|INVESTIGATING FLIGHT 587|
November 14, 2001
NTSB Chairwoman Marion Blakey discusses likely causes of Monday's plane crash in New York.
MARGARET WARNER: The National Transportation Safety Board has the lead role in the ongoing investigation. And NTSB Chairman Marion Blakey joins us now. Welcome, Ms. Blakey.
MARION BLAKEY: Thank you very much.
MARGARET WARNER: You just had your daily briefing today and you had some good news about the flight data recorder, the damaged one. Tell us about it.
|Examining the "Black Box"|
MARION BLAKEY: Yes, we were quite concerned because we recovered the flight data recorder yesterday. But when we found it was damaged, there was real concern that we wouldn't have the vital electronic data that it gives us.
So we sent it down to Florida to the manufacturer, and there we've had them read it out. We've now got the information and we're going to be able to compare notes.
MARGARET WARNER: How quickly will that information be public?
MARION BLAKEY: Well, as soon as we can make it public. We are really committed to bringing every piece of factual information that we can verify out into the public eye, because we want to quickly get to the bottom of the cause here.
It's a complicated investigation, though, I should caution you, so I don't know how quickly we're going to be able to come up with a concrete cause. It may take months, it could take many months.
MARGARET WARNER: Now, today at the briefing you made it very clear that you all are really zeroing in on the tail fin of this plane, which broke off before the crash. Why? Why is that becoming such a focus?
MARION BLAKEY: Well, when you look at the flight path and you look at what appears to at least be the evidence that we've recovered, you find you have transponder responses from the aircraft right up until the point where you look down and see in the debris field where we recovered key parts, the vertical stabilizer as well as the rudder were two pieces that were right there when the last radar transponder response occurred before the aircraft in fact hit the ground moments later.
But it does give us an indication it was one of the vital pieces of the aircraft that certainly came off before impact.
|A "vertical stabilizer"|
MARGARET WARNER: You use the phrase, word "vertical stabilizer." We're going to puts up a little graphic. Explain what the tail fin is and what parts the vertical stabilizer and part is the rudder, is that right? And what does each piece do?
MARGARET WARNER: So the rudder essentially pivots like this, you can't see me, but on the back of that tail fin?
MARION BLAKEY: It does. It pivots vertically on the back of the fin, precisely.
MARGARET WARNER: And are they so essential that if this whole apparatus were to somehow become unhinged from an airplane that the airplane would just lose control and could crash, would crash?
MARION BLAKEY: It's a devastating loss to an aircraft to lose essentially the tail assembly and the vertical stabilizer, there's no question about the fact that that would be a vital loss in terms of maintaining control an being able to land an aircraft.
MARGARET WARNER: So where are you in figuring out what caused the whole tail fin to come off?
MARION BLAKEY: Well, we're certainly looking, as you point out, at this tail assembly, at the vertical stabilizer. It's interesting because the stabilizer is made of composite materials; as you know for many, many years most aircraft were made out of aluminum and other metals.
Recently we have been seeing more aircraft, and recently by the way is not that recent, the military has used composite materials for many years, and this particular aircraft has been out there in the fleet for over 20 years.
But that nevertheless is somewhat recent history in terms of a composite structure. So we're looking at what kinds of issues there may be from that standpoint.
MARGARET WARNER: Now, my understanding is that the bolts, I don't know if I'm using t right word, but the things that attach this tail fin to the fuselage, at least the bottom of those bolts were still in the fuselage, so it wasn't loose bolts, is that right, but that the sheering took place above that?
MARION BLAKEY: I probably should be careful because we've got inspectors out there now at the hangars looking at all this much more carefully than I was able to do this morning when I was over there.
But there is no evidence that bolts came out or that there was a maintenance problem in terms of missing bolts, you're quite right about that.
|Possible factors that caused the crash|
MARGARET WARNER: Now, you all talked a lot today at the briefing too
about wake turbulence. And last night when you talked about what had
come out on the voice recorder that one of the pilots, I think it was
the lead pilot, the captain, said something about a wake counter. Explain
what that is, that phenomenon and what might have caused it in this
A similar phenomena occurs in the air when you have one aircraft that moves through the air and another one comes behind it. It's very common, it's not in any way in most cases a endangering phenomena.
But the aircraft that was in front of the American Airlines flight was a 747, a JAL flight, and we know from just looking at the pattern and we've tracked that in terms of the radar data, but when you look at the pattern of those two flights, it's very clear that you could get a significant wake phenomena from the JAL flight that the American Airlines flight coming behind had to flight through.
Now, many times that would be experienced as simply turbulence, perhaps severe turbulence, so it's early for us to know if that really a contributing factor to this accident, or not.
But we are looking at it because there's no question about with the wind direction and that JAL flight that we have to take that seriously.
MARGARET WARNER: Do you know yet whether the two planes always maintained, it was only 2 minute 24 seconds of the American Airlines flight, but whether they always maintained the required distance and time between them, to minimize the turbulence?
MARION BLAKEY: Well, what we do know is that the controller okayed the American Airlines flight to take off at the appropriate point. In other words, it was within the stipulated parameters, which would be two minutes behind the JAL flight, or a 4-mile separation.
Either one of those is appropriate in terms of the way the controller looked at when that American Airlines flight should take off. That did happen.
What appears to be the case as we look at the radar data is despite the fact that the controller okayed the JAL flight and then two minutes and 20 seconds later okayed the American Airlines flight, it may be that that JAL flight was a little slow on the takeoff and there may be a little bit less time as we're looking at those flights behind each other.
But nevertheless there's nothing that indicates that there was an error, because, as I say, it was more than 4 miles there at that point also.
|Keeping everything in perspective|
MARGARET WARNER: Is there a precedent for an accident involving two huge planes like this being caused by wake turbulence?
MARION BLAKEY: It doesn't happen often. Many years ago there was a military flight that apparently did experience this catastrophically, and we also saw this with a crash that happened outside of Pittsburgh several years ago, a USAir flight.
MARGARET WARNER: It's fair to say, is it not, that you have been able to rule out some early theories that were, you know, propounded, like an explosion in the engine, or a bomb? What have you been able to eliminate?
MARION BLAKEY: Well, I would say at this point we're not eliminating anything because it's early in the investigation. I know that we all want answers, we all want to know what happened here.
But we're determined -- certainly I'm determined in terms of the way we're approaching this investigation that we are going to look at every scrap of evidence and see whether there's any evidence of sabotage of any kind of criminal activity.
So we'll continue to look at things that way, as well as look at them from the standpoint of what might have gone wrong from a structural standpoint, a performance standpoint, any problems with operations, maintenance, all these various factors that you have to consider.
But to go to your point, there is no evidence to this point of any bomb, of any explosion, of any kind of criminal activity. And when we analyze the voice recorder, the cockpit voice recorder, there are only two voices in the cockpit, the pilot and the co-pilot.
MARGARET WARNER: Marion Blakey thank you so much.
MARION BLAKEY: You're welcome.