Wednesday night’s fatal crash at Ronald Reagan Washington National Airport involving a commercial airplane and a Black Hawk military helicopter has drawn renewed attention to air traffic controllers and what role they may have played in the accident that is believed to have killed 67 people.

Amid increased concerns about aviation safety, here's how many air traffic controllers there are in the U.S., and how the hiring process works.

A 2023 report determined that over 99% of American airports lacked critical air traffic control staffing. Aggressively recruiting qualified employees was a top priority for transportation officials under President Joe Biden, but policy reversals last week pumped the brakes on hirings.