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Flights have resumed across the United States after a computer outage at the Federal Aviation Administration (FAA) resulted in a flight halt.
At 9am ET on Wednesday (1am Thursday AEDT) the FAA lifted the ground stop, which had resulted in thousands of delays quickly cascading through the system at airports nationwide.
"Normal air traffic operations are resuming gradually across the US following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews," the FAA said in a statement on Twitter.
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Delays and cancellations accelerated rapidly through the morning after flights were grounded around 7.20am ET (11.20pm AEDT).
Over 4000 flights were stuck on the ground around 8.50am ET (12.50am Thursday AEDT), which is more than all the delayed flights for the entirety of the previous day, according to the flight tracking website FlightAware.
More than 696 had been cancelled earlier in the day. Those numbers are likely to grow, as the groundings impacted almost all aircraft, including cargo and passenger flights.
However, some medical flights were given clearance and the outage did not impact military operations.
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Due to heavy congestion, the FAA cleared flights to depart at Newark Liberty and Atlanta Hartsfield-Jackson airports. The agency said that normal air traffic operations were resuming gradually across the US following the outage.
More than 21,000 flights were scheduled to take off in the US across Wednesday – most of these domestic trips along with about 1,840 international flights were expected to fly to the US, according to aviation data firm Cirium.
Airlines for America, an association representing US airlines, earlier said the outage was "causing significant operational delays."
Major US carriers including United Airlines, Delta and American Airlines all said had grounded flights in response to the situation.
Passengers were first told of the FAA outage around 6.30am (10.30pm AEDT), with the agency providing updates approximately every half hour.
The NOTAMS system that is experiencing the outage provides "critical flight safety operation information," the airline says.
The FAA stipulates NOTAMS are not to be relied on as a sole source of information, and so some flights may be able to satisfy safety requirements by using other data.
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While the White House initially said that there is no evidence of a cyberattack, President Joe Biden said "we don't know" and told reporters he's directed the Department of Transportation to investigate the cause of the disruption.
The US President addressed the FAA issue before leaving the White House on Wednesday morning to accompany his wife to a medical procedure at Walter Reed National Military Medical Center outside of Washington.
He said he had just been briefed by Transportation Secretary Pete Buttigieg, who told him they still had not identified what went wrong.
"I just spoke to Buttigieg. They don't know what the cause is. But I was on the phone with him about 10 minutes," Biden said.
"I told him to report directly to me when they find out. Air traffic can still land safely, just not take off right now. We don't know what the cause of it is."
Buttigieg said in a tweet that he is in touch with the FAA and monitoring the situation.
The FBI did not immediately respond to a request seeking comment.
International flights bound for the US not impacted
The last flight out of Sydney International Airport to the US was a Hawaiian Airlines flight, which took off at 9.26pm.
While the Brisbane Qantas flight to Los Angeles appears to be taking off as scheduled.
European flights into the US appeared to be largely unaffected, with planes continuing to take off from Amsterdam and Paris despite the situation.
A Schiphol Airport spokesperson told CNN that "a workaround had been issued" and flights were still departing from Amsterdam.
No flights have been cancelled from Paris' Charles de Gaulle airport, but delays were expected, according to the airport's press office. Frankfurt Airport also told CNN it had not been impacted.
A London Heathrow Airport spokesperson told CNN that they were "not aware of cancelled flights and that flights to the US had left recently."
Irish carrier Aer Lingus said services to the US continue and Dublin Airport's website showed that its flights to Newark, Boston, Chicago and Los Angeles were running on schedule.
"Aer Lingus plan to operate all transatlantic flights as scheduled today," the carrier said in a prepared statement.
"We will continue to monitor but we do not anticipate any disruption to our services arising from the technical issue in the United States."
Inbound international flights into Miami International Airport continued to land, but all departures have been delayed since 6.30am (10.30pm AEDT), said airport spokesman Greg Chin.
Source: 9News
