American Airlines' Reservations Change

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The world's biggest airline faces its biggest merger-integration test this weekend, when American Airlines Group shifts its US Airways unit onto its reservation system.

The new American has been preparing since it was formed 22 months ago for the complex information-technology fusion, a step that has gone poorly for some rivals. United Continental Holdings, which merged in 2010 and made the system transition in early 2012, disrupted passengers and employees alike for weeks. US Airways and America West Airlines, which linked up in 2005, executed poorly on their IT transition two years later.

Like Delta Air Lines's successful 2010 effort to move Northwest Airlines onto its reservation system, American has been taking a gradual course.

US Airways' frequent flier plan was folded into the larger American AAdvantage program in March, a step that went smoothly. The US Airways cargo, revenue accounting, and employee- and retiree-travel functions already have been switched to American versions.

American in July started transferring reservations made on US Airways for travel on or after Oct. 17 using American's flight codes and to its Sabre reservations-system provider, reducing to near zero the number of reservations that will need to be shifted in the final hours. In July, American also stopped offering a US Airways schedule beyond Oct. 17, forcing passengers to shift bookings to American, which also helped.

On Oct. 17, the final day of the switch, US Airways will handle about 200 fewer flights to its three hubs, or 11% less than usual. These flights were canceled months earlier for that very date, to lighten the load.

Maya Leibman, American's chief information officer, said earlier this week that her team phased in the changes to put "less stress and burden" on the system and on employees. "We have really tested the heck out of everything," she said.

The alternative is the so-called "knife-edge cutover," the approach United took. In that, all systems--governing separate frequent-flier programs, websites and reservations--are switched on a single day to minimize passenger hassles.

"Nothing gets much more risky than that," Ms. Leibman said. She figures the phased plan has reduced American's risk by up to half.

But there are no guarantees. Airline reservation systems enable all the steps customers take--buying tickets, changing seats, checking in, boarding and being reunited with their luggage. The software that runs check-in kiosks, gate readers, airline agents' computers and flier apps all connects to the reservations system. "This is a wildly complex process," Ms. Leibman said.

If problems arise, she said, the goal is to "triage and remediate as quickly as possible."

To that end, American in recent months has hired 1,900 new airport and reservations agents. For the transition period, it raised airport staffing levels by more than 20%. It is deploying 350 technicians to airports, deputizing 500 employees to be responsible for their airports' readiness and temporarily assigning American airport agents to US Airways hubs to assist.

The US Airways agents, who were accustomed to another reservations system, have been trained on a new check-in system that has been configured to look familiar but will be based on Sabre.

American Airlines founded Sabre in 1960 to automate its booked reservations. Sabre expanded to serve as a distribution system for travel agents in the mid-1970s.

Long spun off by American, Sabre now provides reservations systems to more than 80 airlines world-wide, and sells technology and software to the travel industry. In the U.S., beyond American, JetBlue Airways and Virgin America  also use Sabre for their reservations.

The Southlake, Texas-based Sabre referred requests for comment to American.

US Airways relies on a system called Shares for its reservations, which is also used by United Continental Holdings.

American's big switch will be run from a command center near its headquarters in Fort Worth, Texas. There also will be 23 satellite offices, including one at Sabre's reservations database in Tulsa, Okla., Ms. Leibman said. The centers went live on Oct. 14 and are expected to stay open around the clock until Oct. 27. About 1,000 people will be part of that effort.

The hope is that fliers will hardly notice the computer transition--but one element of the weekend's shift will be very visible.

When the last US Airways flights depart Friday night, employees will begin removing and replacing the remaining US Airways signage at airports, including on roadways and curbsides. When the first planes land Saturday, almost everything will be branded American.

The US Airways website also will go dark, after automatically directing visitors to aa.com, and the US Airways mobile app will be disabled by Oct. 18. A single set of travel policies and elite frequent-flier benefits will be in place come Oct. 17.

American started sending emails to its AAdvantage members reminding them that they should check on terminal and gate locations before leaving for the airport.

Ms. Leibman said she couldn't put a price tag on the testing and preparations. And even if this weekend's switch goes smoothly, the integration won't be over yet.

Other IT assignments planned for the next several years include a single flight-operations system, unified pilot and flight attendant scheduling systems and a combined computer program for mechanics, she said.

Write to Susan Carey at susan.carey@wsj.com