Hi everyone,

I am Indonesian, and will go to Medellin through Madrid with these details:
Jakarta - Madrid on Etihad landing at T1
Madrid - Medellin on Avianca at T4S
gap between land and departure = 7 hours
I don’t have an Schengen visa

How reliable is the on-request airside T1 to T4S bus? I don’t mind the 30-40 minute wait I read here, just need to make sure it works.. Is there a guide somewhere as to how this exactly works? Thanks!