Delta has the same. Free same day confirmed flight changes for open seats, as well as free stand by, once you hit platinum/diamond/gold. I'd often use it to ma

Delta has the same. Free same day confirmed flight changes for open seats, as well as free stand by, once you hit platinum/diamond/gold. I'd often use it to make un-bookable connections where you land and immediately get on a plane instead of the required amount of transfer time, and get faster times to destination than you could officially order, lol. Also often just bought the last flight of the day and went to the airport whenever I felt like it that day and took the next flight out.