The National Transportation Safety Board on Tuesday delivered a sweeping indictment of how the Federal Aviation Administration failed for years to address known safety risks in the airspace around Reagan National Airport, setting the stage for last year’s deadly midair collision.

The collision between a U.S. Army Black Hawk helicopter and a regional American Airlines jet killed all 67 people aboard both aircraft when they struck over the Potomac River just southeast of Ronald Reagan Washington National Airport. It was the deadliest U.S. aviation disaster since 2001.