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American Morning
Wake Turbulence Can Be Very Dangerous
Aired November 16, 2001 - 09:34 ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
PAULA ZAHN, CNN ANCHOR: Federal crash investigators looking for the cause of the crash of American Airlines Flight 587 tell us that the flight data recorder retrieved from the wreckage shows clear signs the Airbus flew through the wake of another plane not once, but perhaps twice. So what is wake turbulence, and how dangerous can it be for pilots? Well, Miles O'Brien took a wild ride yesterday to learn more, and he joins us now with the details. Good morning, Atlanta -- you -- Atlanta. Good morning, Miles. You have flown for years. Now, you have flown in turbulence before, haven't you?
MILES O'BRIEN, CNN ANCHOR: I have, I have -- I've never deliberately put myself into wakes like I did yesterday. We did a couple of maneuvers that were very startling, literally leaving our hands off the controls and watching what the plane does, and it's quite dramatic. You know, no matter what size a plane is, Paula, it generates a swirling trail of turbulent air that persists for several minutes. Airplanes fly through each other's wakes all the time. You've probably flown through a wake in an airliner, and probably chalked it up to clear air turbulence or something. But, to find out why wake turbulence can become something more serious, I strapped in and flew right into the wake.
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Tailgating in the air can lead to an upsetting outcome. We're flying above Houston in a pair of small single engine trainers hot on the trail of wake turbulence.
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DON WYLIE, AVIATION SAFETY TRAINING: Now, get out of it so we can see him. See what it does to him?
O'BRIEN: Oh, yeah.
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O'BRIEN (voice-over): Don Wylie is my guide into the vortex. He owns an outfit called Aviation Safety Training where they teach pilots how to bring their planes back from the brink. And as I discovered, flying through another plane's wake can lead to trouble very quickly.
(BEGIN VIDEO CLIP)
WYLIE: How do you like that? That's something, huh?
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O'BRIEN (voice-over): In little more than a second, our plane was turned on its side at a 90-degree bank as it flew through the powerful cyclones that trail behind the wing tips of every aircraft.
(BEGIN VIDEO CLIP)
(on camera): So, you're talking about kind of a mini tornado almost.
WYLIE: Sort of a mini horizontal tornado.
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O'BRIEN (voice-over): The tornadoes, known as vortices, are stirred up by a wing slicing through the air. It's called wake turbulence, and it's hard to predict what will happen when a plane flies through it.
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O'BRIEN (on camera): Is it scary flying through a wake?
WYLIE: Yes. Well, scary depends on if you're prepared for it. Remember, the pilot flying the airplane is low expectation of upset over another category, but he's not expecting -- he or she is not expecting an upset, especially lowest level climbing out, lowest level approaching the runway.
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O'BRIEN (voice-over): American Airways 587 had just taken off, climbing and gaining speed when it apparently flew through severe wake churned up by 747 less than two minutes ahead.
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JOHN WILEY, AIRLINE PILOT: It may vary with the weight of the aircraft, but generally if you're taking off behind a heavy aircraft, personally, I have no -- no rush to jump into the air.
(END VIDEO CLIP)
O'BRIEN (voice-over): The heavier the aircraft, the larger the wakes. And they linger. In test flights, engineers measured vortices stretching 8 miles long. The unseen danger can lurk much longer than pilots might think. In September of 1994, a U.S. Air 737 spun out of control and crashed on approach to Pittsburgh after flying into another plane's wake. No one survived.
(on camera): Most aviation experts agree it is highly unlikely wake turbulence alone could bring down a wide-bodied aircraft like an A-300. In fact, in most cases, it is a series of unrelated factors that come together to create a recipe for disaster. (voice-over): In the U.S. Air crash, the rudder was faulty, hampering the crew's ability to recover. And in the case of American 587 there are also many questions about the tail fin and rudder, which sheered off the plane in the air.
WILEY: Wake turbulence can be dangerous, no doubt, but did wake turbulence cause this one? Again, I have to come back and say I think it's a contributing factor. We have to figure out why the vertical fin left the airplane.
O'BRIEN (voice-over): While federal investigators try to answer the questions many pilots wonder if it isn't high time to reconsider the two-minute enter value between departures.
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WYLIE: In a perfect world, we'd have at least three minutes separation between airplanes. Just having stated the characteristics of these wakes. It's someone else's area to figure out if the industry can bear that kind of separation.
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O'BRIEN (voice-over): More time between departures means more delays for passengers. But for pilots, it may mean just enough time to avoid trouble.
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O'BRIEN: Now, yesterday the National Transportation Safety Board indicated that the first cut, if you will, of the flight data recorder indicated that perhaps American 587 encountered wake turbulence twice.
Let's take a look at a graphic very quickly here to try to explain how that might have occurred. If you look very closely at this graphic we put together, it indicates how the vortices spin off the wing tips of any given aircraft. And what happens is, they go in opposite directions. One side counterclockwise, the other side clockwise, as seen here. And what can literally happen, Paula, is a plane can fly into this side, be spun in this direction into the opposite wake, hit that wake, and then actually be sent back. It's sort of a -- a trap if you will.
And then -- although we don't know exactly if that's what happened to American Flight 587, the fact that they're indicating that the plane hit the wake twice could be explained by that phenomenon. Paula.
ZAHN: Yeah. Miles, there was something in the "Wall Street Journal" I found a -- really interesting this morning. And they said that they learned some information that suggests that the pilot of that jet might have actually over-controlled the jet as it hit those bouts of wake. What is that mean exactly?
O'BRIEN: Well --
ZAHN: What would the pilot have done wrong if that ends up being the case?
O'BRIEN: A couple of things to consider here. First of all, very early and I'm hesitant to besmirch the reputations of those pilots. We don't know what they were encountering, and what heroic measures that have been trying to take, and the possibility that the tail was off. All that aside for a moment, it is important to point out that airline pilots in general are taught to avoid these upset scenarios, these situations when a plane gets upside down or close to being upside down as opposed to getting a lot of training in how to recover from them.
And so, there are occasions when these pilots end up severely tilted or inverted, where they may not have a lot of training in that regard. So, it's something the airlines have been looking at. It's something that's very difficult to replicate in a simulator. They do most of the practice, if you will, in these computer simulators. You don't get the feel of being upside down when you're in a computer simulator, and there's some who suggest they should spend more time figuring how to get back right side up when they're hanging by their straps.
ZAHN: Boy, your report was really helpful in understanding what these pilots might have been up against. Is that the worst turbulence you've ever encountered flying? Because, you've obviously were putting yourself into it.
O'BRIEN: It was -- yes, it was an eye-opener. There's no question. And, you know, when we went through that one scenario where we sort of let go of the controls, and flew into that wake, and in literally a second we were 90 degrees up on edge. It really made it -- brought it home to me. Because you can imagine American Airlines Flight 587 was turning in 30-degree bank already. If, in fact, it hit a wake which sent it more in that direction, that plane could have been inverted or upside down in just heart beat.
ZAHN: Frightening to think about. All right, Miles, thanks so much. Have a good weekend. Going fly thing weekend?
O'BRIEN: I am. Tomorrow.
ZAHN: In clearer air, and cleaner air, I hope.
O'BRIEN: Absolutely. We're going to do a nice smooth flight.
ZAHN: All right, take care.
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