WASHINGTON >> Thirteen of the nation’s busiest air traffic control facilities are suffering from a shortage of air traffic controllers, a problem that demands “urgent attention,” a government watchdog told lawmakers last week.

The number of fully qualified controllers is “below the minimum staffing requirements” the Federal Aviation Administration has set, Matthew Hampton, a Department of Transportation assistant inspector general, told members of the House transportation aviation subcommittee. He didn’t provide a list of all 13, but cited facilities in New York, Dallas, Denver and Chicago as examples.

The facilities also are under stress because a large share of their controllers are still being trained and not yet competent to work on their own, he said. Many of their experienced controllers also are eligible to retire. The FAA’s mandatory retirement age for controllers is 56.

He cited several reasons control towers are understaffed: a lack of precision in the FAA models for estimating staff requirements; failure to fully use systems to determine the best controller schedules; lack of accurate and complete data on planned retirements; and poor communication between FAA headquarters and field offices.