The US Federal Aviation Administration (FAA) lifted a nationwide ground stop on Friday after a communications failure at air traffic control centres disrupted flights across the country, triggering the longest nationwide aviation shutdown since the September 11, 2001 attacks.
Transportation Secretary Sean Duffy said US airspace reopened at 8:15pm Eastern Time (6:15am Pakistan time on Saturday). However, he warned that departures would resume gradually and airlines would need time to restore normal operations.
“It’s going to be slow,” Duffy told reporters at the White House.
By 11:30pm, nearly 10,000 flights had been cancelled, according to flight-tracking website Flightradar24. Delta Air Lines and American Airlines each reported more than 2,200 cancellations, while United Airlines recorded around 1,800.
Some aircraft at major airports had reportedly waited more than five hours for gates, while tens of thousands of passengers remained stranded nationwide.
Communications Failure Disrupts Air Traffic Control
Duffy said the problem began at 3:36pm when air traffic control centres experienced instability in radar and communications systems.
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He explained that overloaded switches and routers produced inconsistent data, prompting authorities to shut down the system as a precaution.
Duffy said the FAA had not completely lost radar or communications capabilities and had continued landing thousands of aircraft safely.
He confirmed that the immediate technical problem had been fixed and flying was safe, but warned that the wider air traffic control system required modernisation to prevent similar incidents.
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Duffy criticised Congress for not providing sufficient funding to replace ageing air traffic control technology and called for $50 billion to modernise the system.
Earlier on Friday, the White House and Department of Transportation had urged lawmakers to approve $30.1 billion for improvements to airports and air traffic control infrastructure.
Homeland Security Secretary Markwayne Mullin said investigators had found no evidence so far that the outage resulted from a cyberattack or a rogue artificial intelligence system.
He said the failure appeared to be mechanically driven, although investigators had not ruled out other possibilities.
The National Security Agency was working with the Department of Homeland Security on the investigation.
Two airline officials said the disruption appeared to involve a telecommunications network overseen by L3Harris Technologies. The network supports critical radio frequencies used by air traffic controllers to communicate with pilots. The company did not immediately respond to a request for comment.
Passengers Face Days of Travel Disruption
Although the FAA lifted the ground stop, delays and cancellations continued at airports from Boston and New York to Los Angeles and Seattle.
Passengers crowded departure halls and airline service counters as airlines worked to reschedule flights and reposition aircraft and crews.
American Airlines said it was prioritising international flights and services to smaller cities outside its major hubs to support a faster recovery.
Airlines will not be required to compensate passengers for the disruption because the cancellations resulted from an FAA system failure rather than carrier-controlled operations.
The only other nationwide ground stop since the September 11 attacks occurred in January 2023, when the FAA halted domestic departures for approximately 90 minutes following a separate system outage.
Airline Shares Decline
The disruption also affected airline stocks. Shares of American Airlines, United Airlines and Delta Air Lines fell between 1% and 2% in after-hours trading, while JetBlue Airways declined by around 3%.
Aviation analysts warned that the four-hour nationwide grounding could continue affecting airline schedules for several days as carriers work to restore normal operations.
