There are lots of bubble/level apps available for both Android and iPhone. I played with one on the ground (it combines a level and compass) including doing simulated steady state turns; it seems accurate and repeatable. I wondered if it could function as an artificial horizon in a pinch, like descent through clouds? I haven't tried it in flight (where it may react differently than on the ground), since it would be a distraction to do significant testing in anything other than a two-place.

Has anyone actually tried to use one in flight, without reference to outside horizon?

- Frank