Originally Posted by
kahuna613
I've just finished reading through this entire thread and am still not sure I am understanding mileage upgrades. I will shortly begin traveling to Europe and Africa several times a year for the USG, meaning (I believe) that my tickets will be Y-fare on U.S. airlines only, per the Fly America rules. In that case, as someone without any SWUs, am I able to upgrade using miles if I am flying DL codeshares in Y class operated by KLM or Air France? I will not be able to re-issue the tickets with AF or KL flight numbers.
You cannot take AF/KL O inventory on a codeshare; the ticket must be (re)issued on the AF/KL flight number to pull this award space. I am not familiar with Fly America, but you definitely cannot use a SWU on a codeshare without first changing to the operator's code.