reply to post by jumpingbeanz
I think you're asking this to reference another of your threads about "pole shift"??
If so...do you not understand how MAJOR such an event would be?
For aviation and maritime navigation, just to name two aspects. Any huge change in magnetic pole direction would be IMMEDIATELY noticed!
Over the years, the magnetic pole can vary a little bit....even if it is measured in terms of miles or kilometers, it amounts to only a fraction of
degree, when measured relative to 'TRUE' North, or South. ('TRUE' refers to the axis of Earth's rotation).
Here is a small example, of real-world change. Taking just ONE airport in the USA, to illustrate: National Airport (KDCA) outside Wahington, DC.
The primary runway there (currently) is aligned north/south. Runway numbers aren't random, they are assigned according to the magnetic direction,
rounded to the closest ten degrees.
That is hard to understand, so let me explain --- Say a runway heading, when measured, is 360 degrees (north). Then, that runway is numbered "36"
(pronounced 'three-six', NOT 'thirty-six'). of ocurse, the reciprical is '18' ('one-eight'). See, the last zero is dropped, and the number
is rounded up or down according to which it is closest to.
I mention this because, about ten years ago, at KDCA the runway (main, longest) was "18/36". It is, today, "01/19". Why?
Well, more and more accurate measurements are taken, periodically. And, to maintain standards, the runway designations may change to reflect the more
accurate magnetic direction. BUT, how much change?
Well....look at the difference between 360-degrees (or, 000-degrees) and 010-degrees.
IF the runway is actually aligned at 004.9 degrees....then it is rounded down to "360", and called "runway 36". IF it is at 005.1 or more,
clockwise towards 010, THEN it will be "Runway 01".
It is a matter of fractions of degrees, sometimes, that will result in a numbering change. AND, that is about all that the minor magnetic pole
'movement' does...fractions of a degree of change, hardly significant at all. Even IF it moves many miles, in the Arctic or Antarctic. The pnaet
is very large, and the difference is very hardly noticeable (except to those who are persnickety about such details).
Here, I have linked the actual and current graphic for the KDCA airport --- it is the Airport Diagram and is commonly understood and interpreted by
You can see, fromthe diagram, the actual and precise runway heading (magnetic) for RW 01 (the chart fails in proper nomenclature, IMO, so they just
use a single numeral "1") is 006.2 degrees. That "rounds up" to '010'.
Conversely, the other direction is 186.2 degrees, rounds up to '190'.
I don't have to older charts, of course....but there are aerial photographs of the airport, on display, that show the SAME runway in its previous
number iteration....'18/36'. I remember flying there, years ago, when it was that way, and remember when it changed (just not exactly the
year...just, I knew and understood why
things change, in the way I have just described).