[jschwartzi]

Compass, Altimeter, topographic maps, notes about the route that I've made. Even a watch can aid navigation if you can calculate your speed and see any terrain features.

If anything doesn't jive with what I expect or what I'm seeing I try to understand why.

[lisper]

Sure, when you're VFR it's pretty easy to notice that your GPS is flying you into a mountain. When you're IFR, not so much.

[anovikov]

Maybe there is a market for civilian version of DSMAC?