Hello,

AFAIK, there are some kinds of turbulence: "light" (the water in the glass shakes), "moderate" (the glass can fall from the table), and "severe" (the plane can't keep it's flight level and can be for a short time out of control).

Since I've experienced once "severe turbulence" (it was on a thundersturm during the descend to EZE, when we dropped 2000ft according to the pilot), I was for a long time quite scared when the plane began to shake.

But: It is very very unlikely that a plane falls from the sky because of that. Light or moderate turbulence happen on almost every flight. And, I know it: Every airliner bears more than the human stomach!

Patrick