Firings affected several hundred workers responsible for maintaining FAA radar, landing systems and navigational aids.

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.

Emails to air-traffic controllers, according to a second air-safety union president, came “from an ‘exec order’ Microsoft email address” — not a government email address.