The Army goggles would have made it difficult to see the plane's colored lights, which might have helped the Black Hawk determine the plane's direction. The goggles also limited the pilots' peripheral vision as they flew near Ronald Reagan Washington National Airport.

The goggles were among the topics discussed at the NTSB’s third and final day of public testimony over the fatal midair crash near Washington, D.C., which killed 67 people.

Aviation experts said the goggles may have created viewing difficulties for the pilots of a U.S. Army helicopter that collided with a jet in January.