A computer glitch that disrupted airline traffic in some parts of the U.S. over the weekend was possibly the result of a software upgrade, the Federal Aviation Administration said Sunday.
The agency, which had earlier described a problem in its "automation system" as the cause of the disruption, said the problem could be possibly traced to a recent software upgrade at a high-altitude radar facility in Leesburg, Virginia.
The upgrade was designed to provide additional tools for controllers, the agency said. While the FAA and its system contractor complete their assessment, the new features have been disabled.
The agency said that there was no indication that the disruption was related to any inherent problems with the En Route Automation Modernization system, which it claims has had a greater than 99.99 availability rate since it was completed nationwide earlier this year. ERAM replaced the 40-year-old En Route Host computer and backup system used at 20 FAA Air Route Traffic Control Centers nationwide.
FAA said that the automation problem had led to delays and cancellations at airports in the Washington, D.C., area on Saturday, with preliminary information indicating 492 related delays and 476 cancellations.
The FAA brought down the arrival and departure rates in the area from 11 a.m. to 4 p.m. for safety reasons. That move resulted in about 70 percent of the average normal Saturday traffic at Baltimore-Washington International Airport, 72 percent at Ronald Reagan Washington National Airport and 88 percent at Washington Dulles International Airport.
FAA said traffic had operated smoothly on Sunday. It said on Saturday it was continuing a "root cause analysis" to determine the cause of the problem and is working closely with the airlines to minimize the impact on travelers.