Sending so many screeners to training leaves checkpoints understaffed, the directors said. Instead of three hours a week, their screeners get about three hours of training a month.

That's despite the fact screeners get hurt or sick more than any other federal employees, suffering back, shoulder and knee injuries, pulled muscles, tendonitis, and cuts and puncture wounds from sharp objects tucked in luggage.

In the fiscal year ending last September, nearly one in five Transportation Security Administration (TSA) employees sought workers' compensation, according to OSHA.

Overall, 4.2 percent of federal workers suffered work-related injuries or illness. TSA's percentage was 19.4 — nearly five times as high, topping Park Service employees and federal marshals.