I think I learned something yesterday. I was in an open space park flying and went through my batteries except one. So i made the battery change and started to walk the FC40 to the parking lot. I had walked for about 15 minutes to spot where i flew. as i was walking the FC40, all of a sudden it was like it hit a barrier. i could go side to side, backwards, and forward just to the "barrier". so i shut it down and thought i would walk a ways and then fly it to my truck. i got in sight of the truck, started it up, and walked it toward my truck. it would travel in any direction at this time. then all of a sudden the barrier showed up again. it wasn't until i was driving home that i realized the barrier was my limit from the home point. i was under the impression the flight limit was from the tx. it was puzzling. when i was setting up the FC40, i set the limit at 200 meters. now i know.