How do i fly a radial to / from VOR?

[janice]

I feel like a dope, and I'm sure this will be really difficult for someone to explain to me in a response, but here goes. . . .

I've been reading and looking at videos, but for some reason I can't twig to how to fly an angle to/from a VOR. For example, say my Nav 1 is tuned to 117.30 which is the GEP VOR in Minnesota. If I'm leaving airport KMIC, the VOR is at heading 349. So, let's say when I tune the OBS knob, I get 349 and set my heading to 349. What do I do if I want to fly 30 degrees away from the VOR to some destination I think is on the 30 degree radial once I fly over it? So, directly away from the airport on the GEP VOR is169, I think. Can I still track that on the CDI somehow, or do I just fly heading 139 (-30) or 199 (+30). Which one? How do I do that?

On another note (should be another post), I can't hear any Morse code signal on my Nav radios for any VOR stations in my A2A 172 - not sure why ...

Thank you in advance for directions - no pun intended ...

J

(Sorry - Canuck - had to edit cuz I did some math wrong.)

[AKar]

Hi J,

I'm not sure I understand exactly what you're after, but yes, VORs can be tracked both TO and FROM the station with no difference at all in technique.

In your example, if the station is at heading 349° from you, then you are on radial 349° TO the station. This is, of course, the same as radial 169° FROM the station. If you select 169° with your OBS, the only difference would be that the TO/FROM flag flips over to indicate that.

Typically it makes sense to select from those two the one that is similar to your situation: if you are flying towards the station, you'd generally want to track TO radial, and if you are flying away from the station, you'd like to track FROM radial. Note that if you overfly the station without any turn taking place, the 'switchover' happens automatically (well...let's not get into details! ). For instance, if I fly towards a station from the west, that is I'm on a radial 270° FROM the station as typically shown on charts, it makes sense to select the radial 090° TO the station. This way the flag shows the right way towards the station. When I fly over the station and continue eastbound, the flag flips over to indicate that I'm on the radial 090° FROM the station now! Because I'm now tracking outbound, the OBS is still set the correct way. Only if I wanted to turn around and return to the station, it would make sense to rotate the OBS 180° to indicate correctly that I'm now tracking radial 270° TO the station.

Not sure if this answered to your question?


Edit: The simplest way to understand VOR stations is to see how they are on maps. They sit at the center of a compass rose. Because in that picture, the radials extend out from the station, the compass headings shown around the station are equivalent to FROM radials. So if some place is located at given heading from the station, it sits on the radial of that heading FROM the station.

-Esa

[janice]

Hi Esa ... I understand the explanation you've written out. Thank you. Perhaps I'm misunderstanding something. Is it possible to fly only To / From a VOR station (or along that radial)? For example, if my destination is 30 degrees off to one side of the VOR station I'm tracking, can I fly directly to my destination using the VOR from where I am, or can I only get there (via VOR assistance) by flying over the VOR station, and then, eyeball the heading from the VOR station on a map, for instance, and turn to that heading and my destination?

J.

[AKar]

Ah now I see. No, that is not directly possible. Navigation that is not based on straightforward relationships with the ground based stations is called area navigation, and it typically uses aids such as inertial or GPS position determination.

Of course if one gets skilled with the needles and DME figures, one can cut the corners and fly more or less straight to the fixes determined by such relations, but in general, you have to find the radial and to follow it to the correct DME distance, or to appropriate intersection of two radials from different stations, whichever applies.

Of course you don't have to overfly the station itself, you can intercept the radial wherever you wish basically. In your example, I'd likely just cut the corner a bit, guestimating the interception of the outbound radial. But that wouldn't be real life IFR practice by any means!

-Esa

[Oracle427]

Janice,

That is why the direct to function on GPS is wonderful. Ground based radio navigation only allows for navigating to and from the station.

In your example above, why not dial in the new outbound course when you get near the VOR or overly it? You aren't limited in flying to the VOR, you can also use it to fly away from the VOR and to your destination. Just dial in a new radial at any time and fly a course to intercept it and off you go.



There is equipment that allows for functionality like GPS when using VORs, but I doubt anyone really uses that anymore.

[janice]

Hi Oracle. That's the language I'm confused about. You say dial in an outbound radial. I'm not sure what that means. Where would I dial that into? I suspect the answer is that I can only fly to / from a VOR, but if that's true, I'm not sure what your response means . . . I'm sure I'm misunderstanding something very simple / basic . . .

[Nick - A2A]

Hiya J,

VOR navigation is a really interesting subject and it's one of the first areas of fight simming I really took an interest in (back in FS5.1 days ). Rather than try and explain the whole TO / FROM thing in my own words, I thought I'd direct you to a website which is specifically aimed at teaching aerial navigation to flight simmers...

... Flight Simulator Navigation

It's written in a nicely accessible manner and I hope you'll find it helpful: there's a whole section on VOR navigation.

Cheers,
Nick

[CodyValkyrie]

Although you can use basic geometry to help with navigation, I'm cheating and using Skyvector to spit out the numbers. But, using this method you can get a general idea of how to navigate perhaps more efficiently.

In this first picture, we are flying from KUIL to the VOR TOU, then from there to 11S to land for a round trip of 39 miles. Not really efficient, and I'm always leery of flying directly over VORs where the airspace can get cramped.



In this picture below, we're saving ourselves about 17 miles by flying from KUIL directly to 11S, which is much more efficient. What I would do is take the radial from TOU to 11S in the first image, which is 77 degrees at 13 miles (approximately) and set my NAV1 to 77 degrees, giving me a radial from the VOR to 11S. Alternatively, I can set it to 258 degrees to give me the opposite radial course to the VOR (as shown on the map picture). Regardless, using my DME, I know if I fly roughly 006 degrees from KUIL to 11S, when my DME reads 13 miles, and my VOR is centered, I should be roughly over 11S. Naturally, I may need to make adjustments for wind, etc., but I can easily fly to or from the VOR radial to the specified distance (although there are more efficient ways). Either way, it's much more efficient and I don't have to fly to the VOR directly.

Of note, the ground speed noted on my DME will be off since I'm not flying directly to or from the VOR anymore.

One last matter is that since I'm using SkyVector, many of the numbers and radials are rounded rather than being entirely precise. You should notice that subtracting 180 degrees from 258 degrees doesn't give you 77 degrees (the opposite radial), but rather 78. This is due to the inherent nature of radials and the imprecise nature of navigation since we're typically rounding (especially on SkyVector). Remember, the further you get from a VOR, the less precise it is. This is where it pays off to double and triple check your information. For the purpose of this exercise, it should be precise enough to get us within a mile of our destination airport. More than enough fidelity for VFR navigation, as you should hopefully identify the airport at such a short distance (likely, you'll see it way before your NAV centers).

Anyways, give it a try in the simulator. It's an easy and fun flight. Unfortunately, GPS navigation is making VOR navigation entirely pedantic, and it seems less and less people know how to shoot ADF and VOR radials. It's a shame, because I find it not only more challenging and interesting, it also gives you a much better understanding of the fundamentals of geometry and how (and why) the navigation systems were set up in the first place.



Here is a wonderful interactive VOR simulator that is found freely online. I recommend you set up some virtual intercepts, etc., and play with the TO/FROM on the NAV gauge to get a feel for how it all works.
http://www.luizmonteiro.com/learning_vor_sim.aspx

As for the Morse signal, you need to turn on the associated NAV1 or NAV2 audio that you used to turn into the station (ie, if you tuned into the station with NAV1, then you need to turn on NAV1 audio). These are generally located on the audio control box above your COM and NAV radios. Once the signal is picked up, and the NAV audio is turned on, you will hear the identifier as found on your navigation charts. This is useful for ensuring you tuned into the right station, as well as helping you identify when the station is in range to receive a signal.

[Great Ozzie]

You say dial in an outbound radial. I'm not sure what that means. Where would I dial that into?

Into VOR Head 1. You would spin the OBS until 30° is at the top - if you are northeast of GEP VOR, then you would see a FROM flag.

What do I do if I want to fly 30 degrees away from the VOR to some destination I think is on the 30 degree radial once I fly over it?

It would be helpful if you said which airport, but here's an example based on what you are trying to do.

So you are departing KMIC, navigating off of GED VOR. Say you wanted to fly to KRNH (New Richmond Rgnl). Looking at skyvector for that area I see that KRNH lies along V78 (Victor 78) between STILS & AGUDE intersections. Victor 78 is defined by the 85° radial off of GED. STILS is 31DME and AGUDE is 42DME from GED (I'm cheating by using the enroute chart to get the distances).

So I have GED plugged into NAV1. OBS for VOR1 is set to 85°. I need a heading that will allow me to intercept that 85° radial off of GED... a 30° intercept angle will work fine... so I fly out of KMIC heading 55°. Needle is to the left (as it should be) with a FROM flag. When the needle starts to center up, turn to 85°. Keep the needle centered, and somewhere (about mid-way) between 31DME and 42DME I should find KRNH. No need (in this case) to fly directly to the GED VOR.

-Rob

[AKar]

Rob, this topic left me thinking, and I'm sure you've got some insight. This relates to similar situation I now see the original post was addressing.

Am I allowed to file and fly a plan like this for example with just VOR/DME/ADF equipment onboard? So, in this example, I'd be coming in V317 eastbound, but instead of overflying SSR, I've got a leg from RUKIE direct to PELTE, and then I'm proceeding on V428 southbound.

Of course, determining RUKIE is trivial, as it is just 12 DME to SSR, but the navigation on a leg from there to PELTE cannot be assessed by any means onboard.

Obviously, in the sim one can do anything, and that can be flown quite precisely, especially in VMC by eyeballing the Freshwater Bay 'behind' PELTE when looking from RUKIE, but assuming I'm filing an instrument plan, I'd think I had to have RNAV means onboard?

BTW, this is what makes flying VORs very fun in the sim! With GTN that would be just a trivial direct leg...

-Esa

[CodyValkyrie]

You'd be blown away at how little instrumentation is required for IFR flight.

§91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

...

(d) Instrument flight rules. For IFR flight, the following instruments and equipment are required:

(1) Instruments and equipment specified in paragraph (b) of this section, and, for night flight, instruments and equipment specified in paragraph (c) of this section.

(2) Two-way radio communication and navigation equipment suitable for the route to be flown.

(3) Gyroscopic rate-of-turn indicator, except on the following aircraft:

(i) Airplanes with a third attitude instrument system usable through flight attitudes of 360 degrees of pitch and roll and installed in accordance with the instrument requirements prescribed in §121.305(j) of this chapter; and

(ii) Rotorcraft with a third attitude instrument system usable through flight attitudes of ±80 degrees of pitch and ±120 degrees of roll and installed in accordance with §29.1303(g) of this chapter.

(4) Slip-skid indicator.

(5) Sensitive altimeter adjustable for barometric pressure.

(6) A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation.

(7) Generator or alternator of adequate capacity.

(8) Gyroscopic pitch and bank indicator (artificial horizon).

(9) Gyroscopic direction indicator (directional gyro or equivalent).

[janice]

All of the above is all excellent! Thanks to all of you. I have some projects to work on today, and I'm looking forward to it. I do have the basic VOR stuff down, and think I can get the rest figured out from all your work above.

Re. the Morse code radio signal: I am trying without success to hear the signal tuned into my Nav1 radio by activating the Nav1 button on the communication panel. I'll check again and make sure I haven't missed something. But it seemed to me it just wasn't working (to the point I even checked fuses). I'll let you know how I make out with that, and with the above.

And, I agree that it's a lot more interesting (and gratifying) to try to get around without GPS - well, except the other week when I was driving around Gabriola Island trying to find a friend's place while something was messing with the GPS in my car. That was just annoying!

Thank you again.

J

[Oracle427]

Right click on the Nav1 volume knob to pull it out and you should hear it.

[janice]

Got it. Had to right click on the Nav1 ident button (rather than vol). Had somehow turned it off.

[Great Ozzie]

Am I allowed to file and fly a plan like this for example with just VOR/DME/ADF equipment onboard? So, in this example, I'd be coming in V317 eastbound, but instead of overflying SSR, I've got a leg from RUKIE direct to PELTE, and then I'm proceeding on V428 southbound.

Well... the first thing is, you can file the route. But ATC decides what they will give you.

There's a couple considerations. As Cody posted, you need navigation equipment suitable for the route to be flown. That doesn't seem to be a great concern since you are so close to the SSR VOR and those two fixes very close off the VOR. A KNS80 would make that simple, particularly if the legs were longer, as that was one of its functions. That seems to be the real question here i.e. "how far off-airway am I allowed to navigate with just a VOR & DME". I don't really have a precise answer atm.

Communication and Obstacle clearance are concerns, of course. The highest MEA is 8000' (V593). You'll likely be @ 7000' or above. Lowest MOCA is 6000' (V428), so you still have Obstacle clearance (see §91.177). There is also §91.181 to consider - and this gives me a bit of pause when it comes to saying, "yeah... have at it". But at the same time, I don't see it contradicting the regs or the AIM.

You basically have a "straight arc" that you are flying. With the No.1 Nav, you can keep track of the course to be intercepted. With No.2, you can e.g. watch each 10° radial from SSR that you are crossing. And the DME, of course, lets you know where you are in relation to SSR & PELTE.

If part of your filed route was "RUKIE direct PELTE" and ATC comes back with a "cleared as filed," I am not aware of anything saying its not ok - and you save a couple minutes. Hope that helps.

Got it. Had to right click on the Nav1 ident button (rather than vol). Had somehow turned it off.

Right. That ident knob needs to be pulled out along with the NAV1 button on the audio panel. RW... sometimes you can get caught wondering, "why am not hearing anything" until you realize that the volume for that knob is turned down.

-Rob