Originally Posted by
KARFA
For the T5B connection point, generally you can only use it if your onward flight is already showing a gate on B or C. If it is not showing a gate, or showing an A gate, then you are supposed to go to T5A to go through connections.
SOP is to push people to T5A but mainly to avoid confusing them with talk of tunnels and problems later if they board the transit instead. It’s perfectly possible and acceptable to use T5B regardless of departure gate or whether it has been published yet - telling them (politely) that you’re very aware where the tunnel is and how to use it is enough to get through.