The National Transportation Safety Board is making a number of recommendations on what they called a "serious safety risk" after the deadly midair collision between a passenger jet and an Army Black Hawk helicopter in Washington D.

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.

Investigators issued their preliminary report Tuesday in the probe into the devastating crash between an American Airlines plane and a U.S. Army Black Hawk helicopter.

The deadly crash took place in January when a military helicopter collided with a passenger jet, killing 67 people.