TC and VORs - a story of love

[yvanddivans]

I just successfuly passed my PPL's written test but one question bugs me. It was something like...

Which radial should you take to head directly to a given VORTAC (with reference to VNC)?

[Lets say the aircraft is 20NM SE from the VOR]

1. 315; TO
2. 315; FROM
3. 135; TO
4. 135; FROM


... Assuming that only one anwser's good, I just don't know why/how, which of 1. or 4. should be better!?

Thanks!

[Edi]

3.

[StudentPilot]

Which radial should you take to head directly to a given VORTAC

You'd want to take the 135 degree radial because that`s where you are

Assuming you actually want to know what to set on the VOR, you have two options as you pointed out. 135 would give you a FROM flag, or 315 with a TO flag. The question is which is most correct, if you really wanted to you could track inbound with either.

The difference comes when you are not on the radial. Assume you are on the 120 radial. Set to 135, the VOR would indicate the 135 radial is to your right as if you were heading 135 degrees. If you set the VOR to 315, it would indicate the desired radial is to the left, as if you were heading 315. In this example if you selected 135 and flew 315 degrees inbound you would have reverse sensing. Just looking at the VOR needle, it would indicate the desired radial is to the right, even though that would take you farther away from the 135 radial. It would be better to set the VOR to 315, which would correctly show where the intended radial is, to reduce the chance of confusion and make your life easier.

[atpl53]

3.

Sorry Edi. You would only get that if you were in the North East quadrant.

[E-Flyer]

Just so that you understand VOR's a bit better.


Draw a fix on a piece of paper.

Draw a quadrant over the station

Then draw a bunch of straight lines leaving the STATION. These are your radials.

So if you are to draw the line (RADIAL) that heads SOUTH EAST bound, your only way to fly back to the station is to fly NORTHWEST Bound.



Think of the radials as lines that leave FROM the station. So anytime you want to fly OUTBOUND on a RADIAL, you need to have a centered needle and a FROM INDICATION.

"Air Canada 555, turn left 350 degrees to intercept RADIAL 315 outbound." I'm not an ATC... lol

If you want to how ever fly INBOUND on one of these radials, then you need to fly TOwards the station. Therefore you need a TO and a centered needle.

"Air Canada 666, turn right 090 degrees to intercept RADIAL 135 inbound."

So just to revisit your question, You are south east of a station and want to fly towards it.

South east is 135 degrees. So you are on RADIAL135. If you continue 135 you're just going to continue SOUTH EAST bound and won't get to your station.

If you fly the RECIPROCAL of 315 (135 + 180) you'll get to the station. But remember, since the VOR is a navaid that tells you where YOU ARE, you need to set up the OBS in the aircraft properly. So to get proper indications in this case, you need to set up 315 in the OBS and turn to the NORTHWEST and fly a centered needle.

Never confuse RADIALS with the HEADING you have to fly. This sums up what I said in the beginning of this post, RADIALS are lines that leave the station and travel away FROM the station.

So in the case of the transport exam, number 3 is right. You are on RADIAL135 as that's the line that leaves the VOR, and you want to fly TOwards it.

So how would you do this? Set OBS315, turn the heading to 315. If you were to cross the VOR and continue outbound with the OBS set to 315, you would now be on RADIAL315 flying OUTBOUND FROM the station.

Hope that helps

[Hedley]

Probably the simplest piece of advice that I can give
you about using the VOR is that your OBS head should
be set at the top to the track that you (eventually)
want to fly.

Let's say you want to track 320, either inbound or
outbound. Turn the VOR OBS knob to give you 320
on the top. If the needle is left, turn left. If the needle
is right, turn right.

When the needle centers, turn to 320 (zero wind)
and track the VOR radial, either inbound or outbound.

Most people use a 90 degree intercept inbound, and
a 45 degree intercept outbound, but these numbers
are not cast in stone.

Do keep in mind that the VOR needle in real life
will wander (signal "scalloping") and also that when
you get close to overhead the VOR, the needle will
go nuts, so just hold your heading that's been working
so far for you.

Here's a tip to REALLY help your VOR tracking in
the presence of wind. When the VOR needle centers
(back to our 320 example) immediately glance at
your GPS track-made-good, and immediately turn
so that your GPS track is 320. Magically, the needle
will stay centered, and the heading you are on will
perfectly compensate for the wind.

This is a good trick for LOC intercepts and tracking,
too, esp as you descend through wind shear which
is indicated by turbulence. After a while it will come
naturally - as you descend through the bumps, you
will instintively roll off some of your crab because
wind almost always decreases in strength as you
descend.

[iflyforpie]

You would set 315 TO on the OBS if you wanted to track to the VOR. 135 FROM would tell you where you are, but it would give you reverse sensing...(assuming a CDI and not HSI).

The RADIAL you are on would be 135 FROM and this (#4) would seem to be the most correct for the question asked, since all radials are FROM.

[Tim]

Let's say you want to track 320, either inbound or
outbound. Turn the VOR OBS knob to give you 320
on the top. If the needle is left, turn left. If the needle
is right, turn right.

thats not quite accurate. the intercept heading will be left of the desired intercept if the needle is left, but it's not necessarily a left turn to get to that heading.

[gustind]

The answer is 1.

[Tim]

The answer is 1.

you're mistaking the heading for the radial. he is SE of the VOR, which puts him on the 135 radial, he is tracking to the station. so he is tracking the 135 radial inbound by heading 315.

[Lurch]

OMFG I cannot believe this

With some of the answers given it's easy to understand why TC keeps asking these questions.

Because so many people still don't get it.

Lurch

[iflyforpie]

RTFQ^2

[CelBatrin]

Gonna jump in here CANNONBALL!

I would "take" (if that's the wording in the question) the 135 radial inbound. So 135 TO (#3).
However I would set the OBS to 315, and it should read TO. So based on that 315 TO (#1).

I think they're looking more for #1 though...

[TTJJ]

I just successfuly passed my PPL's written test but one question bugs me. It was something like...

Which radial should you take to head directly to a given VORTAC (with reference to VNC)?

[Lets say the aircraft is 20NM SE from the VOR]

1. 315; TO
2. 315; FROM
3. 135; TO
4. 135; FROM

The question, as written, is not the exact question from the exam. It has been paraphrased by the author.

...but one question bugs me. It was something like...

Given the difficulty in remembering questions from exams, coupled with the experience of the poster, ( I just successfuly passed my PPL's written test… Congratulations by the way. Welcome to aviation.), this is to be expected.

As written, “Which radial should you take to head directly to a given VORTAC…” the answer must be 4, as the question only asks WHICH radial you would “take” to the VORTAC.
We all know that radials are numbered clockwise outbound from the facility. The only radial given as SE from the station is 135.
In this case, as the aircraft is positioned SE of the VOR, a “TO” indication is not possible with 135 dialed in. The answer must be a “FROM”…135 FROM.

We also all know that we would select 315 TO in our VOR to fly this problem correctly. The question does not ask us how we would fly the solution, just what radial we would use.

If the question were “which VOR setting would you select to head directly to a given VORTAC..” , then number 1 satisfies the question and is how we in fact fly a VOR Radial.

As the question has been paraphrased and seemingly combined with the REAL options from the test, I feel that a definitive solution for the poster’s question as asked is impossible.

[Lurch]

Thank you TTJJ somebody finally got it, I didn't have the energy to explain and you did a better job even if I had.

Lurch

[Duncan Idaho]

Didn't read all the responses but I'll pitch in my pennies.

The 135's the only radial you can take from there. And you want to go TO it so you want a TO flag. So number 3, 135 TO is the answer. Here's the tricky part: You take the 135 radial TO the station by dialing 315 onto your VOR. But you're on the 135 regardless of whether you dial in 135 or 315 on your VOR.

[StudentPilot]

TTJJ explained the problem with the question very well (a lot better than my ).

This thread has got me thinking though - Is there a "135, FROM" radial? Or is it just the 135 degree radial and the question & answers provided are causing confusion or leading people to select one of the four answers? If no answers were provided, how many people would still say the correct response was 135, FROM (or TO) rather than simply the 135 degree radial?

I was taught you are on the 135 degree radial, or the 180, or 290 - note the lack of TO or FROM. The TO/FROM flag is part of the VOR head to help you fly inbound or outbound. In my neck of the woods most pilots report their position with respect to the local VOR - and always as "80 miles on the 175 degree radial" not "80 miles on the 175, FROM radial" or "80 miles on the 315, TO radial."

[North Shore]

Umm, Earth to Exam writers - I'd scroll through the VOR listings in my GPS database until I found the correct one, and then hit DIRECT and ENTER.... doesn't really help the OP, I realise...

[Lurch]

TTJJ explained the problem with the question very well (a lot better than my ).

This thread has got me thinking though - Is there a "135, FROM" radial? Or is it just the 135 degree radial and the question & answers provided are causing confusion or leading people to select one of the four answers? If no answers were provided, how many people would still say the correct response was 135, FROM (or TO) rather than simply the 135 degree radial?

I was taught you are on the 135 degree radial, or the 180, or 290 - note the lack of TO or FROM. The TO/FROM flag is part of the VOR head to help you fly inbound or outbound. In my neck of the woods most pilots report their position with respect to the local VOR - and always as "80 miles on the 175 degree radial" not "80 miles on the 175, FROM radial" or "80 miles on the 315, TO radial."

You were taught right

The original question, as stated by TTJJ, was obviously quoted wrong by the original poster. Causing a lot of confusion among the other posters.

Lurch

[yvanddivans]

Thanks everyone for your help!

I realise that my post might have been a bit confusing and my paraphrasing, misleading. The big problem I was having was chosing between two reciprocal radials (315:TO/ 135:FROM) which are "roughly" the same thing.

The choice of awnsers is exacly as in the test and that similarity got me confused and I just had to flip a coin. I chose 1-315;TO , since it seemed more logical to OBS my heading, and selecting radial 315 would display TO on the VOR, but I really wasn't sure of anything. Anyways! you guys where a great help in putting some light on all this!

Thanks again