Originally Posted by
OH-LGG
ExpertFlyer's letters and numbers are useless and höpöhöpö:
Mostly AY U availability is 0 and upgrades are like roulette. Upgrades clearing or not clearing have nothing to do with EF numbers/letters.
Not sure there was sarcasm there but for sure U availability correlates between immediate upgrade availability or no. In cases where U0 weeks before flight anything can change, however.