The National Transportation Safety Board on Tuesday called for immediate changes at Ronald Reagan Washington National Airport, saying the current helicopter routes around the busy airport "pose an intolerable risk to aviation safety.

Helicopters should be barred from a four-mile stretch over the Potomac River when flights are landing on Reagan National Airport’s Runway 33, National Transportation Safety Board Chair Jennifer Homendy said as the NTSB unveiled “urgent safety recommendations” after the deadly mid-air collision in January.

The National Transportation Safety Board has released their preliminary report into the deadly midair collision between an American Airlines flight and a U.S. Army Black Hawk helicopter over Washington,