The Federal Aviation Administration grounded all flights nationwide Friday afternoon due to communications problems at regional air traffic control centers, an FAA notice said. The ground stop was being imposed “due to extraordinary circumstances and for reasons of safety,” according to the notice. Transportation Secretary Sean Duffy said a communications issue was affecting the regional air traffic control centers that direct planes between airports nationwide. He said FAA technicians are investigating. This is the first nationwide ground stop since January 2023 when a key FAA computer system malfunctioned. Before that the last time had been after the Sept. 11, 2001, attacks.