The crash of an American Airlines passenger jet and a U.S. Army Black Hawk helicopter near Reagan Washington National Airport on Wednesday highlighted issues around the congested airspace shared by civilian and military aircraft over the U.

United States President Donald Trump has described the midair collision between a US Army helicopter and American Airlines passenger plane as a “bad situation that should have been prevented.” Trump impliedly blamed the control tower questioning why it didn’t tell the helicopter what to do instead of asking if they saw the plane.

A Sikorsky UH-60 Black Hawk helicopter of the US Army was involved in the mid-air collision with an American Airlines plane