Authorities are investigating a midair collision between an American Airlines regional jet and a Black Hawk helicopter over the Potomac River near Reagan National Airport in Washington, D.C. Follow along for live updates,

The flight data recorder and cockpit voice recorder, known as the black boxes, may offer clues about what went wrong before the crash.

What is a black box, what can it tell us, and have the data recorders been found from Flight 5342 and the Army's Blackhawk?

The helicopter involved in the fatal midair collision on Wednesday night may have flown off its approved path, The New York Times reports.