^ Atlanta, because of geography, gets to be sort of a double-hub, because in addition to its normal hub-shed of, say, a 600 mile radius (its distance to Chicago or Miami), it also serves as a hub for about two dozen airports across Caribbean island destinations that are far away enough that they would normally have their own hub in their own vicinity. The closest of the small Caribbean islands (USVI) is 1600 miles from Atlanta, and the farthest one (Trinidad) is 2200 miles away. Normally that type of distance would cause a separate hub to exist locally rather than being served from far away, but these are scattered little islands, and there isn't a critical mass of population or commerce or development to support a local hub, so Atlanta gets this outsized "hinterland". Also, being Delta's main southern frontier hub, a similar phenomenon happens with Mexico and Central America, for about 20 destinations. As a southern long haul gateway, there are another dozen or so destinations in South America.

Compared to those southern routes, O'Hare can't have a similar number of Asian destinations just because of sheer distance and therefore traffic volume, and Canada traffic is intrinsically small. For Europe flights, Atlanta looks like it enjoys status as Delta's largest hub, or is roughly tied with NY, while O'Hare appears relegated as UA's 3rd-biggest Europe hub (with New York and Washington DC being better positioned) and as maybe AA's 3rd-biggest Europe hub (with its east coast hubs being better positioned).

So, a lot of this results just from how the hometown airline(s) of a city have chosen which other cities will serve as their other hubs. Another part results from Atlanta being very well situated for both Europe as well as Latin America and the Caribbean, which have much more traffic than Asia. Of course, the eastern seaboard has a huge population, and the South is booming in population, to begin with.

that's an interesting explanation thanks

Someone over at airliners.net compiles this every year and I always find it pretty interesting, so I thought I'd share it here. It compares 2016 vs 2017 international service in the summer peak season.

^ Thanks for posting!

The T5 extra gates can't come soon enough.

So it seems this summer will see the kickoff of the Boeing 797, with a couple hundred orders anticipated and UA as a prospective launch customer. It's to be a long-contemplated middle-of-market aircraft, replacing the discontinued 757 and to some extent 767, addressing the market between the 737 and 787. It won't be in service until the middle of the 2020s, but it seems they have taken a leap of faith and decided it will be a twin-aisle. This is a little curious since it is probably less fuel efficient than a slender, long aircraft, and also starts getting close to overlapping with the 787. Airbus is already mocking this decision, though it could just be sour grapes. A twin-aisle would board/deplane faster, but the jet is targetted to routes of like five hours or more, so those benefits would be overshadowed by the fuel inefficiency.

For the guys here familiar with airport operations, are longer fuselages more gate-constrained and short wider jets easier to assign to gates, or to taxi? (And I wonder which type would have the broader wingspan?) Trying to understand airport-related factors driving the widebody decision. Looking at gate inadequacy issues at ORD for example, it seems wingspan is a bigger problem than length, but I'm not really sure. Glad though that the new T2 project will be able to take all this into consideration.

bloomberg.com/news/articles/2017-03-07/united-looks-at-boeing-s-paper-plane-and-likes-what-it-sees

T3 Concourse L expansion - American Airlines
 

https://s27.postimg.org/affoy335v/Sc...0.24.12_AM.jpg
https://s27.postimg.org/79v37vkjn/Sc...0.24.21_AM.jpg

Wow! Can't wait to see it. We haven't visited to Chicago for a long time.

Concourse L Expansion
 

Thanks for posting. I've been looking for concepts of this but I couldn't find any. How many gates will they have, or will they have only the additional 4 in the rendering?

It is going to be a long walk for connections now. After thinking about it, I'm wondering why AA didn't want to use more of the existing L concourse and have the new gates for the low cost carriers at ORD.

5 E-175 gates

AA is footing the bill so it's for their use.

L gates
 

Thanks. That'll be a long connection from some of the gates in the G, H or K concourses. Anyone know if there will be moving sidewalks? Speaking of sidewalks, I was surprised United removed them from T1.

Indeed it is. They already removed it a while ago. They won't need it anymore. Because the those children were playing the moving sidewalks.

If the rendering is accurate, that's going to be a narrow apron alleyway between concourses.

Concourse L extension
 

ORD = O'hare Regional Destination

Are these new gates only capable of handling American Eagle planes? And does this kill any chance of ORD ever having a T4? The OMP over a decade old had this whole area being wiped clean for a T4 for One World. Over 20 years ago AA used about 1/2 of the G concourse for regional planes. Then it went to all of G and a few gates in H, K, and L. And now they are adding this L extension. UA did the same thing in T1/T2. They once had only part of the gates in T2 for Express, but now it's all of T2 and most of the gates at the end of the C concourse and after gate B17. Remember when UA had every gate in T2 for mainline with 727s, DC10s, 747s? Same thing for the B and C concourses.

I don't have the specifics, but ORD has to have a higher % of regional jets for a large hub than any other city in the world. Pretty sad when I think of ORD from the 80s and early 90s. It's Delta too. NWA flew DC10s and a 747 to MSP, Delta flew several wide bodies a day to ATL.

While it's certainly true that airlines don't fly the size of planes they used to, capacity is still considerably higher today than it was when they did. Consumers decided they would rather have hourly 737 flights between cities instead of far fewer DC10/747 flights. Airlines have also historically lost absolutely tons of money but are now printing money.

Also RJs are not what they were in the 00's. 50 seaters are quickly being parked in favor of larger planes. (not 747 larger, but 80+ seaters) ORD was certainly the king of RJs but as the 50 seaters are rapidly phased out, ORD also stands to gain the most by the semi-reversal of that strategy. It's the main contributor to why O'Hare passenger traffic grew faster than any US other airport in 2015.

And also why in 2016 we lost out to LAX, with ORD instead of also gaining it just kept its pace). UA and AA regional seats are way down due to one regional going bankrupt. If you check the amount of seats regional lost at ORD in 2016, that equals almost the amount LAX beat us by(mainline picked up some of the slack only because they had no choice). Also ORD, although it has more international carriers now lost it's share of International traffic coming to the USA compared to the 80's and 90's. International hub buster aircraft(787/A350/777X) will in the long run do the same to LAX.

Presumably the 777-8 is a "hub buster" but not the 777-9 ? Ie, because the 777-8 is basically like a 777-300"ULR", where the 777-9 is just a 777-300ER with three extra rows of seats and not much more range. Anyway I wonder how the new generation of aircraft will play out for ORD international routes.

More international destinations but less capacity to the international megahubs that can now support non-stops to 2nd and 3rd tier US cities. LHR being the most obvious example.

Is there any chance that Southwest one day could be a financier of another Ohare terminal as Midway is about operationaly maxed out.

I think this is in the realm of possibility these days. Southwest's aversion to high landing fee/congested airports is a thing of the distant past. The rise of discount international carriers servicing Europe and Asia could make natural feeders for them as well.

^ But aren't profit margins on these flights pretty thin? Especially since they have no business class. ORD landing fees are high and rising.

I wonder what routes would make sense even if isolated at ORD away from their MDW hub.

Unless it were kept to the same scale as Spirit and other discounters at ORD, UA and AA would scream bloody murder about this.