Remember to pull down the throttle to zero if you see your quadcopter going out of control and about to crash or collide with something. Always stay away from spinning propellers or do not handle a quadcopter when the propellers are rotating.
This happens when you’re trying to teach someone else to fly and then try to pick it up. When the transmitter is in someone else’s hands and it is on, the propellers can start spinning anytime, so be very careful!