[Sacajaweau]

this has been mapped for hundreds of years...why is this posted?

[scrabblehack]

Maps often use “grid north.”

For instance, Universal Transverse Mercator — if you’re near longitude 6x + 3, with x an integer, true north and grid north will coincide. Otherwise they will differ slightly.

Albers is even worse — you need to be on 96 W for grid north to equal true north.

[ChronicMA]

so what is more accurate?

using a magnetic compass or tracking which side of a tree the moss grows on

[grobdriver]

This is not news to any pilot anywhere - although GPS has changed the navigation game.

[dagunk]

Yeah. Had to pull down a long wire HF antenna and reset it up by Yakima. Found a magnetic variation map, lines make a hard right turn up there and then turn back roughly north. I was right in the middle of it.

Cussed a little, got back to work.