Flight departures began resuming early Wednesday across the United States after an overnight outage to a key air-traffic system prompted authorities to ground all planes nationwide.
The Federal Aviation Administration (FAA) said normal air traffic operations were gradually returning as it lifted the ground stop shortly before 9am Eastern time (9pm Thailand time). The disruption stemmed from problems with the Notice to Air Missions system, or Notam (also known as Notice to Airmen in some countries), which conveys advisory information essential for flight operations.
The dramatic disruption was one of the most significant in recent decades for the FAA and came after a year of tests of the US air system as the return from Covid-19 placed extra stress on airlines and air-traffic operations.
Carriers including United Airlines and Southwest Airlines said travellers should expect schedule changes, including delays and cancellations, even as flight operations began resuming. The flight-tracking website FlightAware showed 4,314 delays for US flights at 9.22am New York time.
The grounding ultimately could affect more than 2 million passengers booked on 19,621 domestic flights, according to the aviation data provider Cirium. That doesn’t include travellers on 1,843 international flights scheduled to arrive in the US on Wednesday.
The computer system that shares the notices to pilots, airlines and other users began developing problems late Tuesday night and had to be completely taken down in the early hours of Wednesday, said a person familiar with the situation who asked not to be identified. FAA technical workers have been troubleshooting the system since then, the person said.
There was no indication that the outage affected the agency’s ability to track and guide aircraft, or that it caused any safety incidents.
President Joe Biden was briefed on the situation by Secretary of Transportation Pete Buttigieg, the White House said. The president ordered a full investigation, but there is “no evidence of a cyberattack at this point”, it said.
The biggest European airlines said they were largely unaffected by the disruptions, with flights from British Airways, Air France and Deutsche Lufthansa operating normally even as domestic US flights were halted, the carriers said.
Given the early hour of the disruption in the US, international flights were either still on the ground or nowhere near US airspace, giving pilots more turnaround time to react.
