The FAA is permanently closing one key route and evaluating alternative helicopter routes after the National Transportation Safety Board this week made two urgent safety recommendations following the Jan. 29 mid-air collision of an American Airlines regional jet and an Army helicopter that killed 67 people.

The US Federal Aviation Administration detailed a series of restrictions on helicopter traffic near Ronald Reagan Washington National Airport following a deadly midair collision in January.

The closure comes after crash investigators said there was a history of safety risks near the busy airport that had gone unaddressed.