At 8:30 a.m. Saturday, as air traffic controllers watched the skies above Salt Lake City International Airport, a Texas-bound flight morphed into a flight from Nebraska.

Continental Airlines Flight 440 had just left the Salt Lake City International Airport airspace. An air traffic controller transferred the flight to the computer of another air traffic controller. But the computer misidentified it as SkyWest Flight 4881, which had just landed in Salt Lake City from Omaha, Neb.

The air traffic controller reported the glitch to management and the Federal Aviation Administration. The glitch occurred on a new air traffic control computer system under testing in a facility on 700 North, scheduled to go live nationally next year. Management shut down the new system, fired up the backup system and then replaced the backup with the 20-year-old system air traffic controllers are currently using.

To buy time to shut down and fire up the computer systems, air traffic control required pilots space their planes farther apart. As a result, 23 flights were late Saturday.

The union representing some 220 people who work at the 700 North facility, which monitors 4,500 to 6,000 planes a day at high elevations throughout the western United States, said the Saturday glitch is an example of why they are concerned about traffic safety with the new computer system.

The air traffic controller who recognized the glitch was only watching two planes at the time. But the skies are usually busier.

"It's not uncommon for us to have 15 to 20 aircraft we're in contact with at one time," said Doug Pincock, the 700 North facility's representative of the National Air Traffic Controllers Association.

An FAA spokeswoman, however, said the computer system was supposed to be tested during a light traffic time so that air traffic controllers and management could deal with any hiccups.

"We've identified the problem," said spokeswoman Laura Brown. "There was a data block that identified one aircraft and the system swapped that from one aircraft target to a different aircraft target. We were able to manually switch it back to the correct aircraft. They were able to turn the system down."

Computer programmers are now in the process of developing a software fix, Brown said.