Originally Posted by NickP 1K

I hold UK and US dual - just had an issue where I have a tight offline connection and little time to do a passport verify (WN to AA). Normally I don't do an ETA and just show the agent my UK passport, with AA and others checking API status for Home Office ETA flag this is now a problem.

Based on this offline connection, I was risking being a NO SHOW for check in. So I applied for an ETA on my US passport, got approved. AA check in still did not work - 10 min later it did and boarding passes issued. Really wish ALL airlines allowed you to enter a second a passport.

For those asking why risk it: Last minute trip due to a family emergency, so had little other choices with less flight availability - low risk missing the connection offline