One Handed Helicopter is an Advanced Hula Hoop Trick. This trick is sort of a continues Palm Spin.

Start with a regular Helicopter and spin in the same direction of the hoop.
Then, with your dominant hand spin the hoop in an infinite motion until the end of the move. While performing the One Handed Helicopter your dominant hand, holding the hoop, should be fully extended and facing up.

hoop.tip:
★ Practice the hand spinning motion pointing downwards first. When you feel comfortable try raising your hand slightly and repeat until your hand is fully extended.
★ Check out Lisa Lottie’s tutorial for this move in order to better understand it.