Hello!

I'm trying to book flights from the US to Seoul and back, most likely with Asiana since we're a UA Gold family and UA is not offering good options for our routing. I'm looking for help to understand the difference between the different economy fares.

When booking, I see the following options: Promotion, Special, Saver, Smart. What is the difference between these fares, especially for change fees, refunds, and seat assignments? I've spent over an hour trying to find an easy-to-use source that explains the differences between these fares, but I've found essentially nothing. The closet thing I've found is that if I do a dummy booking, there's a T&C link in the passenger details section. But when I read through this, it seems like there's no significant difference between the fares.

The only other thing I'll add is that I'm trying to buy the Economy Smartium upgrade as well.

Thank you!