The U.S. commercial aviation system will not have enough air traffic controllers to safely manage the growing number of daily flights unless the government steps up its hiring and training program, two government investigators told a House panel yesterday.

Half of the air traffic controller workforce is projected to retire and 93 percent of controller supervisors will be eligible to retire by 2012, the General Accounting Office and Department of Transportation's Inspector General said yesterday. The Federal Aviation Administration has hired one controller this year and has not requested funds in fiscal 2005 to hire any new controllers.

Both government watchdogs criticized the FAA's poor planning for the expected staffing shortage, pointing out that it takes an average of three years to train a new controller, according to the GAO.

"The urgency for focusing on the problem is here," said JayEtta Z. Hecker, director of the GAO's physical infrastructure team. "Hiring and training decisions have to be made with a longer-term perspective."

The FAA hired 762 new controllers in 2003 and 400 retired last year.

FAA Administrator Marion C. Blakey defended her agency yesterday, saying it is actually overstaffed by 87 controllers, according to the agency's staffing model, but she acknowledged that 10 locations are short-staffed, including some centers that handle large volumes of the nation's air traffic.

"We are addressing your concerns," Blakey told the House Transportation and Infrastructure aviation subcommittee. She said the agency is developing a report to Congress due in December that will reevaluate staffing models and training methods. The FAA is also considering pushing back the mandatory retirement age for controllers and shifting more of its training to private schools, which would decrease the agency's training costs.

More than 20 years ago, then-President Ronald Reagan fired the nation's 12,000 air traffic controllers in a labor dispute. Most of the controllers hired after that incident are now reaching mandatory retirement age, set by the FAA at age 56.

The union representing air traffic controllers opposes an extension of the mandatory retirement age. Ruth E. Marlin, executive vice president of the National Air Traffic Controllers Association, said that the FAA needs to begin hiring new controllers rather than conduct another study.