The United States has lifted its order to ground departing flights nationwide as a major communications outage continues to disrupt air travel.
asserted
outage → lift → travel
The Federal Aviation Administration (FAA) cited "extraordinary circumstances and reasons of safety", with the White House blaming outdated air traffic control technology for the outage.
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House → cite → outage
Thousands of flights into and out of the US were delayed or cancelled, leaving airlines and passengers scrambling to work out their next steps.
The ABC understands the US "ground stop" has caused some delays to a small number of US-bound flights from Australia.
Here's what we know about the unfolding situation so far.
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we → delay → situation
What caused the problem?
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What → cause → problem
US Homeland Security Secretary Markwayne Mullin has attributed the disruption to a telecommunications issue.
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Mullin → attribute → issue
"It's just a telecommunications outage as of right now," Mr Mullin told reporters at the White House earlier on Friday, local time.
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Mullin → tell → Friday
There's no reason to be concerned about your loved ones if they're flying."
It is not yet confirmed what specifically caused the communications failure.
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what → be → failure
Mr Mullin had earlier said investigators would examine whether there was any connection to the FAA's nationwide rollout of a new artificial intelligence (AI) system designed to help identify problems and reroute aircraft.
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investigators → say → aircraft
However, the system operates from a single location near Washington DC and provides recommendations to air traffic control centres.
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system → operate → centres
US President Donald Trump has also rejected suggestions the new AI technology was responsible for the disruption.
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technology → reject → disruption
In his latest press conference, US Transportation Secretary Sean Duffy blamed "old technology" for the outage.
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Duffy → blame → outage
"What we have is an incredibly old air traffic control system," he said.
"
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he → say → What
We have analogue telecoms, our routers actually got overloaded with data … and they started to give us inconsistencies in the data … because of that we shut the system down," he says.
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he → have → system
"It is the old hardware that went down."
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that → go → ?
Speaking to ABC News, Shawn Pruchnik, an associate professor in Ohio State University's aviation department, said officials made the right call by grounding departing aircraft as a precaution.
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officials → speak → precaution
"We have this significant problem of airplanes at higher altitudes that cannot communicate with air traffic control, so the solution to that is less airplanes up there," he said.
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he → have → that
"Keep everyone down, let everyone land."
Was it caused by a threat to the US?
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it → keep → US
Mr Mullin said there was currently no indication the outage was the result of a nefarious attack.
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outage → say → attack
However, he later added:
"We're not ruling out anything at this point.
"
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We → add → point
The first thing is [to make sure] everybody that is flying in is safe."
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that → make → ?
In a subsequent press conference, Mr Mullin reiterated that there were no signs pointing to a cyber attack for now.
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Mullin → reiterate → attack
"Typically, somebody's going to raise their hand up and say, 'Hey, we did that'.
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we → go → that
We haven't seen any footprints … of people that have got into the system," he said.
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he → see → system
"It appears this was mechanically driven.
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this → appear → ?
However, we are still looking.
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we → look → ?
"
Is it linked to the Microsoft outage?
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it → link → outage
Microsoft has denied any known connection between its recent global outage and the FAA's nationwide stoppage.
"We have no indication that the FAA's nationwide ground stop is related to any Microsoft services," the company said on X.
The statement came amid speculation about a possible link to Microsoft's 21-hour global outage, which was resolved earlier on Friday.
Mr Mullin also dismissed the suggestion of a connection, telling reporters: "I don't see any reason to connect those two at all."
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I → deny → two
Which flights were affected?
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flights → affect → ?
The FAA's order applied to departing flights across the US, grounding nearly all aircraft scheduled to take off during the five hours it was in effect.
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it → apply → effect
The agency also asked Eurocontrol, its European counterpart, to suspend flights to the US from its 42 member states, including Türkiye, Morocco and Israel.
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agency → ask → Türkiye
Aircraft that were already in the air when the order was issued were allowed to continue safely to their destinations.
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order → issue → destinations
The full scale of the disruption is still emerging, but the impact has already been felt by tens of thousands of travellers.
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impact → emerge → travellers
Flight-tracking website FlightAware reported about 9,814 delays on flights into and out of the US, alongside more than 4,749 cancellations.
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website → track → cancellations
Those figures are continuing to change as the disruption unfolds.
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disruption → continue → ?
Meanwhile, the full scale of the impact on Australian flights remains unclear.
uncertain
scale → remain → flights
Before the US order was lifted, a Sydney Airports spokesperson had said all US-bound flights from Sydney had been grounded.
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flights → lift → Sydney
Since the order was lifted, the spokesperson said:
"Flights scheduled to depart Sydney for the United States are expected to depart as planned.
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Flights → lift → States
Passengers should continue to check with their airline for the latest information."
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Passengers → continue → information
The ABC is continuing to stay in touch with Sydney Airport for further updates.
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ABC → continue → updates
Can planes already in the air land safely?
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planes → land → air
…and 18 more, not listed.
The Aporia
