"Cub Driver" wrote in message
...
On Sun, 13 Jun 2004 15:58:11 -0500, "Stan Prevost"
wrote:

Dan, it is telling you that the airport is to your south. It knows its
current position, and it knows where the airport is, and it indicates the
bearing to the airport. The needle will not move if you rotate the unit
in
place, since a GPS receiver has no sensing of its orientation, only its
position. Go by the bearing it indicates, not whether the needle points
to
actual north or south.

But it's telling me to go away from the airport!

I know where the bloody airport is: it's beyond the south shore of
Great Bay. But the GPS is telling me to head north, toward town. In
that direction, 7B3 is 25,000 miles away!

Besides, I can't leave the continental U.S. with my recreational
certificate.

But that's only when I'm facing south. If I'm facing east, it's
telling me that south is east.

I realize that I could take the bearing off the GPS and use the
whiskey compass to navigate, but that seems a bit baroque.


You said the needle always points to the bottom of the compass rose, with
north always at the top. That means the needle is indicating that the
airport is to your south, as it should.

Draw the proper compass rose indication on a piece of paper, and turn around
and around with it. It will behave exactly as the display on your GPS.
Neither the paper nor the GPS has any idea where actual north is. Once you
start moving, it can figure it which way you are moving, and an HSI display
on the GPS will move to indicate your direction of travel at the top of the
compass rose (toward the top of your display), but it still doesn't know
where actual north is relative to the orientation of your display screen.
Stationary or moving, you can rotate the GPS around and the needle will
rotate with it.

Stan