Originally Posted by
SkyTeam777
Interesting, and the whole point of alliances is that it's seamless between airlines. How frustrating. They can check documents at the gate, too.
This isn't Alaska Airlines specific, every single time (pre or post-covid) I've done a US-domestic flight, connecting to some international flight, the domestic segment has only checked my passport and not the full documentation which was always checked by the international carrier.
This always runs the risk of being denied boarding mid-trip, so I often have a return flight booked for the domestic segment which is cancellable specially during covid times.