Need help with an NDB question

[giladal]

Getting ready for a written test in a couple of days...

An NDB bears 279 degrees relative from an aircraft heading 209 degrees (C).
With deviation of -7 degrees and variation of 18E. What is the bearing of the aircraft from the NDB.

I tried adding the heading plus the RB and subtracting 360 =128 degrees
then subtracted the deviation which brings it to 121. But the answer is wrong.
I dont know why to use the variation as i dont need to change it to true unless I am wrong...

Any takers?

Thanks,

[Dekka]

see if this helps...
luizmonteiro - Online Simulators - ADF Simulator (http://www.luizmonteiro.com/Learning_ADF_Sim.aspx)

[giladal]

Hi,

Try using the simulator, but i cant get the right answer which is 301M.

[Nashers]

209-7= 202M being the direction your traveling.


An NDB bears 279 degrees relative from an aircraft heading




therefore 81 degrees to the LEFT of the aircraft heading.

202-81= 121 TO the NDB


What is the bearing of the aircraft from the NDB


therefore 301 FROM the NDB

RTFQ!!!!

[helimutt]

Cadburys dairy Milk Is Very Tasty

C D M V T

Compass-Deviation-Magnetic-Variation-True :ok:

[StraightLevel]

I recon it is 315degM, or 333degT.

So what's the correct answer giladal?

[bfisk]

An NDB bears 279 degrees relative from an aircraft heading 209 degrees (C).
With deviation of -7 degrees and variation of 18E. What is the bearing of the aircraft from the NDB.

Compass heading 209 - deviation 7 = magnetic heading 202.
Relative bearing 279 + 202 = 481. Subtract 360 to get QDM 121.
Add 180 to get QDR = 301.
For plotting on a chart correct for variation at the aircraft (not at the NDB), ie line to plot = 301M+18E = 319T.

So 301M or 319T depending on what you want to use it for.

[Nashers]

the answer is 301.

all the info you need is in the question as i have explained in my last post above..

[2close]

The first point to note is that the question doesn't specify a True or Magnetic Bearing.

Nor does it specify whether the value of the Variation is applicable at the aircraft or at the NDB. Most questions of this nature tend to give two different values for Variation, one at the aircraft and one at the NDB, to test your knowledge of which one to apply. NDBs emit omni-directional signals, the bearing of which is measured at the aircraft on the ADF and therefore, if applicable, Variation is applied at the aircraft.

If the question was looking for a True Bearing from the NDB to the aircraft then the answer would be 319°T.

C = 209°C
D = -7°
M = 202°M
V = 18°E
T = 220°T

(T)HDG + RB = QUJ
220°T + 279° = 499° (-360°) = 139°T
The Reciprocal (QTE) from the NDB to the aircraft = 139°T + 180° = 319°T

If, on the other hand, it was looking for a Magnetic Bearing from the NDB to the aircraft then the answer would be 301°M.

C = 209°C
D = -7°
M = 202°M

(M)HDG + RB = QDM
202°M + 279° = 481° (-360°) = 121°M
The Reciprocal (QDR) from the NDB to the aircraft = 121°M + 180° = 301°M

We have two potentially correct answers:

301°M
319°T

Being a multiple choice exam, which one fits the given answer options?

As you've already given the 'correct' answer as 301°M it seems that Magnetic Variation is being ignored.

[helimutt]

or you could just wait a couple of years until all of the NDB's have been decommisioned. GPS Rules!:ok:

[Pugilistic Animus]

Usually on IFR flight all directions are magnetic and on VFR all are true:)

[giladal]

Hi Guys,
Been so busy studying for these 5 written exams. Have a few more days to go.
Thank you so much for the replies.

I was able to solve it per the "Read the question" remark. :) I think the answer was 301M.

I have another question but ill post it as a new thread.

Thanks again,
giladal