In images shared by the NTSB, the crumpled metal that was once a working military helicopter can be seen being lifted from the water by a crane floating atop a barge in the Potomac River.

Data from a cockpit voice recorder of the Black Hawk helicopter that collided with an airliner near Washington, D.C, last week suggests the crew was wearing night-vision goggles.

A key safety system was turned off in a US army helicopter when it crashed into an American Airlines flight last week, killing 67 people.