The pilots of a U.S. Army helicopter that collided with a passenger jet over Washington in January would've had difficulty spotting the plane while wearing night vision goggles, experts told the National Transportation Safety Board on Friday.

Experts testified in front of the National Transportation Safety Board on Friday about what may have led to the deadly midair collision in Washington, D.C. that killed 67 people. They said that night-vision goggles worn by the Black Hawk helicopter pilots may have hindered their ability to see the colored lights on the American Airlines jet.