My girlfriend is flying RDU-IAD-FRA-OTP in two weeks. Originally the flight from RDU is scheduled to arrive at 6:10. The original departure to FRA was at 6:59, and was moved to 6:49.

Is 39 minutes going to be enough? Are there any customs/immigration issues, or will she just have to show her passport as she boards? (In case it matters, she has a Candian passport.) Would 49 minutes have been enough?

There are some backup flights/routings if she misses that connection, but I want to avoid them as they add 3-4 hours to what is already a 13 1/2 hour trip.