Just got back from Prague where we flew from Prague airport to Frankfurt to Chicago then to Knoxville, Tennessee.
We went through security at Prague before boarding. When we landed in Frankfurt we had a special bus to meet all of the Chicago-bound people on our flight. I thought this was rather extraordinary treatment to be picked up by the United Airlines bus and delivered to my connecting flight. Little did I know that the bus deposited us back into the airport where we had to go through security again. Now keep in mind the bus picked us up because we were on a tight connection and they only had 1 security checker for a whole room full of people. Neither did they have a metal detector to walk through...we all had to be manually wanded. What a huge waste of time that was! Then when we landed in Chicago they herded us through customs and then through security again. I'm astonished at having to do this 3 times. Just be prepared for long waits for security.