WASHINGTON » Utah's two U.S. senators are urging the Federal Aviation Administration to hold off testing a new computer system at a Salt Lake City air traffic control center that guides planes across portions of eight states.

Republican Sens. Bob Bennett and Orrin Hatch wrote FAA Administrator Randy Babbitt on June 11, asking him to delay a test of the new system at the Salt Lake Air Route Traffic Control Center, one of the FAA's 20 en route centers around the country.

Air traffic controllers said there are glitches in the system's software, including one that could cause controllers to frequently lose important information about the planes they are controlling.

The senators called that "simply unacceptable."

"Safety concerns demand that ERAM (the computer system) not be implemented until it meets and exceeds the standards of reliability and stability of the system it replaces," the senators wrote.

FAA spokeswoman Laura Brown said the agency has a meeting scheduled for Tuesday with the union representing air traffic controllers to discuss the test. She said agency officials still have confidence the test can take place as planned.

The test is scheduled from midnight to 4 a.m. on June 18, said Doug Pincock, an air traffic controller in Salt Lake City. During that period the main computer system that the control center has used for nearly two decades will be switched off and the new

system, known as En route Automation Modernization, will be switched on, Pincock said.

The test was originally scheduled for June 13, but was moved back to June 18. Two Utah House members -- Democrat Jim Matheson and Republican Jason Chaffetz -- also wrote Babbitt in early June before the rescheduling seeking a delay in the test.

"These appear to be serious concerns," Matheson said in his letter.

FAA officials are aware that the ERAM continues to have software problems, said Pincock, a representative for the National Air Traffic Controllers Association. The agency has refused so far to reschedule the test even though the contractor, Lockheed Martin, has promised to have software fixes available by June 25, he said.

The facility handles about 4,500 flights a day over Utah, Montana, South Dakota, North Dakota, Idaho, Washington, Oregon and Nevada, Pincock said.

Salt Lake is the first control center to receive an ERAM. Eventually all 20 centers will shift to ERAMs from the computer systems they have been using, known as "the Host," Pincock said.

The new computer systems are critical to FAA's top priority, which is implementing its Next Generation Air Transportation System, known as NextGen. The program will replace the current radar-based air traffic control system, which relies on World War II-era technology, with a satellite-based system to track planes.

The ERAM systems are needed because the Host systems won't be able to handle the all demands of NextGen, Pincock said.

"We welcome the update to the technology and the enhancements it's going to provide, we just want it to be complete and ready before they deploy it," Pincock said. "We think it's foolhardy for them to proceed with a system with known flaws just for the sake of proceeding."