SCOTT DETROW, HOST:
The FAA has now lifted its nationwide ground stop, but when it was in effect earlier today, there were still planes in the sky, and pilots had to navigate the situation at a moment's notice with little information. Earlier tonight, when the ground stop was still in effect, I spoke to John Cox, a former commercial airline pilot and an aviation safety expert.
If you were flying a plane this afternoon, this evening, what would be going through your mind when you got this update?
JOHN COX: I think the first thing would be, let's try to find out what we can do to stay in communication. There are backup frequencies. There are other pilots that we can talk to. And those are going to be the first things that we're going to do. I'm going to look for data link capability through a system known as ACARS or CPDLC and see if I can get the necessary information via data link. So there's several redundancies built into the system.
DETROW: I haven't seen any indications from radar or from official announcements or from reporting at airports that they're doing what they did on 9/11 and making planes land as quickly as possible at the nearest airport. Is that an indication to you that they're not concerned about the planes that are in the sky or that they just think, keep them on the routes as is?
COX: They've said very specifically that the aircraft that were en route were going to continue to their destinations. They amended that later and said there might be some airborne holding. And these are at the major congested airports. One of the things that is becoming an increasing issue is the physical ground space to put the airplanes, so they - may be some diversions. But it says that they're not concerned from a security standpoint, that it is just the massive amount of aircraft in the skies landing safely at a place - at an airport that can actually handle them.
DETROW: Yeah.
COX: And so with there being very few departures, these airports are backing up. O'Hare, Reagan National in Washington are two that have said that they're really short on ground space.
DETROW: OK. I mean, from what we know right now, do you have any guesses about what the problem could be? - a problem that, you know, flights in the air are continuing, as is, as you just explained, but a nationwide ground halt? Like, any sense what could be going on here?
COX: No. I think right now, as any good investigator will tell you, in the early hours, the thing you want to do is gather evidence.
DETROW: Yeah.
COX: They're going to be looking for commonality between these en route traffic control centers because the system's designed not to have a single-point failure. And yet today, something happened, and we got a cascading of issues. So...
DETROW: Yeah.
COX: ...Where's the origin of that? How did it proliferate from one en route traffic control center to another? Those are the sorts of questions that they're going to focus on in the early hours.
DETROW: Can you just take a step back and help us understand how often pilots are talking to those regional air traffic control centers when they're in the air, and how much the air traffic control centers are communicating with each other about the routes?
COX: It's pretty constant. The - once you're in the cruise phase of flight, the communication level drops, where you're literally - you're talking to a controller, and you tell them your altitude, and if things are quiet and they want to leave you on your route, the next thing you'll hear - some eight, 10, 15, 20 minutes later - is to contact the next sector in the center airspace.
If, on the other hand, you're flying overhead a busy airport, and there's a lot of traffic, and there's a lot of clearances or routings that are being changed, then it can be a pretty constant flow of information to and from the air traffic controller. One pilot may not be talking to them all the time. There may be 15 pilots on frequency, and if so, one of those 15 is talking with a controller pretty constantly.
DETROW: John Cox, you have that classic reassuring pilot voice, as I'm sure you know. And I'm wondering - that makes me wonder how would you communicate this to passengers in the air if you had been piloting a flight tonight? What would you say? How would you explain it?
COX: I think I would explain it that we are experiencing some issues with the air traffic control system, that there are contingencies in place, and we are following them. We are guaranteed separation from other aircraft by following those procedures. Things are going to be slower, and they're going to be slower once we get on the ground at our destination. So I would ask them to be patient and to let the system work in the way that it's designed and that I would ask them then to sit back and relax and enjoy the flight.
DETROW: (Laughter) Last question. What are your two or three biggest questions you have right now based on the sparse public information we've got?
COX: Where's the commonality in the center? How could one problem proliferate between different air traffic control centers? Is it something that is new? Is there a new system that's been implemented? Are there common areas for fiber optic cables or anywhere? I'd be looking for commonality...
DETROW: All right.
COX: ...First. Then secondly, I think the response - the people responsible in the FAA command center - how was their decision process? And I would review that as a lessons learned sort of thing. And then thirdly, going forward - and probably the most important question - is how do we put the system back together?
DETROW: John Cox, former commercial airline pilot, and an aviation safety expert, thank you so much.
COX: My pleasure. Transcript provided by NPR, Copyright NPR.
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