> I don't see why a manual for an airplane mechanic is better smack-dab against his eyeball but a map in one's line of sight is not better for a person navigating.

If I'm performing a series of complicated manual tasks, I'm going to need both hands free. It's a pretty safe bet on something the size of an airplane that I'm going to be moving around a fair amount, too.

My phone, giving me turn-by-turn directions, will always be just a foot or so away from me, and clearly visible from the driver's seat. I don't benefit from having it "smack-dab against [my] eyeball."