The National Transportation Safety Board on Tuesday recommended that helicopter traffic be banned from a four-mile stretch over the Potomac River when flights are landing at Ronald Reagan National Airport.

The NTSB released a preliminary report on the DCA collision between a plane and helicopter in January while giving urgent recommendations to the FAA.

The release of the reports followed a news conference by NTSB officials who said Federal Aviation Administration procedures that governed the airspace near Reagan National Airport before the crash allowed for an “intolerable risk” that increased the chance of midair collisions,