The New York Times is covering the Federal Aviation Administration's rare nationwide ground stop, only the third in decades, issued Friday in what appeared to be a major air traffic control outage that left thousands of flights delayed and passengers stranded at airports like O'Hare and Asheville days before Thanksgiving. Homeland Security Secretary Markwayne Mullin called it a telecommunication outage and said there was no indication of foul play, while it remained unclear whether the A.I. tool the F.A.A. had just begun rolling out nationwide was part of the problem.