When Quadcopters Attack

http://www.theverge.com/2014/11/13/7205741/i-almost-killed-someone-with-a-drone

"The next day I took the Phantom out in the middle of the afternoon. I was about 50 feet off the ground, doing some speed runs to the tree line and back. At some point the GPS signal must have dropped again, because the light switched from green to red. I brought the unit to a halt, hovering it in front of me.

A strong gust of wind came through and suddenly the Phantom was drifting quickly towards my in-laws' house. Without GPS, the unit wasn’t correcting for this at all, and I didn’t want to break any windows. So I tried to correct hard back against the wind, but the breeze had also rotated the unit, and my orientation was off. Instead of fighting the wind, I actually doubled down, accelerating the unit over the house and out towards the road in front.

At this point I panicked. I couldn’t see the drone and wasn’t sure how to recover. So I decided the best thing to do was go to ground. I killed the rotors and listened with horror to the sound of my Phantom impacting into concrete. I think all this happened in less than two or three seconds.
I came running around to the front of the house and found a woman on a bike, stopped by the side of the road. On the back was a small child in a bike seat. Both were wearing helmets. My Phantom was strewn across the road in several pieces.
It was hard to tell how far in front of the drone they had been when it came down, but they were clearly shocked. A few seconds earlier, a few feet to the other side, and it could easily have come down on them instead. There is no way to say exactly what would have happened, but a heavy object falling out of the sky, striking someone in the head, at which point they crash their bike, certainly could have ended in serious injury or worse."

This is why I get very nervous when I see a quadcopter flying over a crowd.  Things go wrong. Blades twirl.  It's a bad idea.  Stick to the open fields.