An American Airlines regional jet went down in the Potomac River near Washington, D.C.'s Ronald Reagan Washington National Airport after colliding with a U.S. Army Black Hawk helicopter on Wednesday night, with no survivors. Sixty-four people were on board the plane, which departed from Wichita, Kansas. Three soldiers were on the helicopter.

An airspace cluttered with passenger planes and military aircraft. A history of near-crashes. And a growing shortage of air traffic controllers available to manage it all. Some experts, politicians and airport managers have been warning for years of the risks posed by the crowded airspace and volume of flights at Ronald Reagan Washington National Airport (DCA).