Flying outside of Schengen

[enzobordo]

Im planning to fly from Germany to Serbia and back. Does anybody know about whether it is necessary to land on international airports after crossing the borders?!
I would be very grateful for any tips ASAP.

[Jan Olieslagers]

Affirmative.

[rnzoli]

Some national airfields can arrange customs/border control with 24 or 48 PPR. For example, LHUD Szeged can clear you into Schengen zone when coming back from Serbia. After that done in Szeged, you can practicalky fly back to any airfield within Schengen countries.