The U.S. Department of Transportation, which oversees the FAA, says it continues to hire and onboard air-traffic controllers and safety professionals, including mechanics and other support staff. The agency declined to detail the full number of firings, the positions of those employees and where those staffers are based.

A union representing air safety personnel said it’s reviewing the fallout from a slew of firings late Friday that affected US Federal Aviation Administration employees, just a few weeks after the worst US civil aviation disaster in decades.