Originally Posted by
bennos
I think there's the technical implementation and the user facing policy. The technical implementation (as far as I can tell, I don't work for Delta) is that upgrades must clear before the certificate expires, regardless of the flight date.
The user facing policy was originally the same, though a couple of years ago the policy officially changed to require the flight to complete before the certificate expired. However, there were numerous reports (including my own personal experience) that as long as the upgrade was cleared (ie: the ticket reissued) the upgrade would stick. More recently, maybe a year ago, the policy became pretty much universally implemented. I suspect this was to provide "consistency" to the flyer.
As I mentioned earlier, that policy has now changed again. Must fly before the expiration (as stated on the upgrade cert). I have also had luck getting them used beyond the expiration date in the past, but no luck this past Spring. If you have had luck recently, please post.