ATLANTA --- An electronic communication failure Tuesday at a Federal Aviation Administration facility in Georgia that processes flight plans for the eastern half of the U.S. caused mass flight delays around the country. The Northeast was hit hardest.

But by early evening, the FAA said the situation around the country was returning to normal, with delays remaining in Atlanta and Chicago.

At one point, an FAA Web site that tracks airport status showed delays at about three dozen major airports across the country.

The FAA said the glitch appeared to have involved a software problem.

FAA spokeswoman Kathleen Bergen in Atlanta said there were no safety issues and officials were still able to speak to pilots on the ground and in the air.

She said she did not know exactly how many flights were affected, but she said it was in the hundreds. The FAA did not expect to have total figures until today.

Ms. Bergen said that in a 24-hour period the FAA processes more than 300,000 flight plans in the U.S.

Ms. Bergen said the problem that occurred Tuesday afternoon involved an FAA facility in Hampton, Ga., south of Atlanta, that processes flight plans. She said there was a failure in a communication link that transmits the data to a similar facility in Salt Lake City.

As a result, the Salt Lake City facility was having to process those flight plans, primarily causing delays in departing flights. FAA spokeswoman Diane Spitaliere said there were some problems with arriving flights as well.

Ms. Spitaliere said Tuesday's glitch appeared to be a software problem and the situation was returning to normal, though the Hampton facility was not yet processing flight plans again.

"We have our engineers looking at it, and we're doing a complete investigation," she said.

She said delays of 30 minutes remained at airports in Chicago while delays of 60 minutes remained in Atlanta, which was also experiencing weather issues.

A spokesman for Hartsfield-Jackson Atlanta International Airport, the world's busiest airport, did not immediately return a call seeking comment on the impact there from Tuesday's episode.

Ms. Bergen said officials at the Atlanta airport were entering flight data manually to try to speed things up.