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.

Hearing that just one air traffic controller was monitoring both planes and helicopters has left many to wonder how common such a situation is. Burke, 81, has filed a petition with the Office of the Pardon Attorney at the U.