Originally Posted by ecaarch

A few years ago DL started allowing the use of Global Upgrade Certificates (GUC's....same as SWU) from virtually any fare class. But when that was implemented, DL also quietly changed the way that GUC's were processed. Previously, a GUC basically got you confirmed AT TIME OF BOOKING if there was a J seat available (and a spot on a waitlist on the rare occasions that a J seat wasn't available). Now, a GUC gets you onto a waitlist at time of booking. As travel date gets closer and DL has a handle on how many J seats will likely be unsold, DL starts releasing seats to thiose on the waitlist. It is pretty unheard of for GUC's to clear at time of booking anymore.

So in summary, GUC's went from heavily restricted but virtually guaranteed upgrades to a more widely accessible CHANCE of an upgrade into the leftover seats that DL hasn't sold. Each procedure s*cks, they just s*ck in different ways.