CHICAGO (AP) -- A software glitch in an FAA flight-plan computer south of Atlanta this week has illustrated how easily a single, seemingly isolated snafu can trigger disarray across in the country's aging air-traffic system.

The FAA says the problem yesterday delayed around 650 flights in the East and Midwest, including Chicago.

The chief operations officer for the U.S. air traffic system, Hank Krakowski (krah--KOW'-skee), says the computer's now operating normally. But he says yesterday's disruptions were frustrating.

He says it shows that just upgrading the network piecemeal isn't good enough. He says what's needed is whole-scale modernization.

The air traffic controllers union says it also supports modernization. But it accuses the FAA of being too fixated on future technology and of not maintaining existing equipment well enough.

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