Federal investigators looking for the cause of the January collision between a passenger jet and an Army helicopter near Washington, D.C., that killed 67 people are recommending a ban on some helicopter flights.

The National Transportation Safety Board is calling for a ban on some helicopter flights near Reagan Airport after an airliner and Army Black Hawk collided in January.

There's an "intolerable risk to aviation safety" with helicopters and planes flying too close to one another near DCA.