Originally Posted by ozweepay
No, the SFO-FRA hop has been in H every time. It was just the first hop, DEN-SFO that was flipping between W and Q depending on forces beyond my ken.
When availability starts to get tight, given the current way that the industry works (this is certainly not UA specific), you may see the counts in a particular booking code on a particular flight oscillate up and down (e.g. from 1 to 0 and back) very quickly - often several times per minute.
This happens because agents (and websites) are allowed to "hold" the inventory temporarily. Of course, what this means in practice is that all of the different systems get out of sync with each other. Believe me, we all share your frustration.