0
$\begingroup$

In my PPL trial test, I have the following question regarding an NDB:

Consult Figure 3, Illustration 6. On a magnetic heading of 160°, the magnetic bearing to the station is:

  1. 045°
  2. 205°
  3. 165°
  4. 270°

(See the attached figure, illustration 6)

Looking at the figure, I see a needle pointing to 045°. Therefore, I conclude that when my heading is magnetic north (as the heading of the aircraft is shown in the figure), the magnetic bearing to the station would be 045°. Consequently, I deduce that if I am heading 160° magnetic, then the bearing to the station would be 115° to my left, i.e. 360° - (160° - 45°) = 245°.

The reason I think this is because, as I am turning eastwards the magnetic bearing to the station will decrease until I reach a heading of 45° magnetic at which point the magnetic bearing to the station would be 0°. As I turn eastwards more, the magnetic bearing to the station would flip around at 360° and keep decreasing. I need to make a starboard turn 160° - 45° = 115° more to reach the desired heading 160°, so by that time the bearing would decrease from 360° by 115° to reach 360° - 115° = 245°.

Nevertheless, the test claims that the correct answer is 205° (which I'm guessing is, for some reason, calculated as 160° + 45°). Could you kindly explain what is wrong in my thought process or interpreting the ADF instrument?

$\endgroup$
  • 1
    $\begingroup$ Based on the correct answer below, it is now clear to me that the instrument depicted is an ADF, not a VOR, as it depicts the relative beating TO the station, but with a Fixed Compass Card (see navfltsm.addr.com/ndb-nav-adf-1.htm). The magnetic bearing to/from the station does not change with heading. $\endgroup$ – dionyziz Oct 2 '18 at 7:27
  • $\begingroup$ I edited your question to fix some terminology: the pictures are of an ADF, not a VOR receiver. A VOR would have a to/from flag. $\endgroup$ – Pondlife Dec 20 '18 at 3:13
3
$\begingroup$

I think the figure is just intended to illustrate the bearing to the NDB relative to the aircraft, and not the magnetic heading of the airplane. So when they give you your magnetic heading of 160, you're still using the bearing of 045 relative to your aircraft, which gives 205 magnetic.

$\endgroup$
1
$\begingroup$

MB=RB+MH for fixed card ADF. as shown here Airplane now heading 160 from north " nose of airplane " relative heading now is 45 from heading of airplane " from nose " it means station is located 45 degrees from your heading which is 160 degrees north so the magnetic bearing to the station equals 160+45=205 hope it helps

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.