A friend told me the story of how he was on an AF flight in Y, saw some free seats in PE, approached a cabin crew, asked how much the upgrade was, paid and spent his trip in J.

Is that really possible on AF? I know Emirates does that (or at least did in the past, not sure about now), and apparently also Swiss - but AF and KL? How would that work? Would they give away seats that were not available for upgrade before departure through the "on the ground" channels (website, call centre)? For money, for miles? At what rates, same as if pax upgrade before departure? And how would they deal with fare classes that are not eligible for upgrade? And how do they deal with not having loaded enough catering? And - this to me seems the real showstopper - what will they do about all the employees who have brought some cheap chocolate to the CDC in exchange for a seat up front?

I mean, if they barter Premiere seats like tihs, I'd be seriously interested, assuming the price is right.

I wonder whether he just invented a story, or mixes up airlines... just curious.