Air travel across the U.S. has continued to experience severe delays as a “surge” of unpaid air traffic controllers have been calling out of work. The Federal Aviation Administration warned Friday that nearly 13,000 air traffic controllers have been working without pay for weeks. “As we head into this weekend, a surge in callouts is straining staffing levels at multiple facilities, leading to widespread impacts across the [National Airspace System],” the FAA said in a post on X. As of Friday,