Originally Posted by
BigPoppaCO
That makes sense; never thought about it that way. Are those the only 3 fare buckets that pull seats from PN class?
Yes, it's inline with the "premier instant upgrade" benefit (and so only works on CPU-eligible flights). As of the latest round of changes (which badly hit non-1Ks), other elite levels on Y and B fares can clear an Instant Upgrade into R if available, but are added to the upgrade list as CPU priority.
The only other group of fares which gets a complimentary upgrade to PN is all GS CPUs (any fare).