Two times now, my Phantom just dropped out of the sky when I throttled up. First time the battery may have been low. It was medium altitude and I was hovering and pushed the throttle up and instead it just dropped straight down like it ran out of juice. Second time, was also hovering and I pushed the throttle up and it just dropped straight down. It was still powered on and blades were spinning, just slow when I retrieved it. This time, the low battery wasn't flashing. So, what am I doing to drop my bird? I'm a bit concerned it will happen in a bad location.