Are United Airlines employees authorized to ask TSA screening questions?

Flights to the US have been subjected to additional checks for quite a few years now. Can't quite remember if that started after the shoe-bomber attempt or after the liquid bomb scare.

In many cases:

• There can be separate check-in areas for flights to the US, with additional questioning/verification before getting access to the check-in area;

• There is very often additional questioning/verification at the gate, before boarding.

The additional checks may involve:

• Documentation, including passports, visas, ESTA, etc. (CBP-related)
• Security questions (TSA-related)
• Additional searches of your luggage (TSA-related)

Of course, all this cannot be done by CBP or TSA officials abroad (except, for some of them, in airports which have CBP pre-clearance), so they are performed by local personnel working for the airlines. In many cases it's outsourced to security companies (the same kind of people you may see manning the general security checks), in some it may be handled by airline personnel / ground handling companies. Or it could be a combination of both.

In some situations, if you have already been subject to those additional checks before check-in (at the same airport), they'll place a sticker on your passport or some other identifying mark which lets them know you've already been checked by someone they trust to have performed the correct checks (and possibly, someone who is accredited to do so), and this will reduce checks at the gate (though not necessarily eliminate all of them). If you're in transit, this is a lot less likely, and you're bound to be checked again at the gate.

The short answer is that it has become routine. It's been some times that I haven't seen a flight to the US without extra screening (systematic questioning in the waiting line before check-in and random additional hand luggage screening at the gate) above and beyond the regular document check and luggage screening you can expect for international travel outside the Schengen area. I have experienced this for US-bound flights leaving from multiple airports and with different airlines (it's not specific to United or Frankfurt).

I don't see on what basis it could be forbidden and I am pretty sure that you don't have any effective recourse or any practical way to avoid it.

Note: the airline isn't (really) legally a Delegate of the far-end country requiring documentation and vaccines; when you land, the entry Immigration/Customs of the country still do those processes again themselves.

for example, the airline cannot jail you if they detect fraud; those are rights/duties of Countries, not corporations. They will REFER you to the National authorities, of course, if available.

ANSWER: Airlines (and ships) do this because per International Treaties governing transit across borders, THEY are responsible for TRANSPORTING YOU BACK if you are denied entry at the other end of the flight. So they do this to save themselves that expense.

What has happened to you is something more and more frequent, even more so since the pandemic began and the US entry restrictions.

From what I've been able to read, in many cases the airline is obliged to confirm that it has the required documents to enter the United States (TSA precheck or ESTA or US visa, even the passport!!).

With the arrival of the coronavirus, the airlines and their staff are also authorized to confirm extra requirements: PCR tests, vaccination proof, proof of having overcome the disease).

Although I understand your anger at the situation, it is something legal and can't be resorted to or avoided. If you are asked TSA evaluation questions, you will have no choice but to answer.