A More Detailed Look at United’s ConnectionSaver


It’s been truly enjoyable watching United’s rise from the extended depths of merger hell, and the airline’s recent roll-out of ConnectionSaver — though relatively minor in its impact — stands out as a visible hallmark of just how the airline has changed for the better. I spoke with Dave Kensick, Managing Director of Network Operations Control (NOC) to get more details on exactly how this program works.

The basic idea is quite simple. United wanted to automate the process of figuring out which flights to hold for connecting passengers. Up until now, it was using “connection planners” who sat in the NOC and used their brain power and experience to determine which flights to hold when connections were tight. The airline knew automation would help the airline to make a lot more passengers happy, so it went to work building the tool.

This was first tested out in Denver, a more simple hub in the sense that it’s largely a domestic connecting operation. In the early days, they ran a test versus the current manual system. The end result was that when looking at passengers with short connecting times, misconnects were reduced 30 percent. That’s a huge gain.

This was rolled out to Chicago in April. That added much more complexity. Not only was there a hub with a big international presence, but it’s a congested hub that is often going to be subject to ground delays/ground stops. It also has those nasty international inbounds that arrive at Terminal 5 sending domestic connecting passengers all the way back to Terminal 1. (And the train between the two still is down for service.) As Dave put it, they were trying to see if they’d break the tool. They didn’t.

United did make modifications after learning what O’Hare needed that Denver didn’t. Now the airline is ready to roll it out to Los Angeles by the end of the month. Houston will follow once they’re comfortable that Los Angeles is working well. Why does it take so long? Just as O’Hare has its quirks, every other hub has some as well. LAX, for example, has a lot of alleyway congested for airplanes pushing back and arriving, so United needs to consider that. The airline even puts people on the ground in the hub to evaluate and tweak as it ramps up.

How ConnectionSaver Works

The tool starts to run several hours before departure, and it runs frequently. It takes in all the flight and passenger details. (It even looks at people connecting to United from another airline’s delayed incoming flight.) It tries to successfully connect every passenger until it starts running up against the constraints that United programs. What are those constraints?

United wouldn’t give me the whole recipe for the secret sauce, but it did outline some of the things that are taken into account. The tool looks at hugely important issues like ensuring the pilots will have enough time to absorb the delay and still be legal to fly. It looks at airport curfews. There’s also a consideration of gate availability: will holding this airplane hurt people on an inbound flight that needs the gate? It will also look at downline connections. If a flight from Chicago is going to LA and a ton of people are connecting to Melbourne, then they won’t hold the airplane in Chicago and put that connection in jeopardy. It also considers expected flight times. Favorable winds = shorter flight time = more tolerance for holding.

This is all just the basic set-up, and it will evolve over time. Surprisingly, the tool doesn’t currently take into account the number of potential passengers missing a connection nor does it consider status levels or fare paid. There are plenty of additional variables that can be added to the system over time in order to refine the model and help more people.

In the end, the tool spits out a simple recommendation on whether to hold the airplane or not. The NOC can override that recommendation, and they sometimes might for large groups or issues with other extenuating circumstances. (Large groups apparently are flagged beforehand anyway.) But that’s a call made at headquarters.

At the airport, the gate agents are presented with a notification on the departure management screen and on mobile tools saying that the airplane can hold. For example, here’s what the agent would see for a flight to Fort Wayne that they’re willing to hold for four minutes past scheduled departure because it will still get there early.

The gate agents have a list of tight connections, and if those people make it by 11:45am, they’ll leave on time. If not, they can go over by four minutes, just enough time to let those last stragglers hopefully make it . But if they don’t, then they can’t hold any longer.

Because this is a fluid delay that may not even become a delay at all, it isn’t posted in flight status anywhere. You won’t know it’s happening from the outside.

The Stats

How has it been going so far? Since the beginning of the year — remember, only Denver had it operating in the first quarter — more than 15,000 people have made their connections thanks to this tool. But what’s most impressive is the impact on the operation, or lack thereof.

Only about 20 percent of flights that are held actually end up taking any departure delay at all, and the average delay is 6 minutes. In many cases, they are simply able to keep the door open a bit longer than usual and still push back on time. And of those flights that are delayed, only about half see an arrival delay since the other half make up enough time in the air. (In case you were wondering, checked bags haven’t impacted these numbers at all. The baggage coordinators know where to station bag runners in advance since they are connected in to the tool as well. The bags nearly always beat passengers to the plane.)

Here’s another interesting — but more concerning — stat. Of all the passengers for which United holds flights, only 90 percent of those make it on the airplane. What happens to the other 10 percent? Dave wants to know. Maybe they just assume they miss their flight and are going to a customer service counter. Or maybe something else is going on. But United is going to start playing with how it notifies people.

Customers today should get a regular connection email, but beginning this month in Denver, United will begin testing a “hurry up, we are holding your connection” note that will go to the traveler’s mobile to get them to make a run for it. They are hopeful that this will increase the percentage of people who make it.

Branding For the Win

Now, why is it that I say this is a great example of how different United is today? Isn’t that somewhat overstating this tool? Probably, but then again, not only did United have a team put together a great, customer-focused program, but it also had the smart idea to brand and market it at the right time. Usually the two sides don’t work well together. (Just look at how well Polaris was marketed WAY before it was ready.) This just feels like an airline with its divisions working together on the same team. At least that’s how it looks from the outside, and it’s a refreshing change.

Think about this from a Chicago perspective. In Terminal 1, you have United which has dramatically improved operational performance and is putting tools out there to make things even easier for passengers to make their connections. In Terminal 3, you have American which has seen its operational performance sag. It has also stubbornly stuck to this notion that airplanes must close doors early and depart on time at all costs. The internet is littered with stories of angry travelers. Is it a coincidence that United branded this and started talking about it once it got it working well in a competitive hub like O’Hare? I think not.

It helps when your competitor is going through a rough patch, but moves like this make it look like United is starting to step up. That, of course, is great news for the airline’s customers — more than 15,000 of them so far this year.

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42 comments on “A More Detailed Look at United’s ConnectionSaver

  1. Brett, even if I didn’t work here at United, your analysis of this new tool is refreshing to read.

  2. CF, Great article and congratulations to UA. I hope that the geniuses at AA are reading this.

  3. “What happens to the other 10 percent? Dave wants to know.” – maybe Dave’s gonna find out a whole bunch of hidden-city ticketing activity…

    1. …or these are PRM / wheelchair pax who are not being expedited to their connection. This highlights another possible integration point; notifying their PRM vendors that the plane is being held and the wheelchair runners need to prioritize service for passengers requiring assistance.

  4. How does this work with Cranky Concierge and other high-touch agencies?

    (Agencies that use EDIFACT of course — any plans to write up the TripActions or Amtrav NDC announcements from last week?)

    1. Jon – It doesn’t. Basically if there’s a mobile number in the account, they will alert that mobile number (or they’ll start testing it). That’s the only way to find out. So, if we put our own number in there, we would get the update and could communicate with the client, but there isn’t anything designed to actually alert the agent.

      And no plans on the NDC stuff, but it’s good to see it marching forward.

  5. This tool simply brings together information into one place that airlines like UA have had for years and proves the power of advancing technology to make decisions – but it is only groundbreaking because UA chose to put the effort into automating a major part of the decisions (or allowing machines to allow humans to make a well-informed decision) that are part of running a large connecting airline.

    The assumption here is that everyone has a cell phone and that UA can communicate with passengers individually regarding held connections. Do they adjust the departure times on gate information screens in the terminal?

    1. Tim – No, mobile phones are the only way to communicate. The idea is generally that people will run to make their connection and it will be there. You get less of the “sorry, door’s closed” garbage that makes people so angry. But they are just starting to play with the notification piece, and that is certainly going to be important.

      The reality is that posting on the boards wouldn’t be good, because most flights don’t even take a delay. They just need to figure out how to best communicate this.

  6. What a refreshing story to read.  I’m a United guy and have noticed a positive change at the gate as well as in the cabin.  I do have some tight connections coming up over the summer so I’m looking forward to how things turn-out.   Patrick Dee

  7. Very interesting. Your last paragraph is particularly salient as I was thinking the entire time I was reading it that there’s no way AA could implement something like this right now because of: 1) the level of dysfunction in their operations, and 2) the lack of buy-in and compassion from front-line employees. Great post.

  8. Thanks for the interesting wright up. A few questions… 1. didn’t UA have a policy where the aircraft door would close five minutes before departure? I remember that reading that somewhere. 2. What happens once the remaining hubs are added to the system? Adding SFO with the constant weather delays & EWR being as congested as it is, I wonder what tweaks would be required to make this system work properly & not have a meltdown. Also what is NOC?

    Thanks Cranky.

    1. SEAN – I don’t remember United’s exact policy, but yes, all airlines have a policy on when they close the doors prior to departure. This just gives more flex in those situations. For the remaining hubs, they wouldn’t tell me all the specifics, but they will tweak as needed to ensure it works.

  9. > Surprisingly, the tool doesn’t currently take into account the number of potential passengers missing a connection

    That is somewhat surprising if the goal is to get as many people as possible to their destination in a timely fashion. Especially if they potentially have bottlenecks (slots, taxiways …) and need to choose between two or more flights that can take a delay.

    Do they factor in how easy it would be to reaccommodate misconnecting passengers (no open seats for three more days, last flight of the night, only flight of the day etc)?

    In general, a great thing, but somewhat surprising that it took until 2019 for this to get developed.

    1. Oliver – I don’t think reaccomm is built into it yet. This is purely about just finding the slack in the system that allows them to hold briefly. It’s an ops tool that will eventually become a commercial tool, I’d imagine.

      1. Commercial tool? As in, text from United:

        “Hey Oliver, we see you are about to miss your connection. Sorry about the mechanical delay on your inbound. Would you like us to hold the flight to XYZ for a small fee of $10/minute?”


      2. I’m also confused by “Surprisingly, the tool doesn’t currently take into account the number of potential passengers missing a connection”. Doesn’t it start with this for all inbound connecting flighs? And later in the article you mentioned the tool considers downline effect and wouldn’t hold if the downline connection is impacted? Do you mean the other passengers who don’t make the gate hold, and/or those arriving waiting for the gate to free up?

        1. Cate – The tool doesn’t look at the number of inbound connections when making a decision on whether to hold a flight or not. It just sees if there is a tight connection and decides off that. The result should be the same whether there are 2 or 10 people connecting.

          For the downline effect. If the tool sees people connecting FROM the flight on to a another flight later, then it will be less likely to hold for those connecting TO the flight.

  10. Thanks for the great article.

    I’m curious how this affects gate agent performance review. I assume they don’t get dinged for failing to get the flight out on time when they delay it for this reason? My understanding is that at AA, gate agents are more or less required to prioritize D0 at the expense of all else. Any idea how this works?

  11. Cranky, this is monumental for United!

    If there is one thing that aggravates the daylights out of me, it’s walking up to a gate on a connecting flight, seeing the plane still there and jetway attached and a United agent saying, “sorry.” The worst for me a few years ago in Denver when I had a one-hour connection that became tight because United mis-loaded the airplane and we were delayed at ORD. When we arrived at DEN, we were told the plane for GEG had closed the door and it was too late. The gate was still attached and it was 10 minutes before departure.

    There were 13 people on the ORD-DEN flight headed for GEG. All were told, “we have you re-accommodated on our 7:00 p.m., departure.” This was at 8:30 a.m. As a 1K and someone who was pretty upset, I managed to a get VP for the Denver station to re-accommodate on a combination of a PDX and Alaska Air flight. But it never should have come to anything close to that.

    A couple of “Oscargrams” after this and a couple of other similar incidents and it appears Oscar and the gang at UAL are listening. For that, I am extremely grateful.

    Big question: What’s United going to do when you have five very tight connecting passengers from DCA to ORD going to SFO and there’s five standbys at the gate ready to go and waiting for a seat? Do you hold the plane for the confirmed passengers or do you book the stand-bys and move the tight connection?

    1. Dave – I am sure that they won’t have a system the prioritizes standbys over confirmed passengers. I can’t imagine it would take standby lists into account.

      1. I don’t think that’s really what he was asking. His question was this:

        Say there’s a tight connection onto a full flight and a standby waiting for a seat. You can hold the flight for the connecting passenger, but he might not make it, and by then it would be too late to board the standby–so the seat might go out empty. Or you could just let the standby have the seat and send the flight out full, on time. Which would happen?

        1. Grichard – I don’t know. But I would assume that they could still get the standby onboard if they were prepared properly.

        2. I would think you clear the standbys and have them stand on the jet way. If the connecting passengers make it then the standbys go back up and get rebooked. If the connecting passengers don’t make it, the standbys walk on the plane just before the door closes and sit down, saying a prayer of thanks. At least that’s how it could work for nonrev for sure.

          1. @Greg that’s exactly it. If a connecting/late passengers makes it last minute, the standby gets the boot if they are not on the plane yet.

  12. This is an excellent write-up of a promising use of data!

    Any idea what sort of parameters there are? Let’s say a flight departs at 3pm and the tighest connections are scheduled in at 2pm and are on-time. With no late inbounds I assume it will *not* scrutinize how long the 3pm flight can be held without serious impact and report that time the gate agent, yes? If that’s true, any idea how tight things need to be? If the 2pm inbound is delayed to a 225pm ETA will Connection Saver fire up? How about a 235pm ETA? A delayed 225pm arrival connecting to a 3pm departure is no problem for a seasoned, able-bodied traveler sitting near the front of the inbound. For a slow-walking travel novice sitting in the back row of a 737-900 they might well be in danger.

    On the flipside i wonder if there is a point at which they don’t bother listing a hold? If that 3pm has been determined to safely hold until 307pm do they bother issuing the hold advisory if the delayed inbound is estimated in at 2:50pm? 2:55pm? 3:05pm?

    I really love this — just curious how it functions. And very encouraging to see how they are rolling it out and (apparently) learning from experiences.

    1. Dale – I gave you everything they’d give me. They were somewhat tight-lipped and didn’t want to give away the secret sauce. So I don’t know any deeper details.

  13. As an avgeek who doesn’t work in the industry, I love articles like this. As much as people like to hate on the airlines, the amount of coordination, thought, and work that has to go on behind the scenes in the airline world (even outside of IRROPS, but especially during IRROPS) has to be incredible, so it’s great to read about things like this. Definitely look forward to reading more Operations-focused blog posts.

    I know flight schedules are booked months out, but minor tweaks to exact departure and arrival times are pretty common. It would be interesting to think about using the historical output of ConnectionSaver to plan ahead and tweak times, either a few days out (e.g., moving a flight’s scheduled departure from 1105 to 1115 a week before the flight if that flight is very often held a few more minutes for connecting pax, and almost always has extra slack in terms of block time) or using the system to help identify where United has opportunities to better optimize block time, flight schedules, etc…

    Tons of potential for this system beyond just the day-to-day tactical decisions that it is designed to support.

  14. 15000 people saved from missing connections sounds good.. But the interesting stat would be the ratio of “connections saved” to “connections missed”.. and then extended to “connections missed” to “total connections”.. An ongoing interesting graph as the program is rolled out across further hubs..

  15. So from my fortunately limited experience with connections on the United system how much extra are we going to have to pay for a connection that works?

  16. I am a UAL retiree, and delighted to read your report, and learn about this effective program. Of course as a NRSA I didn’t expect the program to help the standbys, but the screen display has ‘NRSA’ reight in the middle of the screen? Amazing! It includes help for retirees flying standby.


  17. Will be interesting to know, if possible, what they learn about the people who miss the held connections. People who are at the back of the plane? Who figure that their bags will miss the connection anyway and would rather wait? Slow walkers or passengers who need assistance? People who have to pee really badly and stop by the bathroom? Hidden city tickets?, etc. Not sure we’ll ever know the answer, but fun to speculate. Nice to see UA doing this.

  18. As a frequent flyer of United over the years, I am glad to see them improving across the board. The new Polaris business product is much nicer than the previous offering, and I actually look forward to having cocktails at the ORD Concourse C international departure lounge now. Current concern however, is they just stranded me in Bhopal (cancellation of the BOM-EWR run due to geopolitical heat along the flight path), but it may offer a nice diversion through Munich or Frankfurt on the way home. Looking forward to hearing Cranky’s thoughts on this new development.

    1. DannoH – I’m not planning on writing about the Indian cancellations as of now. It certainly has nothing to do with India, but it’s just all the airspace issues with Pakistan and now Iran in between. It just makes it too hard to run that kind of flight because of how much extra flying (and probably a stop) involves.

  19. Hasn’t saved sh*t for me. 1K MM. Always connect to/from United Express at ORD,DEN or IAH. Luckily they mis-coded my latest delay at IAH as crew and not weather so didn’t get any issue with hotel voucher.

    Flight before that, DEN gate agent was gleeful that she had closed gate (early) and would not reopen. Plane sat there for another 30 minutes.

    But you explained how it is supposed to work very well.

  20. Look at that sleek gate management interface UA uses. On the other hand, compare to AA still using a “QIK” screen developed in 1980. Sigh…

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