Accident investigators have recovered black boxes from both the American Airlines jet and the military helicopter involved in Wednesd

Investigators have recovered the flight recorders—also known as black boxes—from both the commercial jet and the military helicopter involved in the mid-air collision near Reagan National Airport in Washington,

It's one of the most important pieces of forensic evidence following a plane crash: The so-called “black box." There are actually two of these remarkably sturdy devices: the cockpit voice recorder and the flight data recorder.