Pretty well all passengers have seen the occasional bit of chop. Nothing of any real consequence, and you could probably walk down the aisle if you had to. But, they then think that that, or perhaps something slightly worse, is actually turbulence. This forum has lots of regular flyers, but I'd reckon the chances are, that across the entire forum, only a tiny percentage have ever seen real turbulence.
The upshot of this though, is that people think that they can hold themselves in the seat (or in position on the floor). Good luck with that.
Unfortunately I think I’m in the category that has seen it.
However it wasn’t CAT, it was convective.
Details are in a TR somewhere but was MEL-BNE sector on a 738 with a classic early evening Brisbane storm.
Crew specifically said they were ending service early and the seat belt sign would be on earlier than usual.
I was in about row 24 having taken the flow-forward option.
As the crew were doing a final collection of rubbish etc the captain announced “Passengers and crew seats
immediately.”
There was no mistaking the emphasis on “immediately”.
The CSM made it to the crew seat at the front.
One crew member sat in a vacant seat in about row 12.
But with no other seats in the cabin, the other two headed for the rear galley.
One made it, the other didn’t.
She was flung into the air beside me but did not hit the ceiling.
Somehow she’d kept a grip on one armrest.
Even so when the G’s disappeared she hit the floor hard.
She had no serious injuries, but with moderate chop continuing she remained on the floor for about one minute.
I’m not sure if she was composing herself or decided sitting in the aisle holding armrests tightly was a better option.
Some loose items were thrown about, but nothing like the SQ incident, and all the carts had already been stowed.
Not fun.