OK, I want to post this to save someone some hurt. I was flying around my church this morning and decided to fly around a building next to it. Well guess what. I lost signal and realized that the height of my return home may of not been set right. So I quickly ran around to the other side of the building and cancelled the return home right before it smacked into the building. Lesson learned. Make sure that if you are flying in a city where there are lots of tall buildings, Don't let one in between you and the bird. LOS rule. I know, my fault. What may happen is a return to home and smack! I googled the tallest building in my city to see the height and from now on will set a return to home height taller than the tallest building. Could of been a painful lesson and I don't even have my extra batteries yet! I know, noob.