A major computer glitch triggered huge flight delays and cancellations across the United States Thursday as airlines were forced to input flight plans manually, officials said.

The problem detected in the automated system based in Atlanta, Georgia was repaired within a few hours, a spokeswoman at the Federal Aviation Administration confirmed, without giving any details of how many flights were affected.

Another FAA spokeswoman, Diane Spitalieri, told AFP the problem was "system-wide" and had been "slowing down the system significantly."

NONE The system is based at Hartsfield-Jackson Atlanta International Airport, Atlanta, one of the world's busiest serving over 90 million passengers each year.

It was one of the worst affected hubs as passengers and airlines across the East Coast braced for further chaos even after the system was up and running again.

As of 1400 GMT, AirTran Airways "has been forced to cancel 38 flights around the country and dozens more have been delayed," spokesman Christopher White told AFP.

Flights were still taking off and landing however, because the outage did not affect radar or radio systems, White noted.

"The ripple effect -- regardless of when this system gets back online -- will be felt throughout the day," he said, urging passengers to check the status of their flights online first before heading to the airport.

Poor weather conditions

The problems were further compounded by poor weather conditions in much of the northeastern United States.

"Due to lingering effects from the FAA computer issue earlier today, airlines at both O'Hare and Midway International Airports are still reporting flight delays," the Chicago Department of Aviation said in a statement.

NONE Delays were reported of between 20 to 30 minutes at the two airports, with a few cancellations. Flights to and from the East Coast were held up for 90 minutes.

Hartsfield-Jackson airport said it was continuing to monitor the situation even after the computer problem was resolved.

At Newark International Airport outside New York City, the FAA noted that traffic was experiencing delays of at least one hour and 30 minutes.

Washington area airports were posting delays of up to one hour and 15 minutes.

The East Coast was the most affected because morning traffic had already begun there, but White said he anticipated the Midwest and West Coast to be hit later in the day.

A malfunction in the same computer filing system -- the National Airspace Data Interchange Network -- in August 2008 delayed hundreds of flights in the eastern part of the country, causing the FAA to shift processing to its backup location in Salt Lake City, Utah.