Helicopters should not be allowed to travel over a four-mile stretch over the Potomac River following the deadly air collision near Washington in January, according to urgent safety

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

The NTSB said that the long-established route followed by helicopters, referred to in the report as Route 4, is fraught with danger. "Existing separation distances between helicopter traffic operating on Route 4 and aircraft landing on runway 33 are insufficient and pose an intolerable risk to aviation safety by increasing the chances of a midair collision,