"Everett M. Greene" wrote in message
...
"Icebound" writes:

"Northern Domestic Airspace" uses TRUE north headings only and no
magnetic nav due to unreliability.

When operating in this airspace the rules call for the aircraft to be
equipped with "a means of establishing direction that is not dependent
on a magnetic source"

What does one use for such a means?

GPS, Inertial-Gyro systems, and celestial nav.

You take a course such as this:

http://people.aero.und.edu/~deremer/courses.html

and pay particular attention to Level 3, number 2 :-) :

a.. Navigation without magnetic compass: gyro errors, finding & using the
sun's true bearing, and finding true north without celestial reference