I don't care where you are using a compass, using it on the ground, not moving from that location, and not allowing other large masses of metal to move near you, one can 'CALIBRATE' it for that location.

I don't care if is deviation or variation that is causing the needle to move, you are compensating for both...

I used celestial navigation, in an airplane in the early days, but if one has an overcast your octant was excess baggage at that time....

If I had a chart, knew the territory, and could line up two fixed points of land I could fly directly between those points, and thereby get the compass calibrated for that heading...

The deviation could change of course, if I made a turn, but I had at least one accurate heading...and few places in the world exist that changes variation that rapidly...

And we would "swing the compass" on the ground, and use compensating magnets to reduce the deviation...

And when your "landing field" the carrier is moving those methods, along with a plotting board got me home...

Standing on the ground orienting and antenna, sort of simplifies the problem!!

73, Dave, WB6LLO dguimon1@san.rr.com

Disagree: I learn....

Pulling for P3E...