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 seeking more flight restrictions on helicopters around Ronald Reagan Washington National Airport. The NTSB's "urgent" recommendations come more than a month after a Jan.

The National Transportation Safety Board said the separation between helicopters and jets in the area was insufficient and increased “chances of a midair collision.”