Originally Posted by
xyzzy
The empty seats on the seat map mean nothing. Some passengers have no seat assignments. If there are zero seats to sell then there will be no seats left for upgrades. The route you are on is one with very little chance of an elite upgrade.
I do believe, in my heart
, that premium passengers without seat assignments are more likely to no-show than passengers with seat assignemnts, all else being equal. I've seen it a handful of times on flights I was on that were sold-out in F with a few unassigned seats, and invariably a bunch of upgrades cleared at the gate.
Once the flight checks in full, it becomes much more difficult to get the upgrade. (Hope for a misconnect or a bad traffic jam...)