Originally Posted by
vbroucek
OP was referring to recent hardening of border controls (as of Monday this week), so your experience is irrelevant. However, AFAIK, the hardening was for road borders and at this stage only for borders between Austria and Germany only.
So, for the OP - you should not see any changes at FRA airport and everything should be as used to be.
While the FCT use by the OP and OP's wife is highly unlikely to be disrupted by the current Schengen controls situation, the increased border checks are not limited to just surface transport crossings nor are they limited to just Austria-Germany trips. Flights into Germany from Croatia and Serbia have been getting more of an official "reception" at German airports too. And flights from VIE and even AMS have been getting more of a "reception".
The transit allowance and/or admissibility allowance of Serbian citizens into Germany for US-bound travels remains basically under the same conditions today as at this point last year.