Department of Defense Secretary Pete Hegseth has said that the pilots aboard the U.S. Army helicopter that collided with an American Airlines plane were wearing night vision goggles — but an expert says that could have hurt their ability to see other aircraft.

The pilot of the military helicopter that collided into an American Airlines flight was wearing night vision goggles, possibly obscuring their vision, President Donald Trump said Thursday. “On a clear night,

Investigators are looking at the factors that contributed to Wednesday’s tragic plane crash in Washington, D.C., and they may consider whether night-vision goggles played a role. Defense Secretary Pete Hegseth said that a “fairly experienced” crew was conducting an “annual proficiency training flight” in the military helicopter when it collided with the civilian airplane.

Jim Cardoso, the Senior Director for the University of South Florida’s Global and National Security Institute and a U.S. Air Force veteran, discussed the fatal collision between a U.S. Army helicopter and an American Airlines aircraft.