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View Diary: How Airliners Work - Navigating the Oceans (75 comments)

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  •  What kind of navigational complications appear (4+ / 0-)
    Recommended by:
    Bronx59, sawgrass727, VTCC73, Simplify

    when flying in the high Arctic and polar regions?  As an example, let's say you're flying nonstop between Delhi and Chicago.  According to a Great Circle mapper I've just checked, the most direct point-to-point heading is 348.4 degrees, which is not a lot off due north.  The route takes you up across the Karakorams, Russia, past the SW tip of Novayla Zemlya, over Svalbard, then across northern Greenland, then Canada and on into Chicago.  So what happens to compass headings in those extremely high latitudes?  Any other navigational problem?  

    -7.13 / -6.97 "The people never give up their liberties but under some delusion." -- Edmund Burke

    by GulfExpat on Sun Jun 23, 2013 at 02:24:11 AM PDT

    •  Good question (0+ / 0-)

      Since the magnetic compass doesn't work up over the North Pole we use "True" headings instead of "Magnetic" headings up there.

      When I flew bombers and tankers, the navigators would do something called "Grid Navigation" when we got up around the Arctic Circle.

      I wish I could explain how grid navigation worked but that was an arcane secret known only to navigators.

      If the pilot's good, see, I mean if he's reeeally sharp, he can barrel that baby in so low... oh you oughta see it sometime. It's a sight. A big plane like a '52... varrrooom! Its jet exhaust... frying chickens in the barnyard!

      by Major Kong on Sun Jun 23, 2013 at 07:22:48 AM PDT

      [ Parent ]

    •  ... (0+ / 0-)

      Really late, I realize...

      But up in the far North, magnetic compass readings are problematic. In Alaska, they'll routinely get unaware pilots in huge amounts of trouble. The magnetic pole is in Hudson bay, so "North" on the compass is East. The dip (downward component) is also substantial, and the variability, large.

      Even down here in the continental U.S., maps are marked with the difference between magnetic North and True North ("isogonal lines"), and it varies up to about 10 degrees from True North. Magnetic anomalies are also marked -- there are places (e.g., low altitudes around Manitou Springs, CO) where compass readings shouldn't be trusted, due to magnetic rocks or other anomalies in the Earth's magnetic field.

      Finally, magnetic North wanders. Slowly, but enough that runways (which are named for their magnetic headings, divided by 10) are occasionally renamed.

      GPS makes all these troubles go away...

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