No, Delta's site isn't glitching; Redeeming upgrade certificates has officially changed

The next time you search for a flight on Delta's website, you might be surprised.

That's because top-tier SkyMiles Medallion elites will now see much more domestic and short-haul international upgrade availability than before.

The Atlanta-based carrier has made changes to the confirmed upgrade process, and it impacts how flight results are displayed. But, it's not without its drawbacks.

Let's dive into the details.

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Changes to Global Upgrade Certificates

On Feb. 1, Delta made sweeping changes to how Global Upgrade Certificates (GUCs) work. As a reminder, Diamond Medallion members can select GUCs from the Choice Benefits package when qualifying for status.

The good news is you can now use them for last-seat availability on domestic and short-haul international first-class flights. The full region definition includes flights within the 50 U.S. states, and those to and from Canada, Mexico, the Caribbean, Bermuda, Central America and northern South America, excluding Delta One flights.

Additionally, GUCs now have last-seat availability for long-haul Premium Select recliners. So if there’s a seat for sale in premium economy, you can use a certificate to upgrade. This is far easier than how GUCs used to process, where upgrade space was often sparse.

But, the major caveat is that GUCs can no longer confirm an upgrade from coach into the Delta One pods on three-cabin long-haul flights — they'll only bump you up by one cabin.

Those booked in Main Cabin now upgrade to Premium Select on long-haul international flights. Flights with two cabins will still clear into Delta One, and Comfort+ is still treated as Main Cabin in terms of upgrades. Likewise, those booked in Premium Select can use a GUC to upgrade to Delta One.

Once an upgrade to Premium Select is confirmed, elites will be added to the Delta One upgrade waitlist 24 hours prior to departure, so there’s still a chance of a double upgrade — but it can no longer be confirmed at the time of booking.

For more details about the changes, check out Delta's chart below, and our comprehensive guide.

Much more domestic upgrade space

While Delta is tweaking how upgrades work on long-haul flights, it's opening the floodgates for availability on shorter trips. As mentioned, GUCs can now be used to confirm an upgrade on any domestic or short-haul international flight with first-class seats available for sale.

There are no limits to the upgrade inventory — if there's a seat left for purchase in cash, you'll now be able to instantly confirm the upgrade using a GUC.

This move has caught some long-time Delta Medallion members off-guard, as they're seeing lots more upgrade availability when searching for domestic flights.

Until earlier this month, Global Upgrade Certificates would book into a separate upgrade inventory for first class, which didn't always mirror how many seats were left for sale.

Now, if there's a seat left for sale in the forward cabin, it's yours to confirm with a Global Upgrade Certificate.

What happened to Regional Upgrade Certificates?

While Delta is making changes to Global Upgrade Certificates, it's not tweaking how Regional Upgrade Certificates (RUCs) can be used.

Regional upgrades — another one of the Choice Benefits options — can exclusively be used to upgrade domestic and short-haul international flights. These certificates continue to pull from the same inventory as before the Feb. 1 update, and as before, are not always available for instant confirmation.

Historically, Diamond members who pick both Regional and Global upgrades as part of their benefits have chosen to use the former for shorter flights and kept the latter for long-haul trips. After all, why redeem a Global Upgrade Certificate on a short domestic flight when you can instead use it to confirm a premium cabin on a much longer flight?

Now, Diamond members need to consider the differences in upgrade availability when making this decision.

Related: How to not 'waste' your Delta upgrade certificates

2 types of domestic upgrade availability

When Diamond travelers are logged into their account, Delta's website will display two different types of messages regarding upgrade availability for certain flights.

The first "First available with Global Upgrade Certificate" means that there's a seat left for sale in first class, and you can instantly confirm the upgrade using a GUC.

The second "First available with Upgrade Certificate" is the more traditional way that Diamond members have historically redeemed upgrade certificates. This means that you can apply a Regional Upgrade Certificate (or RUC) to your flight.

Saving your upgrades for long-haul flights ... or not

Many Diamond members will continue to choose to redeem their regional upgrades for domestic flights and keep the global certificates for longer trips.

If you're searching online for a domestic or short-haul international trip that's available for confirmation with a GUC, but not with an RUC, that means there are seats left for sale in the first-class cabin, but there's no regional upgrade inventory available at the moment.

You can purchase the ticket and then contact Delta's reservation department to add yourself to the upgrade waitlist using your RUC.

Of course, you could instead choose to redeem a Global Upgrade Certificate to instantly confirm the seat, but those certificates are more valuable, so you might consider holding those for long-haul trips.

That said, there are definitely times when the price difference between coach and first classes on a domestic flight is steep. In some cases, first-class lie-flat pods on select transcontinental or Hawaii routes can exceed $2,000 each way.

If you scored a deal for an economy ticket, redeeming a Global Upgrade Certificate to instantly bump into first could be a great deal.

Bottom line

Delta has revamped the upgrade process, and with it comes some major improvements to availability.

Unfortunately, the changes are largely negative for those who redeem Global Upgrade Certificates on long-haul international flights — now they can only be used to confirm a bump from coach to premium economy or from premium economy to business class.

But, there's good news for those traveling domestically or on short-haul international flights: Global upgrades can now be redeemed for the last-available first-class seat. Of course, using a Global Upgrade Certificate for a short flight might not make sense, assuming that you can find a better use on a long-haul trip.

You can instead choose to waitlist for a regional upgrade on a domestic or short-haul international flight, but then you'd be at the mercy of the upgrade gods.