Recent maintenance by contractor L3Harris on the FAA's legacy telecommunications infrastructure triggered the November 13 nationwide ground stop. During a routine copper-to-fiber-optic upgrade at a remote site, a router began flooding the network with excessive connection attempts, overloading switches and routers in the FAA Telecommunications Infrastructure network and causing intermittent radar and voice communications failures across 17 of 22 air route traffic control centers. Officials ruled out cyberattacks or AI involvement while investigating whether the incident stemmed from installation error or faulty equipment. The event exposed ongoing vulnerabilities in decades-old systems, prompting renewed calls for modernization funding and a formal root-cause analysis expected in coming weeks that could clarify liability.