‍CHICAGO — United Airlines (UA) will temporarily take its core reservation platform offline early on February 4 as part of a planned “controlled restart” of its SHARES booking system, resulting in a short window where most customer and staff booking tools will be unavailable.

According to internal guidance shared with travelers and staff, the outage is expected to run from approximately 01:55 to 04:00 Central Time.

During that period, it will not be possible to:

• View flight schedules
• Make new bookings
• Modify or retrieve existing reservations
• Issue tickets, cancellations, or refunds
• Check in for flights using employee or staff travel portals, including myIDTravel and ID90
• Use some booking and check-in functions in United’s own internal and mobile tools

To reduce disruption, UA has proactively canceled most flights scheduled to depart during the outage window.

About SHARES

SHARES is the core reservation and inventory system that UA uses to run its bookings. UA adopted the system after merging with Continental, replacing the older Apollo system in 2012.

In practical terms, SHARES is the back-end platform that stores and manages:

• flight schedules
• seat availability
• fares and tickets
• passenger name records (PNRs)
• check-in and boarding data
• changes, cancellations and refunds

When you search for a UA flight on the website or app, an airport agent checks you in, or a travel agent issues a ticket, they’re all talking to SHARES behind the scenes.

The software began as a reservations system developed by Electronic Data Systems (EDS) decades ago and is now owned and maintained by US$4.4 billion-valued company Travelport, owned by the Elliot Management Corporation.

Unlike newer cloud-native airline systems, SHARES a highly customized, mission-critical mainframe-style platform that has been adapted over many years to handle United’s network, rules and partner airline connections.

Passengers Plan

The airline is advising travelers to plan around the downtime. Passengers with flights departing shortly after 04:00 CT are encouraged to check in before the outage begins, as online and app-based check-in opens 24 hours before departure.

While the interruption is short and scheduled during low overnight demand, it affects the core reservation database that powers availability, ticketing, and check-in. As a result, even basic self-service transactions will pause until the system comes back online.

United has not indicated any impact beyond the three-hour window, and flights outside that period are expected to operate normally once systems are restored.