HI all, I was asked to fly over some skateboarders at a skate park in the Milwaukee area today. I learned something. I don't know what it's called, but that metal lip at the edges that they slide along in the pits and ridges and rails and stuff... well, if you start up your 'copter in that vicinity, you're going to have all sorts of compass issues. Furthermore, even with a hood, I could hardly see my iPad, so calibrating (which didn't work anyway), was nearly impossible. Oh, then I walked away about 20 feet, and it was fine. GPS mode fired right up and flying above all that metal wasn't a problem. But starting it all up on the concrete a few feet from those ridges... not so good. Once we got that worked out, we got some nice stuff, I think. Just something to keep in mind.