Roger (K8RI) wrote:

On Tue, 12 Sep 2006 12:48:35 +0200, Mxsmanic
wrote:


Thomas Borchert writes:


Yes. So?

So the compass cannot always be trusted.


The *only* time a compass can almost be trusted is in straight, level,
and un-accelerated flight. We make turns based on the TC and a watch
not the compass. OTOH you don't have to worry about it precessing like
the DG. I can roll into a CW turn and watch the compass show a CCW
turn. I can accelerate on one direction and it'll show a left turn.
Accelerate in a different direction and have it show a right turn. Of
course decelerating will show turns opposite of accelerating.

It is still trustworthey as it does the same thing in the same
conditions every time. That is most people's definition of something
you can trust. The acceleration and turn errors are known and
predictable, what is there not to trust? The only thing that makes a
compass not trustworthey is an unknown magnetic field that may have been
brought into the airplane.

If you didn't learn to understand and compensate for the characteristics
of the standard aviation compass during your flight training, then it is
your instruction that was not trustworthey! :-)

Matt