This plane didn't land at the big intl airport in Frankfurt, rather a smaller airport out in the sticks. Hahn was an US base, I believe.
Ryanair may fly scheduled flights out of this airport at Hahn. I know some budget carriers do. Passengers are bussed in. Maybe about 1 hour drive west of Frankfurt with no direct autobahn connection.
Was this a non-stop from Ireland or was their a scheduled stop at Hahn?