Continued staffing shortages in air traffic control facilities around the country were again causing delays at airports on Friday as the government shutdown neared the one-month mark. U.S. Transportation Secretary Sean Duffy has been warning that travelers would start to see more flights delayed or canceled as the nation's controllers continue to work without pay during the shutdown, which began Oct. 1. “Every day there's going to be more challenges,” Duffy told reporters Thursday outside the White House after a closed-door meeting with Vice President JD Vance and aviation industry leaders to talk about the shutdown’s impact on U.S. travel.