The Independent had this to say...
Dozens injured as US flight hits turbulence - Europe, World - The Independent
The turbulence was "just a huge up and down", said passenger Kaoma Bechaz, a 19-year-old Australian in the US to visit her boyfriend.
She told the Denver Post that the head of the woman sitting next to her hit the side of the cabin, leaving a crack above the window, and a girl across the aisle flew into the air and hit the ceiling.
Ms Bechaz said she was not thrown around because her seat belt was tight
Go figure!