Originally Posted by
WineCountryUA
Likely the uniform fare lettering for economy across *A created barriers in this exercise. Something had to give and it was Instant Upgrade. Not defending UA, UA has been adding new options over the years and in their wisdom it was time for Instant Upgrade to go, so it could offer these other options.
At least it is not what DL has done with its WN-like fare structure.
UA could easily have made changes without affecting *A "uniformity" (such as it is). They c
uld have divided Y/B/M in a different fashion, say M for E+ and domestic PP fares -- and then only done instant upgrades from Y/B ... or some other combination, without getting rid of instant upgrades altogether.