I'm w/ prncss674 on this one. I nearly had a huge carry-on hit me in the face on the way to the London Do a week ago. Some (tiny) person brings on big carry-on that's packed full; she tries to lift into the overhead bin, staggers backward & falls forward. It falls to the spot where my head was & I jerk to the left to avoid getting hit. I was livid. I would have been hurt if I hadn't moved quickly. The FA didn't see it cuz she was in the galley, and some guy then got up to help the woman put it in.
If I had my way, no one would be bringing carry-ons (other than laptops, briefcases & small bags for essentials) on a plane, but that's a different thread/topic.
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Sharon