Comparing Delta and United’s competitive hub capacity

Curiosity got the better of me this weekend with respect to the capacity Delta and United Airlines have on flights from their own hubs to those of the other. And so I compiled a bit of data. I’m sure there are a couple errors in there as reading the timetables are a pain given the variation in aircraft and times throughout the week, plus I just picked a random week 10 days out, but I still think that some of the data is interesting.

Of the hub list only NYC is shared by the two (UA mostly at EWR; DL mostly at JFK & LGA) and that presents some interesting bits of data. Looking at seats from NYC to United hubs has UA winning without much trouble.


Comparing NYC to Delta hubs presents the same story, just told the other way (except for Chicago, where UA runs flights to both LGA and EWR from ORD) (not actually a DL hub; ignore that line in the chart).


For the rest of the airports Delta is mostly in the dominant position in terms of seats flown. No surprise in Atlanta, for example.


Nor in Detroit, Minneapolis or Salt Lake City.




Seattle used to be something resembling a United focus city and Delta is building it up as a hub but United still has more seats to most of its hubs than Delta does. In this regard it is something of an outlier in the data.


And then there’s Cincinnati, a station Delta still calls a hub despite having mostly eviscerated the capacity there. United has more lift than Delta to many of its hub cities there.


So that’s some of the data, but I also happen to wonder why it is this way. Why does Delta have more lift to United’s hubs than the other way around? The short answer is that I have no idea, but I do have a theory. Generally speaking United’s hubs are bigger cities with more potential passengers which means a higher load of folks who are starting or ending their trip in the hub rather than connecting onwards. To make their hubs work Delta needs more connection traffic to fill the long-haul planes. MSP has 46% connecting passengers, similar to EWR as of 2012. Houston Intercontinental was around 53% in 2013. LAX was much lower at 38% in 2011.


For Atlanta the number of connecting passengers is even higher, hovering near 70% in recent years. While that is expected to decrease slightly as Southwest changes its market strategy it should be noted that AirTran was already below the average which means Delta’s numbers were higher than that.


Going back a bit further (it turns out that finding this data was harder than I hoped) to 2005 the numbers are even more dramatic; there is a lot of connecting traffic over a lot of Delta’s hubs.


And so the ultimate question: Is one business model necessarily better or worse? Is having more flights to your competitors’ hubs a necessity to succeed? I’m not quite convinced. If your business plan is more focused on connecting passengers versus O/D markets then it absolutely is necessary as you need to funnel those passengers through your hubs to fill planes. But if you’re filling planes without the connecting traffic then it might not be so bad.

Pending more spare time in the future I’m planning to add the AA hubs into the mix to see what those numbers look like. I’m betting they mostly follow the trends of the last chart here, with a few minor changes. The hubs more dependent on connecting traffic will have more feed for connecting flights. It makes sense that they would.

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Seth Miller

I'm Seth, also known as the Wandering Aramean. I was bit by the travel bug 30 years ago and there's no sign of a cure. I fly ~200,000 miles annually; these are my stories. You can connect with me on Twitter, Facebook, and LinkedIn.


  1. You may want to consider IAH instead HOU. IAH is a much larger airport and is a United hub (but sadly not Delta). Delta service to/from HOU sucks.

    1. HOU includes both Hobby and Intercontinental in this case. That gives Delta more seats than it maybe deserves. Similarly CHI includes both ORD and MDW, also to Delta’s benefit. NYC includes EWR, LGA and JFK.

  2. I had done the analysis for ATL a while ago and I was very surprised with results. It was amazing that UA, only sent one 737 to ORD and the rest was RJs. At that time they hadn’t open ATL-SFO. Amazing that UA will give up competing in ATL.

    1. This is one of the main points I’m raising, though, Nic. Is United really not competing? How many of the passengers Delta carriers between Houston and Atlanta are connecting onward elsewhere versus just going to Atlanta? If we assume that the average holds in that market then 70%+ of the 1875 are connecting. How many is United (or Southwest) just carrying non-stop to the ultimate destination? Delta may be pulling lots of connections and United still “wins” the competition by carrying more nonstop elsewhere.

      Delta’s hubs operate at higher connectivity levels. That’s one type of competition. But it is different from what United does.

      1. Interesting theory, but following your logic you are saying, although UA has more non stop flyers, they don’t like to fly to DL hubs? 🙂
        If we look at United capacity IAH-TPA compared to IAH-ATL, does it make sense?
        If you can find numbers for lets say DL ATL-CHI vs UA ORD-ATL, do you think UA numbers are bigger?

        1. I have ATL-CHI numbers for both carriers; DL is much larger. Because they have WAY more connecting passengers in ATL than UA does in ORD. That’s the entire point here.

          ATL isn’t a top 10 market from Chicago and vv. ATL is the top market from MDW but the total number of passengers is still less than any of the top 10 from ORD.

          1. I meant the non conecting, so for Delta lets say 30%*2325=697 on the ATL-CHI, that is more than 100% of UAs seats to ATL. I am sure this is widespread.

            That is why I was saying UA doesn’t want to compete on Delta hubs.

  3. Very good points, but the one thing missing is the difference in passenger experience.

    Delta went to great lengths to make sure its large RJs are as close to mainline as possible, with f and wifi.

    For nyc-atl, UA flys 50 seaters (except 1 larger rj) vs all mainline for DL. If you were a 1K traveling for business, does it make sense to fly in a 50 seater RJ vs delta mainline? DL beats on frequency and mainline will likely have a better on time rating than a 50 seater into ewr.

    If I were UA, I’d try to get a CR7 or a E175 on most of these frequencies quickly.

    1. The in-flight experience is definitely different. But, again, it comes to where the passengers are actually flying and who they are. If it is people connecting over a DL hub versus a non-stop on UA then the comparison is less about UA’s RJs to the DL hubs than it is about the mainline non-stop option. Similarly, of course, someone flying from a DL hub on a non-stop is getting the benefit of mainline service versus connecting on a lesser quality UA RJ. In those cases, of course, Delta very much wins. But I’m not entirely certain that comparing RJ to RJ directly on those routes is really what the question should be.

    2. (Afterthought…)

      And I’d definitely agree (and I think UA does, too) That getting more 70 seaters in to the fleet is a great idea, but they’re stuck with long contracts on the 50s and they’re dealing with that.

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