On Wednesday, July 15, 2015 at 7:40:25 PM UTC-7, V1 wrote:
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

Ah no. Hell no. No better than hanging a rock on a string in the cockpit would help you.

Artificial Horizons rely on gyroscopes not accelerometers. These inclinometer apps just use accelerometers to compare the phone inclination to the local gravitational field direction. Moderns smart phones do have gyroscope sensors as well as accelerometers and can drive "artificial horizon" toy apps.. If survivign flight in IMC is of any real interest/concern you are not going to be dicking around with a smart phone.