I’ve had this recently - the BA app suddenly announced (on the morning of the flight) that my flight to JFK was scheduled 15 earlier than the original booking; this was only spotted in the app, within about 3/4 hours of departure.

In those situations, does conformance at security in T5 (at T -35) also move forward, or does it stay by reference to the original departure time. On that occasion, I have to say that through a combination of factors I was actually cutting it VERY fine: I probably squeaked through “new” conformance by about 3/4 minutes, but if I’d been another 5 minutes later would I have been booted off, or OK on the basis it would still have been T-35 to the original timing?

It was, I have to say, really very stressful! I was already running late and mentally calculating I would JUST about make it, so to see myself lose 15 minutes for no apparent reason was very unwelcome!

Anyone know on conformance for these weird situation?

FYI - obviously in the end the flight departed “on time” for T5 i.e. pushback 15 minutes after schedule and take-off more like 50 minutes…