Hey all. This is beautifully done output from your GPS, accelerometer, and compass. Its not a game, flight sim, nor is it magical. Just the facts. If youve ever used GPS you already know that GPS wasnt designed for altitude and is notoriously bad about getting good altitude readings. You need signal from at least 4 satellites for starters. Their positions in the sky has huge bearing on results. A lot of times the angles are so shallow that it is tough to discern. I suspect it may work better if you are closer to the equator than I am. Bottom line, GPS altitude is roughly in the ball park. The rest of the GPS data is okay. Remember too that the phones GPS calculations arent as fast as a dedicated receiver. Doesnt update as fast. All that means is you have to wait a little longer for readings to settle in. The graphics are extremely well done. This app looks great! Its fun and works fine for what it is too. For the price you cant go wrong. The full paid for version is worth it too. (the HUD is cool) Enjoy!