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).

The Reagan Washington National Airport (DCA) was shut down on Thursday morning after an American Airlines plane and helicopter collided and went into the Potomac River. Several flights were canceled and others were diverted to the Washington Dulles International Airport (IAD).