Compass Questions ?
Hello Bob,
I'm unable to provide the answer as to the technology employed by
computer-generated displays to display magnetic information, but I would expect
something like a Hall device might be employed. As you implied, it could as
easily be derived from GPS data corrected for magnetic variation at the
particular location.
Magnetic/compass headings are not true, but magnetic. Navigation Sectional
charts http://skyvector.com/ are depicted in True coordinates, and the
pilot/navigator must correct for magnetic variation in drafting his flight
plan. ATC expects all course/heading numbers to be magnetic.
You'll find more information he
http://www.faa.gov/regulations_policies/handbooks_manuals/, and he
http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2015.pdf.
Hope that helps.
Best regards,
Larry Dighera
On Mon, 13 Jul 2015 18:36:54 -0400, Bob wrote:
Hello,
Not a Pilot, but always interested in the engineering aspects.
This question came up, and I realize that I am not sure of a correct answer.
Regarding the compass heading that shows in the glass displays:
How is it derived ?
GPS ?
If not GPS, what ?
Is it then Magnetic or True ?
Does the Pilot have to correct for variation/declination changes during
a flight ?
Does aviation use True or Magnetic when discussing or flying ?
etc. ?
Thanks,
Bob
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