Originally Posted by
scottishpoet
1/ because the departure transit trains really only go one way, from B to C, they do not want people going into B via B security, then finding out their flight departs from A and getting on the transit train
2/ Volume... I doubt the small transit security at B could handle all the transits from B and C wanting to enter the departure area.
3/ biometrics & passport control ... while not relevant for your flight, B does not have the ability to take the photo for anyone getting on a UK domestic flight nor does it have Uk border capability. Since, until recently, all domestics left from A, again it made sense to limit the entry via B to those with flghts departing from there
these are just a few of my ideas why it is set up that way.
It turns out I am departing from A8. I told the agent that if I ended up at an A gate I didn’t mind walking back, but still she said it wasn’t allowed As you point out the rules are there for a reason (even if not always good reasons).