Passengers on social media reported flight delays and outages across US. (Representational)
Flights across the United States were affected by a technical glitch with a computer system in an unprecedented disruption on Wednesday. All flights in the US were grounded after a problem in the Notice to Air Missions system (NOTAM), which provides information to flight crews about hazards, changes to airport facilities and other essential information.
The US Federal Aviation Administration (FAA) said normal air traffic operations are resuming gradually across the country. "Normal air traffic operations are resuming gradually across the US," the FAA said on Twitter. "The ground stop has been lifted. We continue to look into the cause of the initial problem."
It had earlier asked airlines to pause all domestic departures until 9 am US Eastern Time and is working to restore a system that alerts pilots to hazards and changes to airport facilities and procedures that had stopped processing updated information.
Flight tracking website FlightAware reported about 5,400 flights within, into or out of the United States had been delayed as of 7 am US Eastern Time. An additional 900 flights were also cancelled.
In an advisory, the civil aviation regulator said its NOTAM (Notice to Air Missions) system had "failed". There was no immediate estimate for when it would be back, the website showed, though NOTAMs issued before the outage were still viewable.
Passengers on social media reported flight delays and outages across the United States, from Hawaii to Washington. Airports from Texas to Pennsylvania confirmed flights were impacted across the country, according to The Washington Post.
Aviation expert Parvez Damania called it a "shocking and unheard-of situation". "I don't recall the last time when the entire airspace of the country was closed. Maybe during 9/11. This is going to cause unbelievable disruption," he told NDTV over the phone.
(With inputs from agencies)