Explained: Families of the 67 who died in last year's midair collision want reforms to prevent the next tragedy

67 people died when an American Airlines jet from Wichita, Kansas, and an Army Black Hawk helicopter collided over Washington, D.C.

NTSB

National Transportation Safety Board, the federal agency investigating the crash and issuing safety recommendations.

FAA

Federal Aviation Administration, the regulator overseeing U.S. air traffic and airspace safety.

ADS-B In

A technology system that lets pilots see the location of nearby aircraft to help avoid collisions.

Black Hawk helicopter

The U.S. Army helicopter involved in the midair collision during a training mission.

lame duck session

The period after November's elections when the current Congress can still pass legislation before new members take office.