I'd love to know how a CC member can decide, with any certainty, whether it's safe to go to the loo, when the belt sign is on, without asking the aircraft commander.
Well, that's because pilots talk to other pilots on the radio who report the severity of turbulence up ahead to each other. They use highly technical words like 'light', 'moderate' and 'severe'. CC undergo gruelling training so that when pilots communicate this information, (when we call them, when they call us, during the pre-flight briefing) we can understand. They might even dumb it down for us and say something like, 'we can expect some pretty heavy turbulance over the Alps, so I'll keep the belts on and no trolleys till I call.' Therefore, we don't decide with certainty, but we can help as best we can given the information at hand.
Does that help F3G??