A memory problem in the traffic management system of the Federal Aviation Administration resulted in the disruption of flights on the U.S. East Coast on Saturday, according to the agency.
The FAA said Monday that data was not removed from the flight control system even after air traffic controllers deleted it, until the storage limit was filled, putting demands on the processing power required for the smooth functioning of the overall En Route Automation Modernization (ERAM) system.
On Sunday, FAA said a recent software upgrade to a high-altitude radar facility at Leesburg, Va. had possibly led to the disruption, but did not provide details. It maintains that ERAM has had a greater than 99.99% availability rate since it was installed nationwide earlier this year.
The system replaced a 40-year-old En Route Host computer and backup system used at 20 FAA Air Route Traffic Control Centers across the nation.
A new function in the latest ERAM software upgrade lets controllers set up customized windows of frequently referenced data. The data was supposed to be completely removed from the system as controllers deleted it, which didn't happen.
FAA temporarily suspended the use of the function and is working with contractor, Lockheed Martin, to find a permanent solution. The contractor is also investigating why the problem was not identified during system testing.
The agency said Sunday that an automation problem had led to delays and cancellations at airports in the Washington, D.C., area on Saturday, with preliminary information indicating 492 delays and 476 cancellations.
Traffic at three major airports in the area dropped to between 70% and 88% of normal average traffic levels on Saturdays, after controllers fell back on backup systems and procedures.