Originally Posted by
warakorn
Thank you for the trip report!
Could you please quickly elaborate how you made it to this tunnel at FRA. This tunnel connects Terminal 1A/Z with Terminal 1B. The tunnel is Schengen and clean (after security).
Until now I was not aware of a direct pathway between Terminal 1B (either Non-Schengen Departure clean or Non-Schengen Arrival un-clean) to this tunnel. Because they is no direct pathway between either Non-Schengen Departure clean or Non-Schengen Arrival un-clean to Schengen clean.

I'm glad you brought this up because I was in exactly the same position yesterday.
I was in the LH FCL in 1B. I had a flight out of A a few hours later. The agent at reception said 'you shouldn't need more than 25 minutes to your gate.' I was puzzled by this because I also didn't think to use the tunnel, instead expecting to have to exit B completely, turn left landside, and go through security again for A.
No, she says, you just have to re-enter Schengen (escalator down from lounge, then escalator up again on the opposite hall), then take the tunnel to A. No security. I sat down and thought about this for a bit. When I left, I asked for detailed directions, but when I followed these I did not see any Schengen entry path that would lead to the tunnel entrance, and this is what all the security people told me.
If there is a way, I would love to know.