Just changed this week from DE-citizen/US-LPR to DE/US-citizen and trying to read up dual passport travel... *confused*.

Recommendations on various web-pages say to provide passport of destination country during check-in because airline wants to make sure you are allowed to enter the destination country. I guess because airline otherwise has to pay for carrying the denied passenger back ;-) And to just use local/right passport of the country you're entering/exiting for entry/exit-immigration checks.

But how does this work with third party country: I only have CN visa in DE passport (not enough time to get a new one on US passport). So i need to enter china with DE passport (and hope they can enter during check-in DE passport without it getting into tourist VW exit tracking problems). But what to use on the way back ? I definitely want to use DE passport to leave CN so they have correct exit-tracking (do not want to make it look as if i had overstayed). But also need to use US passport for them to know i can enter US.

Web pages make it look as if immigrations has nothing to do with check-in, but that sounds strange in the time of electronically networked systems. And i am not talking about fragmented bureaucracies like DE/US, but countries like CN: If i check in with US passport in CN, but then use DE passport on CN exit-immigration, would that not cause confusion/problems with linked tracking systems ?

I guess it would be easier to understand if i would understand what data exactly can be entered by agent during check-in. I know in DE/US how they can deal with DE passport + LPR(GC) status, but no idea if/how they an enter two passports.

Oh well, i will just show both passports and ask and hope for the best. I do have Global Entry and will get it updated to add the US passport before the trip, hope hat helps to eliminate issues on the US side... Or not ;-) ;-(