You mean Real Flight? Great Planes makes it. It's a good sim, but it was designed for the graphics. A friend and I have gotten some of the planes to fly EXACTLY like the real ones we've flown at the field(he and I are instructors so we fly other peoples planes more than our own). Don't get me wrong, Real Flight is pretty good, but it isnt very accurate on some planes like the funflys or aerobatic planes. Plus you cant see the ground in it unless you are flying low. I've had it over a year and I still loose orientation to the ground. I flew a copy of Ripmax RC Simulator once, and it was the most accurate I've seen. You knew exactly where you were all the time, and the planes flew perfectly. Plus when you hit something, your plane actually breaks up. If you hit the fence, you can snap the wing off, and then see the plane fall down and break up more when it hits the ground. The sound is more realistic aswell. The engine sounds exactly like the ones in real life. There is a more limited selection of airplanes and flying fields, but it covers almost every kind. You can still download airplanes like Real Flight, and customize them.