ATLANTA, Georgia (CNN) -- Airports across the United States were experiencing flight delays Tuesday afternoon after a communications breakdown at a Federal Aviation Administration facility, the administration said.
The facility south of Atlanta was having problems processing data, requiring that all flight-plan information be processed through a facility in Salt Lake City, Utah -- overloading that facility.
The two facilities process all flight plans for commercial and general aviation flights in the United States, said FAA spokeswoman Kathleen Bergen.
The administration said there are no radar outages and said they have not lost contact with any planes. The roughly 5,000 flights that were in the air when the breakdown happened were not affected -- just those that were waiting to take off.
iReporter Stephanie McCauley sat on the tarmac for more than an hour at Baltimore/Washington International Airport Tuesday on a flight bound for Albany, New York.
"It happens. It's just weird because you're sitting and you don't know if it's going to be 20 minutes or 2 hours," McCauley said.
The possibility of the delays clearing up quickly didn't look good.
Cheryl Stewart, spokeswoman for Baltimore/Washington International Airport, said as of about 3:40 p.m. some flights were being allowed to take off, but the FAA was no longer accepting new flight plans.
On the FAA's Web site, delays were being reported at all 40 airports located on the administration's flight information map.
The worst delays were in the Northeast, Bergen said. Chicago's Midway and O'Hare airports were reporting delays of up to 90 minutes.
The Web site, which normally lists the length of expected flight delays, was no longer listing that information Tuesday afternoon.
The total number of flights affected was unknown, although it was believed to be in the hundreds.
Mark Biello, a CNN photographer sitting on a delayed flight at Hartsfield-Jackson International Airport in Atlanta on Tuesday afternoon, said flights there were being cleared for takeoff one at a time.
"They're releasing the planes, but on a one-by-one basis, so it's really backed the whole system up -- at least in the Atlanta area," Biello said.