"This is very unusual. This is really almost unprecedented in U.S. aviation history," said aviation professor, Jeff Price at Metropolitan State University of Denver.
There were widespread delays at Denver International Airport and around the country. It was due to a FAA computer failure, which happened at the start of the morning and affected about 60 flights.
Aviation consultant, Mike Boyd of Evergreen told CBS News Colorado, "This is not a minor one either or Southwest being the Grinch that stole Christmas this is a safety organization that couldn't deliver."
In effect, it shut down the safety roadmap that pilots must read for any alerts en route to their destination its called a "Notice to Air Missions System" or NOTAM System.
But what caused the outage? The answer was not immediately clear.
"Even if it was a cyber attack or not sure they know that, but that doesn't seem to be the case right now. It just might be a case of us are more or some other IT-related failure," he said.
Even President Joe Biden was in the dark after speaking to his secretary of transportation.
"I just spoke with Buttigieg. They don't know what the cause is," President Biden told reporters.
The question is what will it take to prevent this from happening again?
Mike Boyd believes the issues should be addressed and strong action must be taken.
"Well, congress is going to get involved that's a comforting thought. The real issue is you have to have some accountability for its failure. Heads should roll," Boyd said.
Flights at DIA were disrupted for over two hours.
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