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-   -   ATPL GNAV theory question about relative bearing RB (https://www.pprune.org/professional-pilot-training-includes-ground-studies/663752-atpl-gnav-theory-question-about-relative-bearing-rb.html)

xplanefactor 21st January 2025 08:50

ATPL GNAV theory question about relative bearing RB
 
Hi to all, I need your help please on that question please:
A pilot spots a landmark on a relative bearing of 314°. The present compass heading is 255°, the variation is 26° W and the deviation is +2. What true bearing should be drawn from the chart to the
landmark?

001 ° 185° 005° 067° (apparently 005°) WHY?
I tried using this illustration joinded:


https://cimg0.ibsrv.net/gimg/pprune....ee8ae0e043.jpg
and a drawing but still cant find it. Many thanks!!

RichardH 21st January 2025 14:44

Talk about making life difficult along with not the best worded question plus an incorrect answer (as asked).

1. Resolve C D M V T = 255+2=257-26=231 True Heading (as answer wants True)

2. TH 231+RB 314 = 545-360=185 True bearing from aircraft/chart TO the landmark, so given the wording of the question 185 is the answer not 005.

However, in a more practical application you would usually plot from a fixed position (landmark) so you would take the reciprocal 185-180=005. Protractor on landmark, draw out 005(T) the aircraft is somewhere along that line then get another bearing from another station at least 60 degrees apart draw another line & you get an approximate fix.

A word of friendly advice, when others go to the effort of answering your questions for free (like I did for Polar Stereo) it would be appreciated you at least acknowledge our efforts afterwards.
RichardH

xplanefactor 26th January 2025 09:34


Originally Posted by RichardH (Post 11811592)
Talk about making life difficult along with not the best worded question plus an incorrect answer (as asked).

1. Resolve C D M V T = 255+2=257-26=231 True Heading (as answer wants True)

2. TH 231+RB 314 = 545-360=185 True bearing from aircraft/chart TO the landmark, so given the wording of the question 185 is the answer not 005.

However, in a more practical application you would usually plot from a fixed position (landmark) so you would take the reciprocal 185-180=005. Protractor on landmark, draw out 005(T) the aircraft is somewhere along that line then get another bearing from another station at least 60 degrees apart draw another line & you get an approximate fix.

A word of friendly advice, when others go to the effort of answering your questions for free (like I did for Polar Stereo) it would be appreciated you at least acknowledge our efforts afterwards.
RichardH

Dear Richard, many thanks for your answers, I am taking the time to read them and understand them fully, but your answers at very much appreciated!! Keep you posted, best!


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