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What's All This Fuss About AA's 'Rolling Hub'?  
User currently offlineDoorsToManual From , joined Dec 1969, posts, RR:
Posted (10 years 10 months 3 weeks 1 day 20 hours ago) and read 5135 times:

Hi

Could anyone briefly outline the basics behind the concept of a 'Rolling Hub', what its advantages are over the traditional 'peak' model, and whether this is still in the experimental stage for AA at DFW and ORD?

rgds

14 replies: All unread, jump to last
 
User currently offlineElwood64151 From United States of America, joined Feb 2002, 2477 posts, RR: 6
Reply 1, posted (10 years 10 months 3 weeks 1 day 17 hours ago) and read 5011 times:

The concept of a "Rolling Hub" is basically this:

A "peaked" or "banked" hub has as many planes as possible pull into every available gate in fifteen minutes, drop off their passengers, pick up new ones, and each depart less than an hour later. This creates a traffic jam similar to the LA freeway at 5pm Friday afternoon.

So the idea is to bring in the planes a little at a time, building up to capacity. In the first fifteen minutes, only about a third of the available gate space might be used. We'll call it a "section". Over the next fifteen minutes, another section, and the next fifteen minutes, fill up the gates. This prevents an over-capacity situation on the runways and long approach patterns.

Then, over the next fifteen minutes, the first section of aircraft departs. Sure, some of the people from the most recent inbounds can't make connections, but they aren't scheduled for them, and there will be a flight later in the day, anyway. Then the next section leaves. Perhaps another series of flights will arrive to take the place of the first section. Then, as more flights arrive, the last section departs, and the process is already starting over again.

That's about as simple as I can make the model. Obviously, there is more to it than that, but this should help with a basic understanding of the concept.

Another way to think of it might be of "continuous operation". "Rolling" gives the impression of aircraft always moving, never with all aircraft stopped at gates.



Those who fail to learn history are doomed to repeat it in summer school.
User currently offlineKlwright69 From Saudi Arabia, joined Jan 2000, 2015 posts, RR: 3
Reply 2, posted (10 years 10 months 3 weeks 1 day 14 hours ago) and read 4885 times:

CO's operation in EWR has had a "rolling hub" set up for a while now.


User currently offlineDoorsToManual From , joined Dec 1969, posts, RR:
Reply 3, posted (10 years 10 months 3 weeks 1 day 8 hours ago) and read 4775 times:

Thanks for the information.

Does this form of 'continuous operation' maintain the number of flights per day at the levels of the previous 'peaked' model, or is there some efficiency gain - or is it merely a congestion thing?

rgds


User currently offlineHa763 From United States of America, joined Jan 2003, 3632 posts, RR: 5
Reply 4, posted (10 years 10 months 3 weeks 1 day 7 hours ago) and read 4736 times:
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DoorsToManual,

It does all of the above. You can easily maintain the same number of flights using a rolling hub instead of a peak hub. Yes, there is an efficiency gain. Instead of having employees sitting around and waiting between flight banks, they will be working because the flights keep coming in. Plus you can schedule less employees per shift during the former peak times. It also helps reduce congestion by spreading the traffic through out the day instead of only at certain times.


User currently offlineUal777contrail From , joined Dec 1969, posts, RR:
Reply 5, posted (10 years 10 months 3 weeks 22 hours ago) and read 4630 times:

Do any other airlines besides AA or CO use the rolling hub strategy?


ual 777 contrail


User currently offlinePSU.DTW.SCE From United States of America, joined Jan 2002, 7521 posts, RR: 28
Reply 6, posted (10 years 10 months 3 weeks 22 hours ago) and read 4605 times:

Currently, no.

The rolling hub concept also greatly increases aircraft utilization. Aircraft spend less time on the ground, and more time in the air. With a rolling hub, aircraft are scheduled with less ground time, basically enough to unload and reload, with a little cushion of time. Aircraft don't have to wait as long for the next bank. There isn't quite as noticable reduction in ground time at the hub, more so at the spokes, where aircraft used to wait until it was time to fly back and arrive at the next bank. For instance, AA at DFW was able to free up about 7 aircraft, I believe, and still maintain its same schedule when they switched over to the rolling concept.

The hub has to at least be a certain size in order to be converted over to a rolling format. At least 6-7 banks need to be scheduled in order to work in order not to compromise the network by reducing connection opportunies. Passenger waits would be too long in this case for the next flight to their desired city.

Hubs that could work in a rolling format: (besides AA at ORD, AA at DFW, CO at EWR)

NW at DTW
NW at MSP
UA at ORD
CO at IAH
DL at ATL


User currently offlineJjbiv From United States of America, joined Jan 2001, 1226 posts, RR: 5
Reply 7, posted (10 years 10 months 3 weeks 22 hours ago) and read 4595 times:

ATA and Chicago Express host a rolling hub at MDW from ~5AM-11PM...

joe

[Edited 2003-09-07 21:38:11]

User currently offlineN951U From , joined Dec 1969, posts, RR:
Reply 8, posted (10 years 10 months 3 weeks 21 hours ago) and read 4581 times:

Additionally, at DFW American was able to free up use of the B terminal gates for American Eagle's regional jets.

User currently offlineDoorsToManual From , joined Dec 1969, posts, RR:
Reply 9, posted (10 years 10 months 3 weeks 21 hours ago) and read 4551 times:

Thanks, I needed a little clarification after reading a slightly more academic description of the rolling hub concept in this month's Airline Business.

It was stated that this form of operations did lead to some connection opportunities being lost, so AA had to study which markets could lose connectivity for increased productivity, and to try and maintain some form of connectivity for more important flight/city pairs.


User currently offlineN951U From , joined Dec 1969, posts, RR:
Reply 10, posted (10 years 10 months 3 weeks 21 hours ago) and read 4538 times:

It was stated that this form of operations did lead to some connection opportunities being lost, so AA had to study which markets could lose connectivity for increased productivity, and to try and maintain some form of connectivity for more important flight/city pairs.

Yes, AA had to do this, but it didn't have a huge impact on connectivity. For example, people coming into Dallas from Los Angeles aren't going to connect back to anywhere on the west coast, likewise those flying MCO-DFW aren't going to connect to the northeast.


User currently offlineCedarjet From United Kingdom, joined May 1999, 8045 posts, RR: 54
Reply 11, posted (10 years 10 months 3 weeks 20 hours ago) and read 4506 times:

Not only do the aircraft spend less time parked at the gate like in a 'banked' hub schedule, but they also spend a lot less time in taxiway queues as the entire bank departs at the same time. I haven't been to the US since 9/11, and my memories of the queues for departure at Newark are not happy ones. If CO have spread the load a bit then thank god. Being number 41 for take-off (or worse) sticks in my mind as being typical.


fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
User currently offlineBoingGoingGone From , joined Dec 1969, posts, RR:
Reply 12, posted (10 years 10 months 2 weeks 6 days 18 hours ago) and read 4363 times:

The correct term is "De-Peaking". It's estimated that doing so will increase connection times by as much as 30 minutes, but that will be offset by increases in the number of round trips available to spoke cities by one or more per day, thus increasing utilization and capacity without adding an aircraft to the fleet, or offering the same level of service while reducing fleet size. Either way, it's a good thing as peak times at hubs are a nightmare for ATC.

User currently offlineElwood64151 From United States of America, joined Feb 2002, 2477 posts, RR: 6
Reply 13, posted (10 years 10 months 2 weeks 6 days ago) and read 4218 times:

I know it'll sound like I'm taking credit for something I didn't do, but I thought about this for a small airline, also.

Most small airlines, in this case I was thinking about Vanguard, try to give people peaked-bank connections, meaning they might have 3 or 4 banks and each city has 2 to 4 flights per day. So they try to connect people in every bank to every city in the bank.

But why? As stated above, there are some cities that one would not connect through. Again with NJ, few people are going to fly LAX-MCI-DEN. It happened, but it was very rare. Maybe 2 or 3 a month.

It might be more advantageous to use a de-peaked hub for smaller airlines. That way, the aircraft do not sit around not earning money while the big guys squash them with frequency. Sure, there are extended connection times and some lost connections, but it increases the number of flights the airline can operate per day and therefore the number of cities that can be served.

I submitted a plan for this type of operation to Scott Dickson, President and CEO prior to 9/11, and it looked like parts of it were going to be implemented in the fall schedule, after Reno was supposed to be added, which it never was. However, following 9/11, schedules were cut back and the ideas went out the window. By the time we were ready to go back to the type of ops we were going to implement in fall '01, in August '02, we were out of money and out of business.



Those who fail to learn history are doomed to repeat it in summer school.
User currently offlineScottb From United States of America, joined Jul 2000, 6707 posts, RR: 32
Reply 14, posted (10 years 10 months 2 weeks 6 days ago) and read 4196 times:

Actually, the airline which uses rolling hubs the most is probably Southwest. They schedule their aircraft to maximize utilization of flight equipment, gates, and personnel. And the fact that they have a large number of flights at several cities with frequent service to several destinations allows relatively convenient connections as a by-product. While they do not operate hubs, per se, the scale of their operations at PHX, LAS, BWI, MDW, HOU, DAL, LAX, MCI, BNA, OAK, SAN, etc. allows for a significant percentage of passengers to connect. Even smaller cities like BHM, MAF, LBB, or SDF have published connections. Scheduling flights according to resource availability, rather than maximizing connecting opportunities, is an important reason why WN is so efficient (and their costs are so low). As an example, US Airways uses 42 gates for 202 daily mainline departures from PHL; Southwest uses 22 gates for 182 daily departures at PHX. Having a large percentage of your traffic as O&D traffic at a given city also helps the economics of a depeaked hub -- given that fewer of your customers care about connecting opportunities.

The problem with a rolling hub lies with the potential loss of a few high-margin (i.e. at or near full fare) connecting passengers who might choose a competitor offering slightly shorter connecting times. With fewer of those around these days, though, it's arguable that the efficiency gains make a rolling hub a good choice for large operations line the ones cited above; I'd argue that UA at DEN, UA at SFO, US at PHL, and HP at PHX would also do well by depeaking.


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