A massive telecommunications failure brought air travel across the United States to a near standstill on Friday-Saturday, forcing aviation authorities to suspend departures nationwide in one of the most serious disruptions to the country's aviation network in decades.
The unprecedented disruption left thousands of passengers stranded, affected operations at major airports and raised fresh questions about the reliability of America's ageing air traffic control infrastructure.
According to flight-tracking website FlightAware, at least 10,343 flights within, into or out of the US had been delayed, while 1,479 flights were cancelled, based on figures available during the disruption. The numbers could rise as airlines struggle to restore normal schedules.
The Federal Aviation Administration (FAA) ordered a nationwide ground stop shortly before 4 pm Eastern Time (past midnight in India) after a communications failure affected regional air traffic control centres responsible for managing aircraft movements across American airspace.
The agency described the situation as extraordinary and imposed the restrictions as a precautionary safety measure.
US Transportation Secretary Sean Duffy confirmed that the disruption involved communications systems serving Air Route Traffic Control Centres, which coordinate flights travelling between airports. The FAA operates 22 such regional centres, making them a critical part of the country's aviation infrastructure.
The ground stop prevented aircraft from taking off while allowing controllers to manage planes already airborne. International flights were handled individually, depending on safety conditions and available communications.
FAA technicians began investigating the failure, but authorities had not established its underlying cause.
The scale of the problem was particularly concerning because air traffic control depends on continuous communication between pilots and ground controllers to maintain safe distances between aircraft.
With those communications disrupted, allowing more planes into an already congested airspace would have increased operational risks.
The sudden nationwide shutdown prompted speculation about whether the US aviation system had been targeted by a cyberattack. However, Homeland Security Secretary Markwayne Mullin said there was no evidence suggesting deliberate interference.
“There was no indication as of yet that this was a nefarious attack against us,” Mullin said, describing the incident as a telecommunications outage. Nevertheless, authorities were not ruling out any possible cause while investigations continued.
Mullin also sought to discourage comparisons with the September 11, 2001 terrorist attacks, emphasising that officials had no indication of a security threat.
The immediate priority, he said, was ensuring the safety of aircraft already in the air and restoring normal operations.
The shutdown rapidly affected major aviation hubs, including Chicago, Denver, Los Angeles, Newark, Las Vegas, Orlando, Houston and Phoenix.
At Denver International Airport, passengers were asked to leave aircraft with their belongings, while others queued at airline counters to rearrange their journeys. At Chicago's O'Hare International Airport, aircraft continued landing even as departures remained suspended.
Flight-tracking platform Flightradar24 indicated that more than 1,000 aircraft bound for US airports were already airborne when the nationwide restrictions took effect.
Another aviation tracking service, Flighty, estimated that more than 30,000 departures and arrivals remained scheduled for the rest of Friday when the disruption began.
American Airlines and United Airlines warned passengers to expect substantial disruption. The suspension also created operational difficulties for airlines attempting to reposition aircraft and crews across their networks.
Such nationwide suspensions are exceptionally rare. The first major shutdown occurred following the September 11, 2001 terrorist attacks. The second came in January 2023, when a malfunction in the FAA's system for issuing critical safety notices temporarily halted domestic departures for nearly two hours.
Friday's incident is therefore the third nationwide ground stop in 25 years and the second since 2001 caused by a technical disruption rather than a terrorist attack.
The timing could hardly be worse for airlines. Thanksgiving, one of America's busiest travel periods, is approaching, with industry estimates suggesting approximately 2.7 million passengers could fly daily during the holiday period.
Even after communications are restored, airlines may need considerable time to reposition aircraft, rearrange crew schedules and clear passenger backlogs.
Aviation analyst Robert Mann warned that a prolonged suspension could leave airlines struggling to restore their networks throughout the weekend.
The episode also has implications for international passengers, including travellers from India connecting through major US airports.