Delta quietly posted on its airline partner page that its loyalty partnership with Hawaiian Airlines will be ending on June 30. This is no surprise, but it would seemingly put a little hole in Deltaʻs network. Or does it? Interisland partnerships donʻt matter nearly as much as they used to, and I ended up deep in the weeds looking at how this market need has shifted over time. How deep? Well, this is going to be a two-parter.

Currently, Delta travelers can earn both redeemable and elite qualifying (MQDs) SkyMiles on Hawaiian interisland flights. They can also use SkyMiles to redeem for interisland travel. The third unrelated part of this is a codeshare where Delta puts flight numbers on Hawaiian’s interisland flights.

Hawaiian has long been the conduit for airlines to get better service in the islands to connect to their mainland flights. The big three US carriers haven’t operated interisland since the early 2000s. Once Aloha went away in 2008, that left Hawaiian as the only significant operator, and it was happy to take everyone’s feed. American, Delta, and United all have relationships with Hawaiian today. American’s ties will strengthen since Hawaiian’s new owner Alaska is not only a part of oneworld but also in a tighter relationship with American. But Delta will go in the opposite direction.

Once Hawaiian purchased Alaska Alaska purchased Hawaiian, the writing was on the wall for the Delta relationship to end, or at least be scaled back. After all, Alaska did promise to keep interline agreements with existing partners in order to sway the government not to challenge the merger. On the other hand, Alaska and Delta have been locked in a fierce rivarly in Seattle for more than a decade, and there was no way that Alaska would want to help its former friend if it could avoid it. Now, changes are coming.

So what will happen? A Delta spokesperson says that “just the mileage accrual piece” will end, though it’s clear on the website that mileage redemption also goes away. In the unwinding process, only tickets booked before June 30 and flown before April 1, 2026 will earn miles. Award redemptions can be booked by June 30, but they canʻt be changed after that date. (They can be canceled and refunded though.) The codeshare will continue for now, which should mean that people will still earn miles on those Hawaiian-operated flights booked with a DL code, at least for now.

This creates a very weird relationship. How often have you seen an airline have a codeshare partnership but no loyalty agreement for flights marketed by the partner airline? It wouldn’t surprise me at some point to see this turn into a pure interline arrangement, or whatever is required by the agreement with the government.

What else can Delta do? Not much. The only other airline flying interisland is Southwest. It is now slowly gaining the ability to interline, so maybe that’s a possibility in theory. But the frequency is much less, plus… Delta and Southwest are not exactly best friends either. Besides, Southwest would probably rather concentrate is interline discussions on those international partners that provide more value. Delta may just be out of options.

Then again, perhaps this doesn’t really matter much to Delta anyway. Does interisland not matter anymore now that there are more flights from the mainland to the neighbor islands? After all, it used to be that nearly everything routed via Honolulu and then fanned out to the Neighbor Islands. Now, there are plentiful nonstop to the mainland from the three other main islands. Just look at this chart detailing the rise of flying outside Honolulu.

Seats from US Mainland to Hawaiʻi

^{T-100 Data via Cirium}

I asked Delta hoping to get some more color here. I had dreams of an in-depth discussion, but instead all I got was:

We don’t have anything additional to share at this time, but appreciate you reaching out.

Well, ok then.

So, I pulled up Cirium data and started looking for answers in the data. I will share all of that with you in tomorrow’s post.