Calibration is part of the newest update, and to be honest, I believe it is not worth it. I believe this for more than one reason. Firstly, I don't remember the game having any problems without it. Secondly, it doesn't work very well (at least not in my experience using it). It keeps on calibrating it so that if I hold my phone level, not at an angle, it makes the plane go left. Pair that with the sensativity, and I can barely fly. Its ruining the game for me. So please either fix it, or get rid of it.