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by kylehotchkiss 671 days ago
Year round aviation access to Antartica. Well Done! Every step towards McMurdo becoming a normal city despite its location seems like such an incredible accomplishment.

Can this work at pole station too? I realize there's a lot of other considerations landing there in the winter (fuel freeze temp?) but the less isolated it becomes, the more science we can get.

1 comments

I'm guessing there are a whole bunch of assumptions and simplifications in standard aviation practice around lat/long, GPS, and magnetic compasses - which all fail at the pole(s).

I bet it's "quite exciting" to be a pilot trying to fly at the pole doing anything apart from flying straight and level right past.

Your longitude readout becomes useless as the lines of longitude converge. Your GPS altitude becomes wildly inaccurate because the orbital inclinations of the constellation means they never get above 45 degrees or so from the horizon. Your compass is pretty much trying to point straight down (and at the magnetic pole which is some way apart from the rotational axis of the earth pole).

And it's cold, likely very bad weather, the landscape make orienting yourself and even seeing upcoming mountains challenging, and you are a long long way from a safe landing spot and even further from any realistic help.

Flying over north pole became quite popular due to great circle routes going that way. use of GPS in civilian aviation actually came from compass getting confused during polar flight resulting in heading reversal. GPS satellites also supported polar operations from the start as the critical user needed flights over north pole. (this is one of those cases where typical map projections confuse people).

That said, magnetic compass deviations are common all over the world due to things like iron ore veins, so maps have corrections available.

GPS isn't used for altitude in aircraft in practice, it's too inprecise - barometric altimeter plus radar altimeter are the precise instruments for that.

> use of GPS in civilian aviation actually came from compass getting confused during polar flight resulting in heading reversal

Do you have a source for that? I was under the impression that INS-based navigation was much more precise than for that to have been an issue by the time GPS became available to civil aviation.

While GPS was apparently always planned to be provided for civilian navigation, Korean Air Flight 007 being shot down due to error in navigating over north pole led to explicit mention by White House:

https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007#Af....

KAL007 was an usage error of the INS mode of the aircraft's autopilot, though, which was itself working as designed (although that design was a bit of a footgun in retrospect).

The exact same error could have happened for a Pacific crossing near the equator. Magnetic aberration being larger near the poles had nothing to do with it.

I think a lot of aviation navigation is by named waypoints on charts. I am definitely not an expert, but I believe some of these would be visually identifiable in good weather, or even identified by radar transponders. Compas deviations would certainly be an issue, but I believe are important to account for even in much more populated areas. Aviation does use gps now, but many of the previous systems still exist and are quite clever. The ILS system this is based off of is such a system.