Originally Posted by
ioto1902
Not quite sure about that.
Usually, op-ups are decided after check-in is closed (about an hour before departure) and are based on your status (to make explanations short), simply because they need to know exactly how many pax to upgrade.
Even when the flight is super-over-booked, the op-up list is prepared ad-meritum.
I'm not sure either, but it has been mentioned on here before and does have some logic.
Op ups are done locally, so sometime after the flight goes to being airport controlled at T -24 hours.
Historical figures/local knowledge can tell the controller that the flight will definitely be overbooked in Y.
Nothing to stop him/her bumping up a safe amount of pax, confident in the knowledge that it won't come back to bite them, in order to save time the next day.
Who is going to be op-uped? The gold already checked in on-line or the gold not yet checked in?