Originally Posted by
Travelergcp
Once the flights are under airport control day of departure you might be able to upgrade, as they can seat your anywhere they want without reissuing your ticket. Ask at the airport.
.
Best advice given here -- the airport has lots of discretion and their goal is to generate any additional revenue for the carrier. If there are seats available, you are likely to be able to upgrade. If they don't do it at the checkin counter, ask again at the gate.