Originally Posted by
ANNIVONGIBON
I specifically fast tracked my TSA pre-check approval so that I would have it for this flight. I added the "Known Passenger" details a month ago but now I am getting an error.
I don't think that will help you get into the UK. You would need UK Registered Traveller, but that's not available for folks from the US.
Registered Traveller: faster entry through the UK border: Overview - GOV.UK