FAA Nationwide Ground Stop Grounds Nearly 11000 Flights After ATC Communications Collapse

The Federal Aviation Administration issued a nationwide ground stop Friday afternoon, halting all departing flights across the United States after a telecommunications failure knocked out communications at every Air Route Traffic Control Center. Transportation Secretary Sean Duffy said FAA technicians were investigating the outage, which the agency described as arising from "extraordinary circumstances and for reasons of safety." By late Friday, nearly 11,000 flights had been delayed or cancelled, up from roughly 7,000 two hours earlier, with major hubs including Newark, Houston, O'Hare, Atlanta, JFK and Teterboro reporting multi-hour delays.

The disruption spread internationally. Canada imposed ground stops at Toronto and Montreal before lifting them, and Eurocontrol halted all departures from its member states bound for US airports at the FAA's request. United Airlines said no new domestic departures would occur while the stop remained in effect, and Alaska Air cancelled and diverted flights. Airline officials warned that some US carriers might cease operations for the rest of Friday if service did not resume.

DHS Secretary Markwayne Mullin told reporters in an emergency briefing that there was no indication of a nefarious attack and that the situation was "not another 9/11," though he said he could not rule out AI or a cyberattack as contributing factors. The FBI investigated and said the failure was not the result of a cyberattack or crime. According to CBS News and a subsequent report citing L3Harris, a network update by defense contractor L3Harris, which is replacing decades-old copper connections with high-speed networks across all FAA facilities, crashed the private communications system underpinning air traffic control.

Investigators also focused on the FAA's new $875 million AI air traffic management system, known as SMART, which the agency rolled out to all 22 en route control centers on November 10, just three days before the ground stop. House Democrats had already written to the FAA last month warning that the system could interfere with experienced controllers' decisions or hallucinate safety-critical information, and air traffic controllers said they had received limited training and had no role in designing or testing it. DHS confirmed it was examining the SMART rollout as a potential cause. The National Weather Service separately reported nationwide internet and communications disruptions during the same window, though Microsoft said its own concurrent global outage affecting Outlook and Teams appeared unrelated to the FAA failure.

The FAA ground stop is only the second nationwide halt in modern history outside the September 11 attacks, following a NOTAM system failure in January 2023. President Trump was briefed on the situation, and Mullin said federal agencies were coordinating a response.