Originally Posted by
croberts134
Given the timing, I'd say UA cancelled the G class fare.
Most airlines, including UA, file their fares through ATPCO. ATPCO has a domestic submission at 1000 ET and the fares usually take 30-45 minutes to distribute to selling systems. It makes sense if you saw a fare pricing out at 0945 ET and then it was gone at 1100 ET, but the class was still open.
This is the source of the urban myth that the best time to purchase airfare was early Tuesday afternoon. The theory was that airlines would publish sale fares on Mondays, other airlines would match on Tuesday, and then you'd get the broadest possible sets of discounts on Tuesday afternoon before inventory started to disappear.
While this may have been true for a while, airlines caught on, and airfare changes much more rapidly these days.