Nor can I, unless there is a special channel for OSS passengers, or people are taken directly to their departing connection aircraft. But on both sides of the Atlantic the point of the scheme is to remove the need to security check a significant chunk of passengers, since they have already been screened to a high standard. The roll out of CT scanners globally clearly helps here. So for TSA they benefit if CBP can allow passengers to bypass an unnecessary check, without being in contact with non OSS passengers - and they see this as a shared endeavour. I think we will have to wait a few weeks to see how LHR handles this (which is the departing aircraft model where possible) to see how the TSA end can work.