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The US Federal Aviation Administration has lifted the longest nationwide ground stop of flights since the September 11, 2001 terrorist attacks. The stoppage lasted more than four hours on Friday and was attributed to extraordinary circumstances involving a communication issue that affected all air traffic control centers.
Flight Disruption and International Impact
According to FlightAware, the ground stop resulted in more than 8,500 delayed flights and nearly 8,000 cancellations on Friday. The FAA initially announced at 15:54 EST that all flights departing within the United States would be grounded until further notice. At that moment, more than 3,500 airplanes were in the air, with some being diverted to alternative airports while others continued to their destinations. Hours later, authorities permitted some flights to take off from San Francisco International Airport before reopening the skies entirely at 20:15 EST.
International travel also suffered significant disruptions as Eurocontrol suspended all US-bound air traffic from its member states at the request of the FAA due to technical issues. Eurocontrol encompasses 42 member states, including numerous European Union nations, the UK, Ukraine, Turkey, Israel, and Morocco. Additionally, Sydney Airport grounded all US-bound flights until further notice, and Air Canada cancelled all scheduled services between the US and Canada.
Cause of the Outage and System Overhaul
Transportation Secretary Sean Duffy explained during a news conference on Friday night that a legacy air traffic control communications system became overloaded with data. Duffy stated that analogue telecommunication switches and routers were overwhelmed, causing both communications and radar systems to go down. He emphasized that the aging infrastructure requires a complete overhaul with an estimated price tag of $50 billion, warning that the system will continue to fail without it.
Homeland Security Secretary Markwayne Mullin told reporters that authorities observed zero evidence pointing to a cyber-attack and ruled out any connection to a global Microsoft outage that started on Thursday. Mullin explained that integrating new technology into the outdated air traffic control system ultimately overwhelmed it. Both cabinet secretaries stressed that the traveling public was never in danger during the incident.
Historical Context and Recovery
This event marked only the second nationwide flight stoppage in the United States since the immediate aftermath of the September 11 terrorist attacks. Dr. Guy Gratton, an associate professor of aviation at Cranfield University, told BBC Verify that while the event looked like the worst disruption since 9/11, it was not on that same scale. Dr. Gratton referenced a previous US grounding in 2023 caused by a failure in the Notice to Air Missions system, which lasted one hour and 52 minutes, delayed approximately 9,500 flights, and cancelled about 1,300. Friday’s incident ultimately surpassed that 2023 event in duration.
Addressing the recovery timeline, Sean Duffy noted that the outage would trigger a ripple effect lasting for a few days, explaining that authorities needed time to unwind the disruption. Tens of thousands of travelers remained stranded in airports nationwide, many of them facing uncertainty regarding overnight accommodations. Meanwhile, Delta Air Lines and United Airlines announced they were resuming operations, American Airlines stated it was focusing on operating as many remaining flights as possible, and JetBlue planned to resume its schedule on Saturday morning.
