Few answers after glitches halt all flights nationwide for nearly 4.5 hours

Today the US experienced it longest nationwide ground stop since 9/11, with all flights across the country grounded for nearly four and a half hours. The last nationwide ground stop was in January 2023 and lasted 90 minutes after a failure of the crucial Notice to Airmen (NOTAM) system.

Even a brief or partial grounding creates travel chaos that can take days to resolve. Today’s disruption canceled over 7000 flights and left tens of thousands of passengers stranded.

Throughout the day, Transportation Secretary Sean Duffy and Homeland Security Secretary Markwayne Mullin offered various explanations for what caused the problem. When the Federal Aviation Administration first ordered the ground stop just before 4pm ET, they cited a “temporary telecommunications outage”. Duffy later said that radar and air traffic control systems become “overloaded with data” resulting in “instability” in radar data and communications.

Earlier in the day, Mullin (whose department oversees cyber threats) said there was no indication that a cyber attack had taken place. When asked about the possibility of a cyber attack at a later press conference, Mullin answered that “there’s nothing completely certain right now,” before again clarifying that investigators had found no evidence of a cyber breach.

Duffy insists new AI tool not to blame

Both Mullin and Duffy alluded to recently installed “new equipment and technology” interacting badly with older systems. Neither clarified what this “new equipment or technology” was. However, Duffy insisted that the new AI-powered Strategic Management of Airspace, Routes and Trajectories (SMART) system was not responsible. The SMART system was rolled out nationwide for the first time the day before the ground stop.

Duffy blamed Congress (still fully controlled by Republicans) for “kicking the can down the road” and insisted that he needed $50 billion to fully update and upgrade aging flight control systems and infrastructure. Congress has already allocated over $12 billion for the upgrades.

Although there was still little clarity as to what caused the failure, Duffy said that without this addition funding, the air traffic control system “will continue to fail”.