On Apr 5, 4:35 pm, wrote:
In rec.aviation.piloting DR wrote:

Mxsmanic wrote:

There
are plenty of spots on charts where the compass will be 6-8 degrees off even
from the already irrgular declination over larger areas.

LOL! My BS meter just went off scale! Declination? Lines of magnetic
_variation_ are plotted on VP charts and better than 0.5 degree accuracy
(except at local anomalies which are only noted in nautical charts as
far as I've seen so far). Declination in navigation is actually
something else but I'll let you googgle for it.

I can't think of any local anomaly that is both strong enough and large
enough to be anything other than a transitory "burble" at most to the
compass of an airplane in flight.


Yes, I agree, that is true of most but some are very big, the biggest
is in Kursk, Russia. If your autopilot is flying a magnetic heading
how fast would it respond if it flew over a common 6 degree anomaly?


Cheers MC