An operational error during routine testing of United Airlines' IT system was the root cause of a computer failure that forced the firm to cancel or delay many of its US flights earlier this week.
The failure was in the computers used to despatch flights, the company said. During the recovery of those systems, United also encountered unrelated hardware problems that delayed the restoration of services for about two hours, a spokesperson said.
Urbanski said the company planned to run a near normal schedule for a day, but that there could be short, unrelated delays in Chicago because of potential thunderstorms.
The outage occurred between 8am and 10am US central time on Wednesday, causing delays across the country. In total, 268 domestic and international flights were delayed, by an average of an hour and a half.
This is the second time this month that a computer malfunction has caused significant delays in the US. On 8 June, one of the two systems used by the US Federal Aviation Administration to manage flight plans failed, causing flight delays and cancellations across the country.