Originally Posted by
bevoinva
Correct. US uses the "O" booking code for preferred first class upgrades - not sure if this "O" booking class will accurately match up with that or not.
From what dstan was able to see, it appears to be spot on for Mileage saver awards though.
Yes, you're right - O includes Preferred Auto-Upgrades as well. (Originally had it in there, then deleted it, but will put it back in that post.)
On a related topic - has anyone ever missed an auto-upgrade at their window, with F inventory available, then gotten one subsequently? (This excludes a case where an F pax cancels at the last minute.) IME, I always get them at my SP window if there's an F seat available or not at all. So, I'm wondering if US dumps all of F into O at the CP window or if they still hold some revenue seats back?