The U.S. Department of Transportation may need to close "certain parts of the airspace" if the government shutdown continues into next week, Transportation Secretary Sean Duffy said Tuesday.  "You will see mass flight delays, you'll see mass cancellations," Duffy said at a press conference in Philadelphia. "And you may see us close certain parts of the airspace because we just cannot manage it, because we don't have the air traffic controllers." He added, "We will restrict the airspace when we