Good evening and welcome to the NewsHour. The nation’s air travel system has had another long and difficult day. By late afternoon, nearly 1,300 flights had been canceled and more than 8,000 delayed because of a critical system failure at the FAA.

的failure forced the FAA to call a nationwide halt to operations for several hours. Federal officials vowed to get to the bottom of an outage that disrupted travel plans for millions of people.

A wave of delays and cancellations rippled from coast to coast just as the nation’s airports were starting their day. The sudden shutdown left terminals filled with travelers with nowhere to go. The FAA’s ground stop order was lifted just before 9:00 AM Eastern Time, but the disruptions lingered for hours. Pat and Alison Cavanaugh were trying to fly out of Newark, New Jersey.

I’m really upset, but what can I do?

But it makes you kind of nervous. Is there something else that maybe we’re not being told right now?

的problem started late Tuesday when the FAA’s Notice to Air Missions system went down. That antiquated computer system supplies information that flight crews must have before being allowed to take off. This morning Transportation Secretary, Pete Buttigieg, said that initially at least there was no sign of a cyberattack.

的re’s been no direct evidence or indication of that, but we are also not going to rule that out until we have a clear and better understanding of what’s taking place.

Several hours later, he vowed to get to the bottom of what happened.

My top priority right now, now that the system is working again as of about 9:00 this morning, is to understand the root cause, understand how it could have led to this level of disruption and understand how to make sure that it does not happen again.

All this comes just weeks after massive holiday flight cancellations and delays wreaked havoc for days. That trouble was blamed on winter weather and Southwest Airlines’ outdated technology and reliance on a point-to-point system rather than using hubs.

的air travel system is heading back to a more routine schedule this evening, but today’s disruptions led to the first nationwide flight stoppage since 9/11, and it’s raised questions again about the reliability and vulnerability of our system. Our science and aviation special correspondent, Miles O’Brien joins us now to look at those concerns. Miles, always good to see you. Thanks for being here. Let’s start with this system, the Notice to Air Missions system that the FAA says went down late on Tuesday. What does it do, and how did it create such a mess?

So Notice to Air Missions, Amna, are the late changes to the game plan. You have published information on airports and what’s available and what frequencies are working and what navigation systems are working, but things change. And before you take off, you want to know if that runway is closed or if that frequency is not working or if there is some airspace closed. That is all encapsulated in these Notice to Air Missions formally known as Notice to Airmen. And they are sometimes minor little changes, sometimes very important. But most important, before an airliner can be dispatched on a flight, the pilots have to be briefed on what the NOTAMs are along their route of flight. So the good news is that the remedy for this problem is you just don’t take off. It’s not like a situation where something like this fails, airplanes fall out of the sky, but clearly causes huge disruption if it’s not working.

And we heard there Secretary Buttigieg saying they’re still trying to figure out what was the root cause. How did this happen? How do they keep it from happening again? What are some of the possible theories?

Well, those of us who follow the FAA closely are frankly not surprised to see a technological glitch, sadly. This is an agency that has historically been underfunded on its effort to modernize. It’s basically a system that was built after World War II, 1950s technology using spinning radar domes and UHF radio transmissions between the ground and pilots. It hasn’t moved into the space age, as it were, as it should have using satellites and computer transmission. And so as it has moved technologically and fits and starts into the modern age, there have been glitches along the way. Nothing quite like this one, but it is indicative of the fact that the agency needs to spend more on its infrastructure. The fact that it is so safe is quite remarkable to me, frankly, Amna. This is a testament to the men and women who make the system work in spite of its antiquated technology.

We did hear from travelers there, some of their concerns. Obviously, today was a big headache, right? Delays and disruptions, but some have safety concerns. And that bigger concern is, if a system like this could fail, Miles, are there other systems that you think are also vulnerable to similar failure?

That’s the lurking question. The redundancy is what makes the system safe. Flight critical systems, navigation systems, that beam which gets you down to that dark and stormy night onto that runway in 0-0, you want that to be backed up many different ways, of course. This system, which is part of the overall picture of redundancy, evidently didn’t have enough backups. Now, as I say, that didn’t cause a direct flight safety problem. It caused huge inconvenience. But you have to ask yourself, are there other problems lurking in this system where there needs to be more resilience? There needs to be another layer of redundancy, and I think it’s high time that Congress, the people in Washington focused on the FAA and thinking about it as a crucial piece of infrastructure and appropriating the right amount of money to fix it.

Luckily, today, just incredible delays and disruptions, not a safety concern. Miles O’Brien, our science and aviation special correspondent, thank you for being with us. Always good to see you.

不客气,Amna。