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).

A preliminary report by the Federal Aviation Administration found that staffing at the Ronald Reagan Airport air traffic control tower was “not normal” at the time of the deadly collision between an Army Black Hawk helicopter and an American Airlines regional jet.