An operational error during routine system testing of United Air Lines's computer system was the preliminary root cause of a computer failure that forced the airline to cancel and delay U.S. flights yesterday, a United spokeswoman said. The failure was in the computers used to dispatch flights.
In addition, during the recovery of those systems, United encountered unrelated hardware problems that delayed the restoration of services for about two hours, spokeswoman Robin Urbanski said in an e-mail to Computerworld.
Urbanski said the airline wouldn't have a final count of affected flights until the close of business Thursday. She added that United plans to run a close-to-on-time schedule Thursday. However, there may be unrelated delays in the Chicago area this afternoon because of potential thunderstorms, she said.
United said it canceled 24 domestic flights Wednesday because of the computer glitch.
The outage occurred between 8 a.m. and 10 a.m. Central Time, causing delays across the country. In total, about 268 domestic and international flights were delayed, United said. The average delay time was an hour and a half.
This is the second time this month that a computer malfunction caused significant delays in the U.S. On June 8, one of the two systems used by the U.S. Federal Aviation Administration to manage flight plans failed, causing flight delays and cancellations across the country.
Robert McMillan and Robert Mullins of the IDG News Service contributed to this report.