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IREX (May 2015) Ex10 Q15

  • Migraine
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Migraine created the topic: IREX (May 2015) Ex10 Q15

Hi Bob/Rich,

I was doing OK until I hit this particular question. :/

I came up with 205°M as my answer but the book answer is 295°M. Can you please shed some light on where I've gone wrong?

Please see attached my workings out.

Many thanks,

:)

Black Line: A/C HDG 290°
Blue Line: ADF 330°Relative
Red Line: = 250° ADF track inbound
Green Line: = 45° Intercept (of the 250° ADF track inbound)

File Attachment:

File Name: IREXQ15PAGE47.pdf
File Size:814 KB

File Attachment:

File Name: IREXQ15PAGE47.pdf
File Size:814 KB

File Attachment:

File Name: IREXQ15PAG...0-27.pdf
File Size:814 KB

File Attachment:

File Name: IREXQ15PAG...27-2.pdf
File Size:814 KB

File Attachment:

File Name: IREXQ15PAG...27-2.pdf
File Size:814 KB

250° - 45° = 205° HDG Intercept
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  • John.Heddles
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John.Heddles replied the topic: IREX (May 2015) Ex10 Q15

I don't have Bob's material to look at so I am a bit lost with what your links are trying to say .... not all that sure how you have gone about solving this problem

However, you don't appear to have done the necessary orientation figuring in the first instance to get a starting point ... suggest you go back to Link Trainer basics to nut out the problem ..

(a) where am I ?

(b) where would I like to be ?

(c) what's the most efficient way to get to (b) from (a) ?


My figuring in the box (while drinking the obligatory cup of coffee just handed in by the Link instructor and engaging him in irrelevant discussion - his task is always to add a bit to the workload) would be ..


(a) HDG = 290M

ADF = 330R

if I were to turn left 30 deg the ADF would show 000R (I am pointing to the station) and the DG 260M (I am somewhere on the 080M bearing from the station)

(b) if I want to track 250M into the station then I need to be somewhere along the 070M bearing from the station. That bearing (070M) is north of my present position (080M).

(c) quickest way to get to a position north of my present position is to head generally north .. which makes 290M as good a starting strategy as any (the station is out to the left somewhere so 290M is probably going to give me a good track mile starting solution .. certainly better than turning to a more northerly heading for only a 10 degree change in bearing) .. so I'll maintain that for a bit while I figure out the final details.

for a 45 deg intercept onto the 070M bearing I will need to pick up a heading of 250 + 45 = 295M.

when the ADF gets to 315R I will be on the 070M bearing from the station .. just need to anticipate that a bit with just enough lead to allow for the turn onto the required bearing from the station and Bob's your uncle.


What I see during the exercise is .. the actual starting numbers will depend on how quick you are with the head scratching and number crunching ..

- initially, I turn right from 290M to 295M

- ADF changes from 330R to 325R

- from whatever I had been doing (and this isn't in the question) I will have an idea of what the wind might be and how far I might be from the station .. so I will need to factor those considerations into the actual geometric situational solution to make sure I don't inadvertently fly through the bearing or do something equally unhelpful ...

- as I fly merrily along on 295M the ADF needle falls away to the left progressively moving towards 315R

- a bit before the ADF gets to 315R (how much depends on speed and my prior assessment of wind and distance out), I allow a suitable amount of lead and commence a turn to the left to pick up the 070M bearing, allowing a suitable HDG delta for my guess at the wind and then refine that drift angle as I track inbound to the station.

Easy peasy .. now, I haven't played with fixed card for, probably, 25 years .. so I would be just as slow as you in the box. However, once you do a few of these, it doesn't even take any real mental effort .. you just look at the DG/ADF and the picture changes magically in your head to come up with the answers in a second or two. I cannot emphasise enough the importance of complete and accurate orientation .. that is the basis of most navigation solutions .. if you don't know where you are to the best accuracy available with the data at hand .. how can you figure out how to get to where you want to be, other than by playing pin the tail on the donkey ?

Using an RMI, of course, is cheating .. at least to us old chaps ... and, as for using the Map page ... well, that qualifies for Children of the Magenta Line membership ...

Engineering specialist in aircraft performance and weight control.
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bobtait replied the topic: IREX (May 2015) Ex10 Q15

Using the "HAT trick" the present track to the station is H (290) + A (-30to) = T (260° to the station)
The required track is 250° to the station.
You are left of the required track.
Heading to use is 45° to the right of the required track = 295°

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  • John.Heddles
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John.Heddles replied the topic: IREX (May 2015) Ex10 Q15

Now you have me scratching my head somewhat.

The links given in the first post appear to indicate that the present data is 300M and 330R - reference the two graphics immediately under the answer alternatives.

I note that I don't have the benefit of the book to review so perhaps it may be that I don't have all the data for the question ... but how can 300M/330R suddenly become a heading of 290M and a bearing to the station of 260M ?

Engineering specialist in aircraft performance and weight control.
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  • Migraine
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Migraine replied the topic: IREX (May 2015) Ex10 Q15

Dear John,

My apologies.

The original post had an error regarding the DG. It should have read 290°M, and not 300°M. I'll try and add a corrected attachment.

Sorry for the confusion :/
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  • Migraine
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Migraine replied the topic: IREX (May 2015) Ex10 Q15

Amended diagram

File Attachment:

File Name: IREXQ15PAG...0-29.pdf
File Size:785 KB
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  • John.Heddles
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John.Heddles replied the topic: IREX (May 2015) Ex10 Q15

Ah, thanks for that, good sir. Earlier post updated appropriately (hopefully, I spotted all the bits which needed consequential changes).

I am quite convinced, though, that your initial problem was not having a good enough picture of where you were and where you needed to end up .. ie more effort required on initial orientation.

Engineering specialist in aircraft performance and weight control.
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  • Migraine
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Migraine replied the topic: IREX (May 2015) Ex10 Q15

Hi Bob,

Thanks for your reply and explanation.

I think I understood the location of NDB and where the aircraft was situated in relation to that station, on your question. However, I don't think I appreciated on where to intercept the 250° NDB track inbound.

Initially I overshot this track and then intercepted from above without realising that had I just simply extended the 250° NDB track inbound (on my first drawing), then I would have intercepted it anyway - although only at 40 degrees, and not the 45 degrees required by the question. (Please see the attached revised drawing illustrating this).

This is how I visualised the answer to your question, but is this a good way to pictorially understand this kind of question, or will I fall foul later on in the study guide as questions become more complex?

Thanks in advance for your continued support.
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