The airline only needs to be physically shown a passport which will get the person into the destination: they don’t record it. So you book with the Czech passport, go through border control with the Czech passport, then show the airline staff the Russian passport.
At least some of them certainly do record it. I have multiple passports and have had difficulties several times with an airline that has one of my passports listed, that doesn't show the right of entry to the other country and which I was not intending to use for that flight. Moreover, if you are travelling on a codeshare flight, for instance, all airlines involved will record your travel documents, but only the airline operating the flight will be able to make updates to them.
edit: they certainly do not anywhere rely on eyeballing a piece of paper and letting some random staff member say "yup looks legit".
Is there a conflict between (a) wanting to exit a country using the passport you entered it on*, and (b) wanting to enter a flight using the passport you will exit on?
Some countries make the airline need to know in advance whether to let you even board. Say the US with the electronic visaless authorization. You gotta give the airline your ESTA. Canada wants to know as well. So you need to have your PR card or Canadian passport on file or the electronic authorization.
But that doesn't stop you from entering Europe on a European passport. You can have your say Canadian passport on file and fly out on that. At the destination you show your European passport (smaller line ups and basically you are just waived through). You never show the Canadian passport in the EU on arrival. You have the Canadian one on file and show that when leaving so they let you board. Back in Canada you use your Canadian passport to enter.
This way you never get any visa stamps and you "fly through passport control" on either end.
So yeah, even if this is maybe used by "sleeper agents" it's also just normal for dual citizens.
To the extent that the airlines care, anyone who cannot enter the country is deported at the airline's expense. So where it matters they do care.
This is not really new. Back when steamship was the most common way of traveling between continents, the ocean lines gave lessons to the third-class passengers on what to say to US immigration officials so that they wouldn't have to pay for their lodging and return if they got denied entry. (At the time first-class passengers were not screened this way, so they didn't bother teaching them.)
As both a US and EU citizen who lives in the EU, I actually run into issues with this. I book my flight with my US with my US passport, and it's a round trip, so it ends up with the same passport registered. I go through the EU line upon entering the EU, but they consistently also ask me for my US passport. This hasn't happened on the automated kiosks for whatever reason.
At the airports I've done this, they are separate checkpoints. e.g departing Australia for the US:
1. check in with the airline using your US passport. If it is the return leg of a flight from the US, you probably put in your Australian passport details when booking so you may need to go through an agent.
2. go through Australian border control checkpoint, and show your Australian passport
3. board the plane showing your US passport if asked for ID.
I may be wrong, but every time you do a check-in you are giving your information and they record it, and you have to show the same document at boarding time.
This doesn't mean that it must be the same document that you used to enter or exit the country though, although depending on the destination the airline may require proof that you can enter the destination country, like a visa or a passport, because having a passenger refused entry may be an hassle for them.
You can use a document to exit the departure country, another for the airline (with the caveat above) and another one for the destination, even with different names on them.
You would should both to the airline staff. "This is my ID I used, and this is my ID which allows me entry so you(the airline) won't have to bring me all the way back to my arrival point." Airline staff will not record this second form of ID: it's only to show the staff for a moment.
Okay, but spies, terrorists and tax evaders (or military duty evaders for Iran) with double nationality have been using the double-passport trick for over a century: Is it time that airlines feed their incoming passenger list to the destination authority?
I mean… isn’t that built-in to the system already? I never supposed entering Thailand that I wasn’t already known to the Thai border police, who surely must have checked that I’m not a banned and/or wanted criminal, right? Or is this system supposed to a single safety net of the destination’s border agent recognizing a fake passport just by checking the numbers in a DB? Is that why TPB’s founders escaped to Thailand, is this why Wolkswagen’s pollution manager thought he could cross the USA freely on holidays without spending 8 years in jail, is this why Carlos Ghosn escaped Japan?
Or do countries carefully avoid reaching an agreement on airline IT systems, just because they do need each others’ spies to cross freely?
It's not even a "trick". It's just normal for dual citizens to make things faster.
Leave Canada on Canadian passport. You just get nods and wave throughs. Enter European country on EU passport in the smaller line (or nowadays automated border control stations). Just scan passport, (don't) smile for the photo and off you go. Flying back Canadian passport is on file and the CBSA just asks you some basic questions and waves you through.
As far as I know if you're a citizen of a country, you have to use your passport from that country to enter/leave that country, at least it's that way with USA:
[1] > U.S. nationals, including U.S. dual nationals, must use a U.S. passport to enter and leave the United States.
And the German foreign ministry says it's international practice to do so, but says "should" instead of "must":
[2] > Bei Doppelstaatern (Erwachsene und Kinder) ist zu beachten, dass nach internationaler Übung
> - die Einreise nach und die Ausreise aus Deutschland nur mit deutschem Reisepass oder Passersatz, z.B. Personalausweis
> - die Einreise in und die Ausreise aus dem anderen Staat (dessen Staatsangehörigkeit die Betreffenden ebenfalls besitzen) nur mit den nationalen Dokumenten des anderen Staates
> erfolgen sollte.
Also a requirement for Canadian dual citizens [3]
I guess it'd be interesting if one has a EU passport but is entering the EU through another Schengen country (eg. A dual Canadian - Italian citizen flying from Canada to Germany). Logic says keep it simple and show the EU passport, but is there a EU clause somewhere that requires that?
Like I said, and this is personal experience: yes Canada needs your Canadian passport on file so they (and thus the airline) will let you board/back in.
I have been to several EU countries and none of them cared for the Canadian passport. Tried showing both at the beginning. They don't care. So we only show the EU one now.
Also funny: showing "the other passport only" because you don't have a current one. Like try using the Canadian one if you don't have a current EU passport (expired, never had one yet etc). Takes longer. Works too. Haven't tried recently so things might have changed.
Leaving an EU country has never required the EU passport. In fact having the Canadian on file is a requirement. Otherwise they call your name at the gate because you neither have a Canadian passport nor an electronic authorization on file and thus they can't let you board. So doesn't work in reverse nowadays.
For all the airline actually cares you should be able to just board a plane as long as you paid for the ticket ... everything else is what they are made to do or do because of (dis) incentives.
