GUWonder

This year too, I have often been tested in the Schengen zone on Day N — the day of my flying from Schengen airports to LHR — so as to overnight in London and then fly on Day N+1 to the US on the same-ticketed PNR that brought me into LHR from the Schengen zone. And it’s been the airlines at LHR that checked me for my compliance with the US testing requirement.

It’s rather frequently the case for me since 2021 that I test in say one Schengen country, originate a trip out of another Schengen country and have an overnight layover in London en route to the US. I haven’t had any problems with it, but I also don’t care to count on the Verifly-type stuff since things work fine for me at the airports on such US-bound itineraries anyway.

Testing two days before the LHR-US flight? While you shouldn’t be at the mercy of the airline reps or VeriFly type services on an itinerary that involves this kind of MAD-LHR+overnight LHR+LHR-US itinerary — since testing the day before MAD-LHR should work on a single ticketed PNR that has the LHR-US flight — sometimes it could depend upon whom you encounter at check-in (or with VeriFly or whatever) even as it can meet the US requirement.