-- A computer system that tracks aircraft flight plans failed Tuesday, triggering hundreds of flight delays across the East and the Midwest.
It's unclear why the system failed. Officials said Tuesday night that they are investigating the cause.
Flights at large hubs such as Chicago's O'Hare and Atlanta's Hartsfield-Jackson were delayed 90 minutes or longer while Federal Aviation Administration employees manually entered flight data into computers, FAA spokeswoman Laura Brown said.
The systems that follow planes on radar and allow controllers to communicate with pilots operated normally and no flights were endangered during the failure, Brown said.
The agency estimated on Tuesday evening that hundreds of flights had been delayed by the glitch, which happened shortly after 1 p.m., Brown said. The problem was worsened by severe weather, including tornado warnings, near Atlanta.
The delays fell far below the numbers seen on days when thunderstorms strike broad swaths of the nation, causing thousands of flights to arrive late, according to FAA data.
Eric Greenberg, traveling from Boston to Washington, D.C., arrived more than an hour late.
"It's a call to action for these guys to get the right resources and infrastructure in place," he said.
When the FAA's computer system, located near Atlanta, went offline, a back-up system in Salt Lake City began processing flight plans. However, the secondary system could not handle the sudden increase in volume and fell behind, said Hank Krakowski, FAA's air traffic chief. The system feeds flight plans to FAA's main radar system, which monitors flights across the country. The FAA cannot allow a jet to take off without a flight plan.
The decades-old computer system, which has experienced problems several times in recent months, is slated for replacement soon, Brown said. Carriers want the FAA to accelerate completion of the new system, said Basil Barimo, vice president of the Air Transport Association, the large airlines' trade group.
Delays were heaviest at O'Hare, Hartsfield-Jackson, Chicago Midway, Boston's Logan International and Baltimore/Washington International Thurgood Marshall Airport, Krakowski said.