As recovery crews endure cold water and miserable rain Friday to attempt to pull more wreckage of American Airlines Flight 5342 and an Army Black Hawk helicopter from the Potomac River, investigators are intensifying their search for the collision’s cause – with initial concerns already raised about the path of at least one of the aircraft.

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.