I think this was discussed here a couple of months ago, but I didn't buy the argument that UA needed to move FAs because a LHR flight somewhere was canceled. I thought they could have moved the FAs and not had them work the flight?

I was surprised to see that more than half of the FAs on my IAD-LAX flight last week were London-based and British (though I'm told you don't have to be British to be based in London). It was UA947 on a 777. Has anyone else had that experience? I wonder what the regulations say about it. I'd guess a foreign FA needs a U.S. working visa to work on domestic flights.