Originally Posted by
ung1
They do this on the very rare occasion, such as out of ATH where loads were miserable til they got rid of the second daily flight. But usually, it would be what eightblack said - fare difference.
They even did that in late April when the second flight was already out of the way - the offer for an upgrade Y->J was 150 EUR and J->F at 200 EUR. Hardly the fare difference (I believe), but this offer was only valid for the ATH-DXB sector. I guess several people had used the J->F upgrade as the F cabin got full while only 5 seats had been reserved the day before.