A massive winter storm known as Fern forced airlines to cancel more than 10,000 U.S. flights Sunday and effectively shut down operations at some of the nation’s busiest airports across the Northeast and Mid-Atlantic. The National Airspace System Status listed 30 airports that were closed as of Sunday afternoon, with disruptions expected to extend into Monday, according to FlightAware data and airline advisories. By mid-day Sunday, cancellations reached historic levels since the pandemic-era and