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).

Before the additional flights were approved, a senator warned that the increase could heighten the risk of collisions.

Congress added more daily flights to the Ronald Reagan Washington National Airport’s schedule last year — and multiple other times over the past quarter century — despite warnings from the airport where 67 people died in a plane crash Wednesday night.