How is the Fajr prayer performed on January 14, given that the journey was from America after the 'Isha prayer and I arrived in Germany after the Dhuhr prayer the following day, and the trip took about 8 hours with a 6-hour time difference between the two cities?

For travelers on an airplane, Fajr time is when the true dawn appears, and the Fajr time in the city of departure or arrival is not considered. If dawn breaks, prayer becomes obligatory. If they can perform the prayer on the ground before sunrise, they should wait. Otherwise, they should pray on the airplane according to their ability. And whoever does not pray it on the airplane out of negligence must repent, seek forgiveness, and make up the prayer immediately.