Next week, in the early hours of Wednesday morning, United Airlines will be taking most of its systems offline for a controlled restart and cutover window for their SHARES reservation system. Here’s what they’re telling their own travelers internally,
On February 4, 2026, from approximately 01:55-04:00 (Central time) United will be going through a major system update that will involve an outage of our Shares GDS. During this time, it will not be possible to see flight schedules, book travel, retrieve existing bookings, perform ticketing transactions, perform cancellation and/or refund transactions, or check in for flights using myIDTravel or ID90 Travel, as well as United’s own employeeRES or United app tools.
United has already pre-canceled most flights that depart during this time period. We strongly encourage staff travelers to plan in advance for this outage if they will need to travel on United, and book early. Additionally, we recommend checking in before the outage begins (check-in is open up to 24 hours before departure using the United app), especially if travel will commence shortly after the outage ends.
Some other communications show the window as 1:30 a.m. to 5:00 a.m. rather than just 1:55 a.m. to 4. It’s framed as a “technology upgrade which will restart our systems” to maintain “better functionality and reliability.”
With the reservations system down, United.com and mobile app, call centers, kiosks, travel agency channels and partner airline access are down during the window. Departures are paused during the window, but already-airborne flights continue. There’s no:
- Schedule display
- New bookings
- Reservatoin retrieval or servicing
- Ticketing
- Cancellations/refunds
- Check-in
In terms of the different anticipated timeframes, that’s likely a function of the hard downtime for the host system (“no transactions accepted”) versus a longer period for re-opening different channels in stages.
United hasn’t said exactly what they’re doing, and their IT architecture isn’t something I’m expert in. One possiibility is moving host systems and you’d want a clean transaction stop during the cutover. If they’re upgrading database layers, messaging systems or batch schedulers or tightly coupled systems around SHARES they might schedule a restart window.
The goal they’re promoting is better functionality and reliability after the controlled restart. But United has said more about its SHARES passenger service system transformation work more broadly.
- gradually moving systems and logic into cloud
- seat maps are a starting point – legacy systems were fragmented:
“Seating at United was complex, with 30+ applications managing seat assignments.. [and seat maps/assignments are] embedded in every part of the PSS.
- moving away from old flat files, with “90% of code/business logic in assembler” and rules scattered across multiple applications and interfaces
They’re trying to move away from mainframe and green screens into cloud architecture. After the outage, though, we may have more clues abotu what United has done.
- It was mostly infrastructure/reliability. No feature or interface changes to united.com, and potentially fewer errors online or dealing with agents.
- A step towards offer-order merchandising changes in how flights and prices are shown to customers
- MileagePlus In United’s earnings call they signaled major changes to the frequent flyer program in coming weeks, so this could be preparing for how that’s handled.
A planned restart/cutover that takes SHARES reservations capabilities offline for a few hours may just be ‘operational resilience’ whether from a new system environment or better redundancy setup. But it also may be more, and we’ll start to know mid-next week. If any readers are familiar with the details, I’d love to learn more.
@gary “you want to learn more”
you’ve already nailed the key takeaway
get out of assembler = get off big iron
why: the 6-digit hexadecimal pnr limitation goes away when the last line of TPF code is sunset
what is that?: the ACP/TPF (Airline Control Program / Transaction Processing Facility) was written I believe in 1962 and 1963 by IBM and as the world of technology evolved, the functionality written on top of and within “assembler” and “flat tiles” continued to be “distorted” to accommodate the restrictions and requirements of TPF
translation: we can’t post links on your board, but the appropriate video on youtube is found with this search…
Tron defeats Sark and the Master Control Program
United is hitting on all cylinders. Best app. Strongest airline IT.
When will these boobs abandon the Prehistorically horrible Shares?? I’d was brought to United by the cheap trailer park Continental because it was owned by them after they bought/merged with Eastern. Yeah, it’s just THAT OLD. And they trashed the FAR SUPERIOR United reservation and flight management system for this piece of garbage. I recall the weeks of outrageous cancellations and delays when they first implemented this wasteful ineffective trash. You’d think they would have scrapped it long ago but NOOOOOO they keep trying to fix a terribly broken system. Cheap as the day is long. UAL under Continentals “leadership” lost a lot of its main travelers “Global Services” because Shares screwed up so many things! Continental didn’t want to pay for the far superior data management systems United had because they were leased systems!!!! But they worked far better and were living systems always being updated and improved by the contracted supplier. United is run by cheap Imbeciles to the bitter end.
DL went heavily to cloud computing which was part of the reason the CrowdStrike failure was so bad.
Any time you use a single vendor, you expose yourself to higher risks.
I doubt if DL exclusively uses CRWD and I doubt if UA will use a single vendor for cloud protection.
and UA provides lots of information but that doesn’t make it a better app.
I don’t know of any other airlines that allow anyone to see their standby lists and their seat map after departure.
The thing is that the longer you add kludges to an old system, the more expensive it gets to maintain in the long run.
Oh goodie. I’m sure this will go well. Reminds me of Anatoly Dyatlov at Chernobyl forcing the ill-advised test of the reactor. “Safety first. Always.”
I will be somewhere over the Atlantic when that happens heading into LHR. Hopefully it doesn’t trash the system. Glad I am not leaving LAX on Wed 2-4!
Ironically, I think the reason United’s app is so good is because Shares was clunky & CAL was focused on cost. They used the app to let the customer manage their own travel and be less dependent on customer service agents to save money.