Are you sure about that? From what I understand, the section lines are
aligned to magnetic north, not true north. So when you follow a
section line going west, your compass should show 270.

Guenther
----------------------------------------------------
Guenther Eichhorn | gei@cfa.harvard.edu
Smithsonian Astrophysical Observatory, Cambridge, MA
CPL,ASMELS,Glider,LBH,IA,CFI | Pitts S-2A: N1GE
DC-3 type rating | Flying is the Pitts
See: http://acro.harvard.edu/ACRO
and: http://acro.harvard.edu/SOARING

In article <20010110110318.19141.00000067@ng-fw1.aol.com>,
dsowder@aol.com (DSowder) writes:
|> Swinging a compass on the ground can be difficult for a couple of reasons. For
|> one, most compass roses are about 30 years old, and mag. variation has changed
|> since then. Plus, you're supposed to do it with the tail up and the engine
|> running--I suppose that cruise RPM would be most appropriate. There's re-steel
|> in that concrete apron, too, not to mention the cell phone tower just built
|> nearby. This job could take a week.
|>
|> Here's how I do it:
|> Magnetic variation around these parts is 19 degrees East. So, I go out on a
|> reasonably calm and smooth day and fly straight down a section line headed
|> West. Don't compensate for wind drift (i.e. keep aircraft heading, not course,
|> parallel with section line). Compass should read 251. If it doesn't, I correct
|> it with my non-magnetic screwdriver.
|>
|> Then I make a 180 degree turn, and fly East down the section line. Compass
|> should read 071. If it doesn't, I adjust it so as to take out half of the
|> error.
|>
|> I then turn North and repeat this process for North and South, then do the
|> whole thing one more time since N-S corrections affect the E-W corrections.
|> This procedure gets the compass about as close as you can get it.
|>
|> I don't know about doing this in Canada. Things are different there. Not to
|> mention the fact that, being so close to the magnetic north pole, mag.
|> variation could change by the second when flying east or west! All bets are off
|> for Australia, as we all know that a compass behaves erratically when upside
|> down, and bathtubs swirl the wrong way...
|>
|> Doug Sowder

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