In message , at 11:36:29 on Sun, 11
Sep 2011, Clive D. W. Feather remarked:
BA certainly used to have "set-down only" stops. So the flight from
London to Pittsburgh (IIRC) had a set-down stop at Washington Dulles.
Those passengers to Pittsburgh just stayed on the plane while those to
Washington got off, after which the plane continued on its journey.

20 years ago I recall catching a plane that flew Gatwick-Houston-Dallas,
probably a route BA inherited from BCal. We didn't have to get off at
Houston, but I suspect no-one got on either (trade barriers) so we could
be treated as 100% international arrivals in Dallas.
--
Roland Perry