^ People have trouble thinking about motions in space, since they're used to having a nice stretch of terra firma as their absolute reference. They know that when they roll their car, the bystanders, sidewalks, and trees aren't really aren't spinning around in crazy circular paths, their head is. People can think of their airplane flight as the Earth falling away, tipping up at an angle, moving way down, spinning slowly around as they line up on the runway, then coming back up to kiss the plane's wheels as they land, but they know that's not a good way to describe things. But in an aircraft centered coordinate system, that's actually a pretty good way to think about it, where the pilot can work to keep the planet level, not the plane, and it's equally valid. I wonder if we should tell him about shooting a monkey with a blowgun, and how changing a reference frame can turn mathematically difficult problems into trivial ones?