Here is some insight to Polar Navigation and it's application...
Thanks to Bob Nyden  who proves that you can get there from here..
He was a navigator in VXE-6 along with Bob O'Keefe from '71 thru '74. He forwarded part of an email to me in which you asked about grid navigation:

>Hi Bob O'Keefe, ( same as 644 navigator ? )
>Thanks for the neat input to the connie page via Noel.
>Been looking for someone who understands polar grid navigation
>to make the connection from celestial to grid.
>It makes sense but I just don't connect the dots as yet.
>Am somewhat OK with celestial from going to sea.
>Would make a good piece on if ya like..
>73s from Dave Riley, VX6, 64-67, 644 Radio
Here is a part of a long story I once wrote about flying from Christchurch to the Ice. We've reached cruising altitude and turned on course abeam 4YA (Oamaru East):

Now it was time to switch over to grid navigation. Over most of the world the familiar magnetic compass, when combined with suitable corrections for local variations, is perfectly adequate. But as one approaches the poles, the magnetic compass becomes less and less reliable and the corrections larger and more frequent. So as a convenience, charts of the polar regions have been overlaid with an artificial square grid which ignores magnetic influence and eliminates another bother of standard charts, the convergence of lines of longitude at the poles. This grid is arranged so that north and south lie along the great circle which creates the Greenwich or 0 meridian, and the 180 meridian which roughly creates the International Date Line through the Pacific Ocean. On the C-130, our gyro-driven compasses, which were normally tied to the magnetic system, were reset to align with the grid system whenever we headed south to Antarctica. As a matter of convenience and safety the conversion usually took place just after passing the last reporting point associated with New Zealand, namely Oamaru East. Thus if anything went wrong with the compasses during the switch, we could easily return to base using the backup magnetic compass. About the only problem with grid nav was that it relied on a very stable gyro compass, one that precessed (gained error) very little. Normally ours could be depended upon to vary only one degree an hour, but only reference to the outside world, usually by taking a sight on a celestial body, could verify that the gyro was holding the proper grid heading. I was hoping that we would be able to take a sight within a few hours, because for every degree of compass error that I couldn't detect, we would drift four or five miles off course every hour.
An ironic result of the arbitrary alignment of the grid system was that our southerly true course became a northerly grid course. In fact the course to McMurdo now was 354 grid, almost dead on "north." It always amused me to watch visitors to the flight deck as they sorted through the imposing array of instruments until they found the compass, only to discover that somehow to go south you had to go north!

Grid nav was really great--much easier than using the magnetic compass because you didn't have to worry about magnetic variation corrections, and the grid printed in nice regular 30-nautical-mile increments (half a degree of latitude). I think the Air Force used grid nav all over the world. Certainly the nav charts all have the grid printed on them. Celestial worked much the same as in the "real" world because the grid is aligned to the same true north. Estimated positions for calculations were still the standard latitude and longitude. The trick was in calculating the direction you had to point the sextant to find the celestial body, that is the azimuth angle (Zn). What you did was add your East Longitude (or subtract West Long.) to the normally found azimuth angle and use that and your grid heading to find the bearing to the body. This is akin to the rule for converting magnetic heading to true heading: "magnetic-to-true-add-East (variation)," but here it's "true-to-grid-add-East (longitude)." (A similar calculation is done to find the local hour angle (LHA) when computing the sextant altitude (Hc), whether you're using grid or not.) It was easy (and important) to check the gyros for precession by calculating the bearing where the Sun should be relative to the airplane and comparing that to the actual azimuth angle. At the Pole, it was necessary to use the skiway alignment as a reference to check the gyro because there was no telling what line of geographical longitude you were on.

Hope this helps, Dave. If you want more info, I'd be happy to try.
Bob Nyden
OAE '71-"74

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