Eastbay1K says Certainly that's true in Business class - flying back from London in April, I was told my upgrade didn't look good because business was almost entirely checked in but was still overbooked by seven. However, I doubt they oversell First by very much. Most airlines are reluctant to oversell their top category, on the grounds that they're willing to upgrade passengers if necessary but loath to downgrade them. And don't forget, these are paying first class passengers we're talking about - the airlines definitely don't want to piss them off!