Originally Posted by
pbh220
1. Can one upgrade from Econ>Bz? Or only Econ > Prem Plus? ...
Either -- not all aircraft have PremPlus
Originally Posted by
pbh220
If "yes" then can one only upgrade to BZ/First from a PremPlus fare? ...
You can upgrade to Business / First from standard economy even if there is a PremPlus cabin
Originally Posted by
pbh220
2. PZ: can a Premiere Gold upgrade from Econ > Bz/First with this inventory code? ...
Yes from any paid fare -- except Basic economy can be upgraded.
Award flights can not be upgraded except by GS, by elites with certain Chase MP credit cards on CPU routes, and sometimes a cash offer at checkin.
Originally Posted by
pbh220
3. Will PZ inventory apply to a Refundable Econ Fare? ...
yes
Originally Posted by
pbh220
Appears UA has severely decreased upgrade inventory, yes?
Depends on the route but there has been a long term trend to offer less upgrade space as UA prefers to sell the seat or upgrades for cash