Delta just made an announcement about the changes to the Same-day Confirmed-program that will take effect on April 23, 2013, and not for the better. You can read more about this on Delta’s website here.
Same-day confirmed has allowed Gold or higher SkyMiles members to confirm to a flight that is on the same date as the originally ticketed flight and to do this without any charges if done within 3 hours of the scheduled departure time of the new flight.
Now, the same-day conformed window is shortened to only 3 hours before or after your originally scheduled flight AND the same fare class needs to be available on your new flight. You can, however, do the request more than 3 hours advance, but it needs to be done before your originally scheduled flight.
The main limitation in the rule is the fact that the originally booked fare class needs to be available on the flight that the you would like to be confirmed on. Typically, the lower fare classes are not available on the day of travel and if you would like to get out on an earlier flight, you would need to stand by instead of being confirmed in advance.
Gold, Platinum and Diamond SkyMiles members can do same-day confirmed outside of the 3 hour window, but for the $50 fee that is applicable for all. Note that the same fare class needs to be available.
Delta just changed the police regarding the death & SkyMiles (you can read more about it here) and more changes are coming to the SkyMiles program shortly that will likely have a greater negative impact to the frequent fliers that this same-day confirmed change.
The main benefit of this program has been the ability to confirm the change for later or earlier flight without any charges for Gold or higher members. It has been beneficial if you have been able to wrap up your meetings early and could just hop on to an earlier (confirmed) flight back home.
This change doesn’t mean that you couldn’t get on earlier or later flight without any fees, but you would need to fly stand by and likely would not clear to business, as stand by’s are only cleared after all status based upgrades have been allocated.
I have only used this successfully once, when I overslept. The other time, when I tried to use it, all the flights out of Tampa were oversold and I just ended up buying a new ticket on Continental.