wrote:
: Don't be dumb. The magnetic compass is legally required because it
: operates independently of any electrical supply, unlike any other
: navigational doodad you might have. And in some areas we fly here in
: Canada, the mag compass has saved a lot of lives when the rest of the
: goodies failed. An accurate compass and a pilot able to use it is
: absolutely necessary for finding the way home when other stuff quits,
: especially the GPS. There are no other navaids in much of this country.
: When the visiblility is low, you can miss your airport by a mile or two
: and never see it. A one-degree error on a 60-mile track is a mile off
: course, so we teach some of our navigation exercises in an airplane
: with nothing more than a compass. We have had alternator failures
: several times over the years, even with carrying out the 500-hour
: alternator inspections.
: On the other hand, the compass is mostly useless in the far
: North due to magnetic dip. Up there pilots sometimes keep the "sun's
: true bearing" tables aboard.

: Dan

Pretty telling a year or so ago flying along the Alaska Highway in the Yukon. A 60 mile long Victor airway between two VORs
might have as much as a 5 degree difference from end-to-end headings and "180-degreee reciprocal" headings. In the far Canadian
north, I know it's even worse.

-Cory

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* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
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