using radials ("FROM") for something you intend to intercept. Deviations will be backwards. They work fine if you're going to cross the radials and not intercept them. As you cross, the needle goes through center, but the FROM doesn't change. That occurs when the relative bearing is 90 deg.

 

[rbridges]

it won't flip unless you cross 90 degrees to the radial you're tracking. Also, Makg has a point. If you're heading toward a VOR, it's a good habit to have a TO heading. Not set in stone, but easier to avoid confusion.

 

[somorris]

Hi Lynn.

If you are flying as you indicated, your TO/FROM flag won't change. The CDI will be deflected to one side then as you pass the radial, it will start deflecting to the other side. If you have a FROM indication, the needle will be on the left side of center as you approach the radial, center when you cross, then deflect to the right side of center. The most assistance to navigation will be when it is centered. Then you location will be on the radial. Of course, the direction of CDI deflection will depend on which direction you are flying in relation to the radial.

 

[kkoran]

Playing with this VOR simulator might help you visualize what happens.
http://www.dauntless-soft.com/products/freebies/navsim/

 

[douglas393]

I may be analyzing this question too much. But in reality if you keep a steady deviation lets say a 2 degree deviation. As you get closer to the VOR that 2 degree deviation will represent a smaller actual distance from the radial so that at the time of passage you will essentially be flying over the VOR, and thus will exeprience the zone of confusion and the change from To to From or visa versa(I agree it is less confusing to fly to the VOR using the TO than the FROM). If on the other hand you use a constant distance from the VOR, your degrees of deviation will increase, presumably to off scale at the time of being on the radial 90 degrees to your chosen radial at which time the TO/FROM indicator will be in a zone of confusion and then switch to the other direction.


At least I believe this to be so. My question however is why keep a constant deviation of the radial instead of staying on the radial. I would think that would be less confusing.

Doug

 

[livitup]

Playing with this VOR simulator might help you visualize what happens.
http://www.dauntless-soft.com/products/freebies/navsim/

THANK YOU for this!

 

[Captain]

I read the question different. Like he's to the south east of a VOR, say 30 miles away on the 160 radial and wants to fly a heading of say 300 to intercept the 270 radial.

I'd say dial up the 270. It'll show 'To' until he crosses 90 degrees to it (180 radial) and then show 'From'. The whole time the needle will deflect to the right until it comes in as he settles on the 270 radial.

 

[DaytonaLynn]

Thanks everyone, I am going to go out and practice this over the weekend.

the link was a help.

 

[Kevin H.]

Don't need to make it too confusing... If you want to fly to a VOR twist the OBS until you get a TO indication with the needle pointing at the station. Fly that Heading.

For radials it's a bit different especially since you need to remember that the needle will point to that station no matter which way the plane is flying.

Let's say the VOR is on your right and you're flying 180 and wish to track the 090 Radial FROM the station. (Bearings are always To the station, Radials are always FROM the station). You will fly a heading of 180 and once lined up you will turn left to heading 090 to fly away from the station. If you want to fly TO the station you will turn right to 270 but will want to twist the OBS so that that it reads 270 and TO the station.

You can determine your relative position in relation to the position of the VOR by twisting the OBS until the needle lines up with a FROM indication. For easy reference let's say you are flying 360 degrees North and want to know where you are in relation to the Gorman VOR. Enter the Identifier for Gorman and twist the OBS needle until it lines up with the FROM indication showing. Let's say it reads 120 Degrees and 35nm on the DME. This means you are 35NM South East of the station on the 120 degree radial FROM the station even though you are flying north at 360. From this moment if you wanted to fly directly to the station you would simply turn left to 300 degrees to fly TO the station. It is always wise to set the CDI in the correct To and FROM aspect so if you fly directly to the station, set the OBS from 120 to 300 and verify the TO indication is reading. This makes wind correcting for your desired course to or from the station a lot easier.

It can be quite confusing but there are a lot of great videos on youtube that explain VOR navigation.

 

[gismo]

As a new ppl I have a question about VOR flying.

If you are not flying directly to a VOR, but it will be off to your right lets say. You enter your radial (from) that you expect to intercept.
What does the VOR indication do when you fly past the VOR. Will it flip to from to to?
I want to use this information as I fly from Houston to Daytona Beach.

Thanks for any suggestions or literature to read to help.
Lynn

It sounds like you're describing intercepting a radial when you haven't yet passed abeam the VOR. You do want to put the course you expect to fly after intercepting the radial. Don't worry about whether this results in a To or From indication that's just going to tell you if you've passed the VOR yet.

For example let's say you're southeast of the VOR heading due west (270) to intercept the 240° radial. You would set the OBS to 240 and you would see a "To" indication until you crossed the 150° radial (that will happen just before you pass abeam the VOR off your right wing). After crossing the 150° radial the flag will flip (slowly) to a "From" indication but the needle will be on the right side the whole time until you get centered on the 240° radial outbound from the VOR. If the flag hasn't flipped to "From" by the time the needle centers you've intercepted the 240° course (inbound on the 60° radial) before passing the VOR.

Keep in mind that aircraft heading (or more accurately course) has no effect on what you see on the CDI or To/From flag regardless of where you've set the OBS. What is affected by aircraft heading is whether the needle offset direction is towards or away from the course dialed into the OBS but that's simply because when you're course isn't in the same general direction as the OBS setting you've rotated the CDI (along with the rest of the airplane) such that the needle is pointing to the "wrong" side of the airplane.

Even though the texts on VOR operation will tell you that the "radials" run outward from the VOR, except when getting holding instructions from ATC (IFR stuff) it's common to call a VOR course a radial even when you are flying inbound on a course that's 180 degrees from the "radial" you are tracking (e.g. flying north towards a VOR on the 180° radial with the OBS set to 360).

 

[CBeaulieu]

Playing with this VOR simulator might help you visualize what happens.
http://www.dauntless-soft.com/products/freebies/navsim/

That's pretty cool!

 

[Bailey]

That's pretty cool!

I couldn't get the link to work in Internet Explorer but it did work in Google Chrome. Pretty simple but I could likely waste a shocking amount of time flying that little airplane around.

 

[somorris]

That's a pretty cool toy, Kent. Thanks for posting.

 

[gws]

Dear Miss Lynn, how did you get a PPL if you don't know basic VOR navigation? Work with a fellow pilot or your CFI and nail this, before you take your next trip anywhere!

 

[DaytonaLynn]

Dear Miss Lynn, how did you get a PPL if you don't know basic VOR navigation? Work with a fellow pilot or your CFI and nail this, before you take your next trip anywhere!

The plane I flew did not have it. It was in GPS and that's all I'd used. Now that I am in a 172/182 I am trying to learn how it works. On the GPS I used it was an little arrow to the station.

Make sense?

 

[DutchessFlier]

The plane I flew did not have it. It was in GPS and that's all I'd used. Now that I am in a 172/182 I am trying to learn how it works. On the GPS I used it was an little arrow to the station.

Make sense?

Oh my, Lynn, and I am not judging you at all, it does not make sense that you could not do basic VOR nav in that plane, but I don't know your setup. Get a friend, or CFI, who is familiar with the plane you're flying to go up with you and do some basic VOR nav till you feel comfortable.

 

[L.Adamson]

Dear Miss Lynn, how did you get a PPL if you don't know basic VOR navigation? Work with a fellow pilot or your CFI and nail this, before you take your next trip anywhere!

I don't know about getting the PPL...................but I haven't even considered VOR navigation for the last 18 years. And yes, I learned to fly before GPS was ever thought of. However, I wasn't about to waste money installing "out dated" Nav/comms in experimentals. I'm on my fifth Garmin aviation moving map GPS since 1994, and I can assure all of you, that my navigation "preciseness", and mental awareness of what's farther ahead (weather overlays) has never been better.

L.Adamson

 

[gws]

The plane I flew did not have it. It was in GPS and that's all I'd used. Now that I am in a 172/182 I am trying to learn how it works. On the GPS I used it was an little arrow to the station.

Make sense?

Forgive me. Yes, it does make sense now that you've said that you've never been introduced to VOR. However I can't believe that in your training that VOR navigation wasn't taught you until you were very familar with it. After all, it is still a very viable source of navigation and will continue to be so for a number of years to come. It has served pilots for many years as a safe and dependable source of navigation. If you want to depend on GPS for your primary source of navigation there's nothing wrong with that, but you still need to be proficient with a backup such as VOR in case of GPS failure. Hang in there. You're asking the right questions, but you need to ask them to your CFI or your examiner, not on the internet.

 

[JoeSelch]

Forgive me. Yes, it does make sense now that you've said that you've never been introduced to VOR. However I can't believe that in your training that VOR navigation wasn't taught you until you were very familar with it. After all, it is still a very viable source of navigation and will continue to be so for a number of years to come. It has served pilots for many years as a safe and dependable source of navigation. If you want to depend on GPS for your primary source of navigation there's nothing wrong with that, but you still need to be proficient with a backup such as VOR in case of GPS failure. Hang in there. You're asking the right questions, but you need to ask them to your CFI or your examiner, not on the internet.

Asking on the internet is what we do here at PoA.
Welcome to the board.

 

[turbo_jjr]

The VOR receiver and control head allows us to make or find
an electronic line in space.

The ground station is calibrated to transmit it's signals so
they are also mostly aligned with our compass directions.

The lines are often called radials, but have several other names
depending on usage.

When not strictly flying to or from a ground station, we might
pick a line (radial) for the purpose of knowing that we crossed
it.

The instrument would be centered when we crossed it.

But knowing only that we crossed it will not provide much definitive
navigation information. In this case the radial crossing would only
be supportive information.

For example, if I was flying a 360 degree course (no wind) and was out
over some rather non remarkable terrain. In other words it would be hard
to use pilotage to know where I was.

But I saw that during the flight I would be flying east of a VOR
station. On my map, I'd have a great big 360 course line drawn. Then
I add a 090 degree line off the the VOR station and see where it crossed
my 360 degree course. By setting my VOR to show me the 090 line, the needle
would center as I crossed it and I could see my location on the map.

It's old school to be sure, but getting a feel for it may help one day
when the magic goes dark.

 

[DaytonaLynn]

Thanks turbo that is jsut the answer I was looking for.
I wanted to go out and practice last week, but weather prevented

 

[L.Adamson]

It's old school to be sure, but getting a feel for it may help one day
when the magic goes dark.

I've completely understood the GPS system & it's advancements for almost 20 years. There is nothing mysterious or "magic" about it. BTW--- keep at least two boxes, just in case one does go dark.

 

[denverpilot]

The more complex a system, the more ways to take it down or have it fail...

 

[Fearless Tower]

BTW--- keep at least two boxes, just in case one does go dark.

While I agree that having two boxes is a good thing, what do you do to mitigate the possibility that one of the two boxes may be feeding you erroneous info? In other words, if you are in IMC and one box is providing the correct info and the other has say a loose antenna cable or other problem and starts providing an incorrect position, how do you determine which one is correct?

 

[gismo]

While I agree that having two boxes is a good thing, what do you do to mitigate the possibility that one of the two boxes may be feeding you erroneous info? In other words, if you are in IMC and one box is providing the correct info and the other has say a loose antenna cable or other problem and starts providing an incorrect position, how do you determine which one is correct?

Aside from spoofing (and spoofing pretty much has to target one single airplane) GPS, especiallyl WAAS has very high integrity meaning that if it gives a position solution, it's very, very likely to be correct within the design accuracy limits. VOR, not so much. So if I'm getting good status from the GPS I'm going to believe that if it conflicts with the VOR.

 

[tmyers]

I have two gps boxes. One in the panel and one on the yoke. Even with this I dial up vor's along my path for backup and practice. While doing so I log the airborne vor check in a book I keep in the plane for tracking vor accuracy.

 

[Fearless Tower]

Aside from spoofing (and spoofing pretty much has to target one single airplane) GPS, especiallyl WAAS has very high integrity meaning that if it gives a position solution, it's very, very likely to be correct within the design accuracy limits. VOR, not so much. So if I'm getting good status from the GPS I'm going to believe that if it conflicts with the VOR.

Yes, I understand that, but my question was not between GPS and VOR. It was when two different GPS units indicate two different positions (I have personally seen this in marine GPS applications). How do you know which one is correct?

 

[gismo]

Yes, I understand that, but my question was not between GPS and VOR. It was when two different GPS units indicate two different positions (I have personally seen this in marine GPS applications). How do you know which one is correct?

Easy. The one you paid more money for must be the correct one.

 

[douglas393]

Yes, I understand that, but my question was not between GPS and VOR. It was when two different GPS units indicate two different positions (I have personally seen this in marine GPS applications). How do you know which one is correct?

A number of thoughts here. Assuming this did not occur years ago I will avoid the discussion of the government purposefully making the GPS signal somewhat inaccurate. In my experience typically hand held units are less accurate than panel mounted units. In marine appilication there is DGPS which is more accurate than GPS so I would trust the DPGS. There are also WAAS marine units which are also more accurate than GPS. Also the mounting of the external antennae could be an issue. If the antenna are in the beam of the radar unit they will fail and give you a bad value. Finally, how far were they off, are we talking feet or miles. If miles I would think you have a bad unit and use other things to determine where you are, VOR, dead reckoning, ATC, etc. If just feet then would not worry too much. Maybe a product of where the antennae are.

Doug

 

[Fearless Tower]

A number of thoughts here. Assuming this did not occur years ago I will avoid the discussion of the government purposefully making the GPS signal somewhat inaccurate. In my experience typically hand held units are less accurate than panel mounted units. In marine appilication there is DGPS which is more accurate than GPS so I would trust the DPGS. There are also WAAS marine units which are also more accurate than GPS. Also the mounting of the external antennae could be an issue. If the antenna are in the beam of the radar unit they will fail and give you a bad value. Finally, how far were they off, are we talking feet or miles. If miles I would think you have a bad unit and use other things to determine where you are, VOR, dead reckoning, ATC, etc. If just feet then would not worry too much. Maybe a product of where the antennae are.

Doug

In the current case we are dealing with, I have seen the GPS posits to be as much as 1/4 to 1/2 nm off. With no indication of loss of signal. For enroute stuff, that isn't a big deal, but a 1/4 to 1/2 mile error in the approach phase could get you killed.

If you have two GPS units and a VOR, then you have a fully independent additional system to assist in determining which GPS is correct. But if you throw the independent system out (whether it is because of the govt or the operator getting rid of it) then how do you determine which one is correct and which is wrong if you find yourself in such a situation in IMC with no way to visually correlate? And for the sake of discussion, let's just say that both GPS units are top of the line, panel mounted.

If such a situation were to happen right now, in most places, you would at least have the ATC radar backup to assist you. What concerns me is that as we move toward Next Gen and ATC goes from using land based radar to relying on aircraft reported positions.....where is the backup? If I am mis-understanding the concept of NextGen, please clarify.

 

[douglas393]

In the current case we are dealing with, I have seen the GPS posits to be as much as 1/4 to 1/2 nm off. With no indication of loss of signal. For enroute stuff, that isn't a big deal, but a 1/4 to 1/2 mile error in the approach phase could get you killed.

If you have two GPS units and a VOR, then you have a fully independent additional system to assist in determining which GPS is correct. But if you throw the independent system out (whether it is because of the govt or the operator getting rid of it) then how do you determine which one is correct and which is wrong if you find yourself in such a situation in IMC with no way to visually correlate? And for the sake of discussion, let's just say that both GPS units are top of the line, panel mounted.

If such a situation were to happen right now, in most places, you would at least have the ATC radar backup to assist you. What concerns me is that as we move toward Next Gen and ATC goes from using land based radar to relying on aircraft reported positions.....where is the backup? If I am mis-understanding the concept of NextGen, please clarify.

Are they WAAS units or not. I only have a G1000 unit with WAAS and so have nothing to compare to it. I would certainly trust it over my 796 and IPAD. I agree with enroute it is probably not a big issue, though for some approaches and probably all approaches in the right conditions, ie at minimums, being off a half NM may be the difference between a successful approach and a NTSB report. I have always trusted my GPS and the only way I have been able to test it has been on VOR and ILS approaches where I had a ground based standard to compare the GPS line to the actual VOR or ILS heading, and it has been right on.

Has this really happened or is this an exercise in thinking?

Doug

 

[Fearless Tower]

Has this really happened or is this an exercise in thinking?

From a loss of GPS - yes it has happened. In the case we are currently dealing with the faulty GPS is a military GPS. Supposed to me more precise than the DGPS, but obviously our unit is having issues. Troubling part is that we get zero indication of the problem. Unit will show a Figure of Merit to indicate performance/signal quality (1 highest, most accurate and 9 is the worst). Our unit regulary shows a FOM 1 or 2, but position can be up to a half mile off the commercial GPS and this is confirmed by visual and radar fix. There have also been several maritime grounding cases involving faulty GPS receivers.

With that in mind, for the commercial aviation side, it is an exercise in thinking, and I think with Next Gen, it is a valid concern. Putting all eggs in one basket.

 

[douglas393]

From a loss of GPS - yes it has happened. In the case we are currently dealing with the faulty GPS is a military GPS. Supposed to me more precise than the DGPS, but obviously our unit is having issues. Troubling part is that we get zero indication of the problem. Unit will show a Figure of Merit to indicate performance/signal quality (1 highest, most accurate and 9 is the worst). Our unit regulary shows a FOM 1 or 2, but position can be up to a half mile off the commercial GPS and this is confirmed by visual and radar fix. There have also been several maritime grounding cases involving faulty GPS receivers.

With that in mind, for the commercial aviation side, it is an exercise in thinking, and I think with Next Gen, it is a valid concern. Putting all eggs in one basket.

No disagreement from me concerning Next Gen and VOR, but on another board I was shot down. As far as military versus commercial units, I have no clue why the difference should occur and you would think the military would be better.