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.

Both crashed into the Potomac River, with no survivors among the passengers, pilots, or crew.NTSB’s Urgent Safety ActionFollowing its preliminary investigation, the NTSB determined that the existing separation distances between aircraft using helicopter Route 4 and runway 33 traffic at DCA are insufficient and increase the risk of midair collisions.

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,

More than a month after an American Airlines plane and a Black Hawk helicopter collided near Reagan National Airport (DCA), killing 67 people, officials with the National Transportation Safety Board (NTSB) are calling for immediate changes to helicopter routes around DCA because they said it poses “an intolerable risk to aviation safety.