Operating successfully on the Frankfurt – Stuttgart (since May 2001) and Frankfurt – Cologne (since May 2003) routes, the cooperative AIRail Service ("train to the plane") by Deutsche Lufthansa AG, Deutsche Bahn AG, and Fraport AG, also started serving the Frankfurt – Siegburg/Bonn route at the beginning of November 2007. According to the "seamless travel" principle, travelers check in at the central train stations to receive the boarding passes for their onward flight from Frankfurt Airport. (At the Stuttgart and Cologne stations, the check-in counters are at the train station; at Siegburg/Bonn, an automatic check-in machine is located at the DB Travel Center).

Upon arrival at FRA's long-distance train station AIRail passengers have to check in their baggage at the LH baggage drop counter in the AIRail Terminal. Vice versa passengers arriving from a flight and traveling onward by train can claim their baggage at the AIRail Terminal.

The AIRail Terminal is located directly adjacent to FRA's long-distance train station. Having baggage check-in and baggage claim directly at the AIRail Terminal significantly contributes to the convenience of passengers making their way through the terminals to and from the aircraft.