I have a Schengen single-entry business visa. I have a meeting with my German supplier in Frankfurt and then I have to attend an exhibition in Madrid. Today I wanted to book a flight from Frankfurt to Madrid l, but I noticed a note from Latam Airlines when I was about to buy the ticket. The note that made a big confusion in my mind is as below:
The flight between Madrid and Frankfurt is considered an international flight (not Schengen); you must therefore go through Immigration. Make sure you have the necessary documentation: European Union ID, passport or multiple-entry visa, depending on your nationality.
What is this?