Originally Posted by
Oakshadow
I guess I'm looking for the definitive rule on the OP's question. If you are booked on flights with non-DL ST flight numbers (KL or AF for examples) but your itinerary includes a US domestic leg on DL metal, are you eligible for an upgrade on that domestic leg? Yes the OP said the itinerary read not eligible, but it's not clear if that's an IT glitch that fell through the cracks and can be rectified at the airport or by calling the medallion line or if it is a set rule.
I'm thinking if its a DL fare Y, B, M, H, Q, K, L, U, T, E then you would be eligible for an upgrade but if it is another airlines fare (like AF W class or something like that) that you would not be eligible. You can always call and ask them to try and put you on the UG list though. I wonder if they can change the flight to the Delta coded number in the reservation and maybe that would help? It is worth a call to see.