Guys, Took the Phantom out for a spin today @ lunch. I work near an office park. There are several large buildings, and it is a very overcast like day. We attempted to launch @ one location, but could only get 4 satellites and no GPS lock. We shuffled over about 500 feet to another spot. Got GPS lock right away. I take off, bring the Phantom up to 300 feet, and see some yellow NAZA lights a few times, but pretty quickly the Phantom went right into fail safe mode. It landed properly (I caught it), but it was a scary moment for me. I haven't yet practiced initiating intentional fail safe and then taking over via manual control. I was hesitant to do that bc I never have in a controlled environment, but will do so now. Anyway, here is the question: What happened today? I think I need to understand more about what interferes with the transmitter connection to the Phantom. Several tall (30 story) buildings around may mean there are cell towers on them. There was also a power-line and transformer about 100 feet away. What causes the bird to lose connection to the transmitter? Thanks!