Washington: Air traffic operations are slowly resuming in the US, where a massive technical glitch delayed around 10,000 flights and cancelled 1,300 on Wednesday. Further delays are still expected to continue through at least Thursday and possibly longer, as airlines try to get planes in and out of crowded gates.

Wednesday's disruption was due to a "damaged database file", the BBC quoted the Federal Aviation Administration (FAA) as saying, adding that "at this time, there is no evidence of a cyber attack".

Airports nationwide were affected, from Denver to Atlanta to New York City.

The technical issues marked the first time in nearly two decades that flights across the US were grounded.
No evidence of cyber attack on FAA: White House

There is no evidence of a cyber attack in connection with the technical glitch, the White House said on Wednesday following hours of grounding of flights.

"There is no evidence of a cyber attack at this point. The President has directed the Department of Transportation to conduct a full investigation into the causes and provide regular updates. Again, this is incredibly important, a top priority, the safety of Americans who are flying every day," White House Press Secretary Karine Jean-Pierre told reporters at her daily news conference.

"We want to make sure that they're safe. This is a top priority for the President, top priority for the Department of Transportation and certainly the FAA. And so we want to make sure that we get to the root causes so this does not happen again," she said.

Transportation Secretary Pete Buttigieg, she said, has directed an after action process to determine exactly the root causes and recommended the next steps. "
"The FAA and DOT will continue to be transparent here about the causes of the issue and how we will ensure a system outage of this magnitude does not happen again," Jean-Pierre said.
"Our number one focus is to make sure that the safety of Americans who are flying. We want to make sure that they're safe. And the second part of this is to make sure that this does not happen again. And so, again, there's going to be an after action process and we'll move from there," she said.

The FAA, she said, is working aggressively to get to the bottom of the root causes of what happened with the system outage today and making sure that it doesn't happen again.
"Clearly, the safety of Americans who are flying every day is a number one priority and what they're going to do is to make sure that this doesn't happen again," the press secretary said.