FAA lifts pause in flight departures caused by computer outage, some delays expected at DIA

An overnight outage at the Federal Aviation Administration delayed thousands of flights on Wednesday morning. More than 400 of those delays were at Denver International Airport.

DIA tweeted to expect some delays and cancellations throughout the day on Wednesday. Passengers are encouraged to check their flight status before heading to the airport. 

The FAA halted all flight departures from the U.S. shortly after 5 a.m., tweeting that it had "ordered airlines to pause all domestic departures until (7 a.m. Mountain Time) to allow the agency to validate the integrity of flight and safety information." The agency subsequently told CBS News the pause, which didn't affect medical or military flights, had been extended to 7:30 a.m.

The FAA lifted the departure ban shortly before 7 a.m. "Normal air traffic operations are resuming gradually," the agency tweeted.

At that time, there were more than 4,000 delays within, into or out of the United States as of 6:50 a.m., according to the flight tracking website FlightAware. 

The agency previously said that that the Notice to Air Missions System (NOTAM) had failed, according to an advisory. "We are performing final validation checks and reloading the system now," the FAA said. "Operations across the National Airspace System are affected."

At about 7 a.m., the FAA said on Twitter that "While some functions are beginning to come back on line, National Airspace System operations remain limited."

White House Press Secretary Karine Jean-Pierre tweeted, "The President has been briefed by the Secretary of Transportation this morning on the FAA system outage. There is no evidence of a cyberattack at this point, but the President directed DOT to conduct a full investigation into the causes. The FAA will provide regular updates."

Before leaving the White House with first lady Jill Biden, who was heading for a medical procedure, Mr. Biden told reporters, "I just spoke with Buttigieg. They don't know what the cause is. But I was on the phone with him. ... I told them to report directly to me when they find out.

"Aircraft can still land safely, just not take off right now. They don't know what the cause of it is, they expect in a couple of hours they'll have a good sense of what caused it and will respond at that time."

According to CBS News correspondent Nancy Cordes, when asked if there was any evidence of a cyberattack, he responded, "We don't know" -- even though Jean-Pierre had just tweeted that there is no such evidence.

Transportation Secretary Pete Buttigieg had tweeted earlier that he'd contacted the FAA about the outage:  

NOTAMs used to be available through a hotline but that was phased out with the internet. The alerts span from mundane information about construction at airports to word about urgent flight restrictions or broken equipment.

-- Kathryn Krupnik contributed reporting.