WASHINGTON, Jan 11 (Reuters) – U.S. flights are slowly starting to resume and cancel ground stops after the Federal Aviation Administration (FAA) urgently fixed a system glitch that grounded all U.S. outbound flights overnight .
“Normal air traffic operations are gradually resuming across the U.S. after an overnight outage in the air task notification system that provides safety information to crews. The ground stop has been lifted. We continue to investigate the cause of the initial issue,” the FAA tweeted Say.
The FAA earlier ordered airlines to suspend all domestic flights after its pilot alert system collapsed.
The FAA said that shortly before 8:30 a.m., Newark and Atlanta airports resumed departures “due to air traffic congestion in those areas. We expect other airports to resume departures by 9 a.m. ET.”
The FAA is expected to implement a ground delay program to address a backlog of flights grounded for hours. Flights already in the air were allowed to continue to their destinations.
U.S. President Joe Biden ordered the Department of Transportation to investigate the outage and said it was not yet clear what caused the outage. Asked whether a cyberattack was behind the outage, Biden told reporters at the White House, “We don’t know.”
The FAA said it was working to restore a system that alerted pilots to hazards and changes to airport facilities and procedures that stopped processing updates.
The FAA tweeted: “The FAA is still working to fully restore the disrupted Notification to Air Tasks (NOTAM) system. While some functionality is beginning to return to normal, NAS operations remain limited.”
Flight-tracking website FlightAware showed 3,704 U.S. flights were delayed as of 8:39 a.m. ET.Another 656 people had been canceled as of 8.39am
Shares of American Airlines fell in premarket trading on Wednesday. Southwest Airlines fell 2.4 percent, while Delta Air Lines (DAL.N), United Airlines (UAL.O) and American Airlines (AAL.O) fell about 1 percent.
A NOTAM is a notice containing information necessary for those involved in flight operations but not known in sufficient time in advance to be announced by other means.
Information on long-haul international flights can run up to 200 pages and may include items such as runway closures, bird hazard warnings and construction obstacles.
United Airlines (UAL.O) said it has temporarily postponed all domestic flights and will issue an update when it learns more from the FAA.
Both Lufthansa and Air France said they would continue to operate flights to and from the United States, while the French carrier said it was monitoring the situation.
Operators of Paris’s international airports – Paris-Charles de Gaulle and Orly – said delays were expected.
Austin-Bergstrom International Airport tweeted that ground stops across the country were causing delays. A ground stop is an air traffic control measure that slows or stops an aircraft at a specific airport.
In an early advisory on its website, the FAA said its NOTAM system had “failed,” although NOTAMs issued before the outage were still visible. Earlier this month, a problem with another airline’s computer control system delayed dozens of flights in Florida.
A total of 21,464 flights were scheduled to depart from U.S. airports on Wednesday, carrying nearly 2.9 million passengers, Cirium data showed.
American Airlines had the most flights from U.S. airports with 4,819 flights, followed by Delta Air Lines and Southwest Airlines, according to Cirium data.
Reporting by David Shepardson in Washington, Abhijith Ganapavaram in Bengaluru, Jamie Freed in Sydney and Rajesh Kumar Singh in Chicago; Additional reporting by Nathan Gomes and Steve Holland in WashingtonWriting by Shailesh Kuber and Alexander SmithEditing by Edmund Blair and Nick Zieminski
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