Austin Bay writes about navigating when GPS isn't available. He reports that a Kazakh helicopter gunship recently found its way across a snowbound landscape the old-fashioned way.
... there was a recent incident in Central Asia (that was caught on a cell phone video and widely distributed) showing a Kazakh Mi-8 helicopter landing on a highway and asking people in the next vehicle to show up where they were on a map. A truck driver pointed to where the city was they were looking for and the helicopter went on its way. The Mi-8 crew were on a training exercise to see if they could navigate without GPS and back in the old days that sometimes involved landing and asking for directions.
There's more at the link.
Here's the video, shot by a Kazakh trucker.
I imagine a snow-covered landscape, with all landmarks or identifying features hidden beneath the snow, must be almost as difficult as the open sea, out of sight of land, as far as navigation is concerned. Without electronic aids, one's reduced to a great deal of guesswork.
(On the lighter side, I'd hate to be a traffic cop trying to give the pilot of a fully armed, missile-equipped helicopter gunship a ticket for obstructing traffic!)