I really don’t like codeshares, but I can understand the rationale for putting them together. It’s all about increasing traffic by putting two networks together, though the codeshare itself is just a way to trick reservation systems into putting those joint options closer to the top of the list. But not all codeshares make sense, and one of those, a tie-up between Frontier and Volaris, was just announced last week. I’m still struggling to understand the value.

On the surface, this shouldn’t be a surprising partnership. Indigo Partners owns Frontier and has nearly a quarter of Volaris as well. The company’s recent aircraft mega-order includes airplanes for both airlines. If the two airlines can cooperate, why not make it so? I’ll tell you why not. Because they’re supposed to be ultra low cost carriers (ULCCs), and a codeshare adds costs.

To be fair, both airlines are on Navitaire’s NewSkies reservations system, so technology probably isn’t a huge issue. There is still plenty of cost involved in now having to transfer bags between the airlines, settling up fare splits, and reaccommodating stranded travelers. It’s hard for me to know how much cost is actually involved in this, but the increase in complexity is clear. A pure ULCC probably wouldn’t be interested in this.

Maybe you could make the case that a big revenue opportunity would make this a worthwhile endeavor even for a ULCC. (I’d probably say that the airlines should instead be rethinking the routes they fly if they can’t fill their airplanes on their own.) But I have trouble even seeing how this can be a big revenue-booster anyway. Take a look at the cities Volaris serves in the US:

That is a lot of cities, but how many can actually be useful for a codeshare relationship? I’d imagine the biggest opportunities are in Denver, Las Vegas, and Orlando. Volaris serves each of those from both Mexico City and Guadalajara. (Denver also gets a weekly flight from Chihuahua. It had Monterrey service, but that appears to have just been pulled for this summer entirely.) Volaris can send people through those cities and then connect them to Frontier’s large operations in each to go beyond. Maybe those from Mexico City who need to get to Omaha will be thrilled. But what I’d really like to know is how much connectivity is even possible?

The beauty of a more business-friendly airline is that there are usually multiple frequencies in each market, so the options for connectivity are greater. For Volaris and Frontier, most of these routes probably aren’t even served once a day. The times don’t always mesh well either with many routes operating sub-daily and having varying flight times.

From the other side, Frontier today flies to Los Cabo, Puerto Vallarta, and Cancun in Mexico. Those aren’t big focus cities for Volaris. It would seem that the connectivity there would be pretty limited. This has to be more about flowing traffic through cities in the US.

According to the press release, Volaris expects to add 20 new destinations in the US and 80 new routes. I wonder how many of those can even be flown in both directions. I also wonder how many days of the week they’re even possible.

Let’s say that there is actually a good connection in a market. Take Mexico City to Little Rock over Denver, for example. Volaris flies Mexico City to Denver three times a week in early March, but then it goes daily and eventually settles back to just Saturday/Sunday in April. It bounces a lot, and so do the times with arrivals ranging from about 1030a to 1230p. Meanwhile, Frontier only flies Denver to Little Rock Tuesday/Thursday/Sunday in March. That flight leaves at 223p, so the times are good. (Let’s forget that it switches to Monday/Wednesday/Friday/Saturday in the morning in April.) Fine, so now we have a couple days in March where you can connect someone. But the return from Little Rock is in the evening, so it would require an overnight in Denver to connect.

Is that confusing? Of course it is. The schedules shift so much that it’s just luck of the draw if you find one of the few days that has a valid connection… in one direction. But let’s saying someone actually does find this and books it one way. What if someone takes the codeshare and the flight is late? How are these airlines going to reaccommodate that person? It’ll likely be an awful experience unless they want to buy a new ticket on another airline for the passenger. And that’s expensive.

I can only assumed this is some kind of arranged marriage, a forced coupling, at Indigo’s behest. But the opportunities for real revenue generation seem limited at best. Even if they do squeeze some revenue out of this, it’s hard to imagine how that could really offset the increase in costs and complexity.