Computers coordinating the flights operated by United Continental Holdings failed on Thursday for several hours, delaying United flights and stranding thousands of passengers.
Shortly after 7 a.m. Pacific, United acknowledged the problem via Twitter: "We're aware of a computer issue affecting some of our flights. We're working to resolve it. We'll update as we have more details."
About an hour later, United said the problem had been resolved.
For passengers who missed connections or never got where they were going, the effect of the computer outage is still being felt.
United did not respond to several requests for comment.
According to The Washington Post, United's technology troubles began in March, when it switched to Continental's passenger information system, known as Shares. United and Continental merged in 2010 but didn't start operating as a single entity until November 2011.
Like several other writers covering the travel industry, author Nicholas Kralev questioned United's decision to ditch its Apollo passenger information system in favor of Shares, calling it complex, clumsy, unintuitive and difficult to use.
At travel website Upgrd.com, a comparison of the Apollo and Shares systems has attracted a number of critical comments from people claiming to be current or former airline employees. One comment reads, "Let me tell you, as a person who over 32 years has worked on various airlines computer systems, the Shares [system] sucks!!!"
During the company's Q2 2012 conference call for investors in July, CEO Jeffrey Smisek reported on the company's first full quarter as a single airline.
"The Shares conversion was successful, but following the cutover, we faced a number of issues," he said. "As we identify these conversion-related issues, our top priority was to improve the customer and coworker experience by determining the cause and quickly deploying teams to fix the problem."
Smisek said the company had made significant progress on these issues in the second quarter and that customers calling the company's reservations line now experience normal wait and call handling times.
Significant progress however appears not to have been enough. Only a week earlier in July, a United computer glitch offered travelers $40 round-trip flights to Hong Kong. And the following month, about 10% of the company's 5,600 daily flights were delayed following the failure of a computer system at one of the company's data centers.
In the company's Q3 2012 conference call for investors last month, Smisek insisted that United continues to make progress integrating its systems with Continental's, but acknowledged that persistent problems have alienated some customers. "[W]e recognize that some of our customers chose to fly other airlines during the summer when our operational performance degraded," he said. "Just like when your preferred road to work undergoes construction, you might choose to take a detour until the road gets repaired."