Over 90% of U.S. airport towers are understaffed, data shows

Less than 10% of the nation's airport terminal towers have enough air traffic controllers to meet a set of standards set by a working group that included the Federal Aviation Administration and the controllers' union, according to a CBS News analysis of FAA data.

The issue has received renewed scrutiny following Wednesday night's midair collision between an American Airlines flight and a Black Hawk Army helicopter near Reagan National Airport outside Washington, D.C., that killed 67 people.

Only one air traffic control worker was managing the helicopters and some planes from the Reagan National Airport tower at the time of the collision, a job normally done by two people, two sources told CBS News Thursday.