Originally Posted by
Fabo.sk
I think you can enter Skytrain platform without passing security, but no going back. That would be the Z platform.
IAN-UK somehow entered A concourse to go to the A platform, which is unclean Schengen (e.g. landside) That would explain how he ended up at transfer security + exit control to enter non-Schengen part of B pier.
But the Skyline stop for B (Schengen) is completely landside and brings you down to the check-in floor among shops and cafes. You will then go through security and passport control in that order to B non-Schengen departures.
