Roll Call:  “An army of small drones are heading for the national airspace this holiday season . . . . The flood of new aircraft — and new pilots — is expected as federal officials are preparing to tighten their grip on drone fliers. The Federal Aviation Administration said in October it would require registration of drones . . . . Federal rules already require commercial users to register to fly drones, also known as unmanned aircraft systems. But officials, as well as representatives of the aviation industry, are worried that recreational drone users, including the pajama-clad pilots who might take their drone for a virgin flight on Christmas Day, might not understand the rules behind launching into U.S. airspace.”