Another NDB IMC Question

[PompeyPaul]

This makes no sense to me:

18) You are heading 280, with the NDB on a relative bearing of 160. If the variation is 5 degrees west, what is your true bearing from the NDB?
A 080
B 075
C 255
D 260
You chose D, but the correct answer was C.

I completely guessed this. My working was:

1. Bearing to beacon = my bearing + NDB = 280 + 160 = 540 (180) degrees to the beacon
2. Variation west, compass best = 180M = 175T TO bearing
3. Bearing FROM the NDB = add 180 = 355T bearing

Which is COMPLETELY wrong! I've obviously done something extremely obviously wrong! I thought I had (1) absolutely correct but it's obvious I'm making a mistake there.

[Whopity]

280 + 160 = 440 not 540!

440-360 = 080 +180 = 260 M -5W = 255 True Answer C
There is of course another answer as 160 degrees Relative could be on the other side of the aircraft!

[Captain Gadget]

PompeyPaul

You are heading 280 with the NDB on a relative bearing of 160 - so the beacon is located 20deg to starboard of directly aft of you (100), i.e. 080.

The tail of the ADF needle (indicating your bearing FROM the beacon) is thus pointing 20 deg left of the nose, i.e. 260.

NDBs read Mag, so subtract the 5 deg variation to convert to True = 255.

I think that's it...

Gadget :ok:

[Dave Gittins]

My logic is a based upon a mental geometric construction.

I am heading 280. If the NDB had a relative bearing of 180 it would be behind me .. i.e. 100. But it's 160 therefore 20 degrees further north i.e 080.

Variation is west by 5 degrees so as I am going from a magnetic to a true bearing thats 5 off = 075.

If it's 075 to the beacon it must be 075 + 180 away from it = 255.

[PompeyPaul]

Thanks guys! I'm obviously in "be a dullard" mode today.

[Dave Gittins]

Blimey ... bit of a feeding frenzy at 14.03

[Captain Gadget]

Only because I woz still typing at 14:01...but Intercepted takes home the prize this time!

Still, PompeyPaul got his answer pretty quick...

Gadget :cool:

[Talkdownman]

Easy, if one thinks in terms of QDM, QDR, QTE and QUJ...

[UV]

You can make it as difficult as you like ..but...
280 (M)-5=275 (T) -20 (RB) =255 (T).

[Johnm]

Of course the correct answer is "Somewhere between 240 and 260 depending on the weather, terrain and whether it's day or night"

The other part is that I have an IR and I have no idea why I would ever be interested in the answer to this question and furthermore I can't remember the last time I looked at an ADF, though there is one in the aeroplane.

[Dave Gittins]

is the ADF the thing that gets Radio 4 ?

[lotusexige]

ADF+DI=QDM?

[Johnm]

Of course 160 means "somewhere behind my right shoulder" if you are heading 280 :-) That might be slightly helpful if you are following a parallel entry to a left hand NDB hold but otherwise radio 4 may be more useful.

[PompeyPaul]

If you are flying on GPS then you are an immediate danger to yourself and everybody else in the air :eek:

Transponder negative, nil radio, map, compass & stopwatch. That's the ONYL way to fly :ok: The Amish of the GA world!