Hi guys,

Wonder if I could get a little bit of guidance on how to answer this question:

"You departed Dubbo at 0327 for Mudgee. Your VOR [tuned to Dubbo] has 101 set on the OBS. Your DME is also tuned to Dubbo. At time 0336, the CDI on your VOR is indicating two dots left of centre and the DME is indicating 28. Your heading of 105 degrees M has been constant since departure.
At 0336, your ADF, tuned to Mudgee would be expected to read...?"

The track from Dubbo to Mudgee, as per ERC L 3 is 101 degrees

Cheers,

Dan

Hi Dan,
Sounds like you are 4° to the right of track given the VOR indications.
For working out the ADF reading, I like to start with what it would look like if I was on track first.

Using Bob's diagram, the track of 101° M and a heading of 105°M would show ADF needle pointing 356°R (assuming it's a fixed card type).
Now I work out the rest. From the VOR indication, the aeroplane is 4° to the right of track. This will cause the ADF needle to fall 4° away from what 'on track' looks like.
Falling a 4° away will give you the answer of ADF 352°R.

Just for the fun of it. Lets look at the same track and heading, but with the VOR 2 dots right of centre.
Going through the same process as before, we find the ADF pointing 356°R.
This time the aeroplane has been flown left of track. This will make the needle rise towards the top. Rising 4° will show the ADF pointing 000°R.

When you start using navaids the purpose for tracking, be it IFR, NVFR or VFR to aid visual navigation. It is important to always know the following-
What's my track?
What's my heading?
How many degrees difference is that and is it left or right of the nose?
and....
What should my navaids look like (indicate) when I'm on track?

From this, you will easily know-
When you are off track.
How far you are off track.
and....
How quick did it go off track. Good to know for working out how windy it really is or isn't.

If you are a bit confused about what I mean with head rising or falling . Please read my post on the 'ADF Fixed card' thread.
www.bobtait.com.au/forum/navigation/4101-fixed-card-adf

Hope this helps.

Cheers,
Mister W.

Hey Mister W,

Thanks a lot for your reply. It has helped a lot. I am going to bug you for more, now! I am going through the practice IREX questions on the CASA website (great resource for those who don't know www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90060) and since they don't have answers I'd just like some confirmation, if that's okay?

An aircraft tracks out from overhead an NDB on a constant heading.
Planned track ....... 030(M)
Heading ............... 040(M)
Backbearing ........ 185 Relative.
What is the track error (in degrees)

First, establish the TMG which is H +- A = T
040 + 5 = 045 degree TMG

Then establish the track error by drawing a diagram with the Flight Planned Track across the page and placing the TMG either left or right of that line. In this case it is greater, therefore the track error is 15 degree right? How have I done?

There will be more, if that's okay?

Spot on, mate!
And, If it was on track, the ADF would read 170°R. Therefore ADF 185°R would be 15 ° off track.

Good work. Glad I could help.

Cheers,
Mister W.

And another one! A little different this time.

An aircraft situated to the south-east of an NDB is flying in a westward direction. If the aircraft is maintaining a track of 270M by allowing for 10 degrees right drift, what is the relative bearing that would indicate the aircraft is positioned south of the station?

By working out the heading, using the drift diagram, I established it to be 260 degrees. Therefore as the aircraft will be facing left of 'on track' and in my mind using the piece of string attached from the ADF needle to the station, the ADF relative bearing would read 100 degrees when directly south of the station?

I do believe you have it!
Good work, Dan.

Cheers,
Mister W.

Mister W, thanks again for your time! I really appreciate it. I have booked my IREX exam for a couple of weeks and am trying to smash out as many practice questions as possible!

You are tracking from a VOR station on a HDG of 060 and the VOR OBS is selected to your desired track of 054. The CDI is indicating 3 DOTS to the RIGHT. The flag is showing FROM, and the DME in the aircraft is reading 20. The distance off track is closest to:
A. 2 nm left
B. 2 nm right
C. 6 nm left
D. 6 nm right

To me, this seemed like a 1-in-60 question, whose formula is d x 60 / D where d is the distance off track and D is the distance flown, and since we want to establish the distance off track I substituted the answer in the formula to see if it matched the degrees off CDI centre:
d x 60 / D
2nm x 60 / 20 = 6
Since the CDI is 3 dots (6 degrees) off to the right, and this matches the answer I got numerically I would say the answer is 2 nm left of track?

That's sounds about right. They throw the heading of 054 into the question as a bit of a curve ball as a distraction.

Cheers,
Mr. W

Thanks! This one I don't actually know how to answer:

You are on a track of 040 degrees which passes some distance to the left of a VOR station. The HDG you are steering is allowing for 10 degrees left drift. When you are abeam the station, if you centre the CDI and have the flag showing TO, what would the OBS be dialed to?

Also, just confirming what happens on station passage with a VOR... As far as I know there are no visual indications, however assuming no change to the OBS the only difference will be that it is no longer in a command sense?

This one is actually not as hard as it sounds. Anything you pass abeam of is going to be at 90 degrees of your track.
So, if your track is 040. You are flying to the left of the VOR station (imagine it directly in front then turn to the left of it). 90 degrees around from 040 will give you......??

Apply the same question but using an ADF and see what you get!


Cheers
Mister W.