A computer problem with the system that collects airlines' flight plans is causing widespread flight cancellations and delays across the US today.
It is the second time in 15 months that a glitch in the flight plan system caused delays.
FAA spokeswoman Kathleen Bergen said she doesn't know how many flights are being affected or when the problem will be resolved.
Another FAA spokesperson, Paul Takemoto, said the problem started between 5:15 a.m. and 5:30 a.m. EST. The outage is affecting mostly flight plans but also traffic management, such as ground stops and ground delays, he said.
Regarding flight plans, airplane dispatchers are now sending plans to controllers and controllers in turn are entering them into computers manually, he said.
"It's slowing everything down. We don't know yet what the impact on delays will be," Takemoto said.
An AirTran Airways spokesman said there's no danger to flights in the air, and flights are still taking off and landing.
However, spokesman Christopher White said flight plans are having to be loaded manually because of a malfunction with the automated system.
"Everything is safe in the air," he said.
Hartsfield-Jackson Atlanta International Airport, the world's busiest airport, has been particularly affected.
AirTran had canceled 22 flights and dozens more flights were delayed as of 8 a.m. EST. Delta Air Lines also has been affected.
The FAA said in a statement that it is having a problem processing flight plan information.
"We are investigating the cause of the problem," the agency said. "We are processing flight plans manually and expect some delays. We have radar coverage and communications with planes."
Passengers are being asked to check the status of their flights online before going to airports.
Only minor delays were being reported at metropolitan New York City area airports, according to the Port Authority of New York and New Jersey.
Flight plans are collected by the FAA for traffic nationwide at two centers — one in the Salt Lake City area and the other in the Atlanta area, Bergen said. She did not know which center was affected Thursday.
In August 2008, a software malfunction delayed hundreds of flights around the country.
In that episode, the Northeast was hardest hit by the delays because of a glitch at the Hampton, Ga., facility that processes flight plans for the eastern half of the U.S.
The FAA said at that time the source of the computer software malfunction was a "packet switch" that "failed due to a database mismatch."
AP