Originally Posted by
Goldorak
Hmmm, I don’t follow you on this one or I am missing your point. Paid upgrades with AFKL are only available at check-in. What’s available all the time is changing a Y or W ticket in a J one by paying the fare difference. But this not an upgrade in the sense OP is asking, as you are just buying J.
Changing a ticket to a higher class - regardless of the manner of doing so - is an upgrade. Whether done well ahead of time (including change fee and fare difference), by taking part in an upgrade auction (not available on AFKL), by responding to an offer sent by email, by responding to an offer made during OLCI, or by enquiring at the airport/lounge.
Even using Flying Blue miles, ahead of time, at the airport, or even onboard, can lead to an upgrade!
The OP seems to enquire specifically about upgrade offers at check-in - which, as you say, are only offered during check-in - but it should be self-evident that online check-in offers are only available during online check-in. Therefore, in case the OP thinks that this is the only mechanism, it seems worthwhile spelling out that that's not the only way that upgrades can/should be secured. Such upgrades may end up costing less, if offered, but they are not the only way to upgrade from Y to J.