TWA FLIGHT 800 December 8, 1997 NEWSHOUR TRANSCRIPT

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Representatives of the federal government, the aviation industry, the pilots unions and victims' families assembled in Baltimore for a week-long hearing on the downing of TWA Flight 800.

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A RealAudio version of this segment is available. NEWSHOUR LINKS: November 18, 1997 The FBI concludes its investigation into TWA Flight 800. July 16, 1997 A year later the details of what felled TWA Flight 800, killing all 230 passengers on board, remain uncertain. November 19, 1996: Newsmaker interview with James Kallstrom FBI Assistant Director in charge of the criminal investigation. September 19, 1996: Investigators have yet to determine what caused the plane to go down. Now, perhaps, the investigation is taking a new turn. July 18, 1996: The beginning of NewsHour coverage of the crash of TWA Flight 800 . Browse the NewsHour's coverage of transportation. OUTSIDE LINKS National Transportation Safety Board FAA Office of Accident Investigation Check out the FBI main page.

TOM BEARDEN: It's been one of the most baffling and controversial accidents in aviation history. TWA Flight 800--a Boeing 747--was torn apart when its center wing fuel tank exploded on July 17, 1996. No such in-flight failure had ever occurred in the history of commercial aviation. The wreckage of the shattered plane was dredged from the bottom of the Atlantic Ocean and reassembled. But the National Transportation Safety Board still doesn't know why the tank exploded, despite the largest and most expensive investigation ever. No physical evidence has ever been found that clearly points to a cause. Even so, last December, long before all the evidence had been fully explored, the NTSB issued a series of controversial recommendations aimed at improving fuel tank safety.

JIM HALL, Chairman, NTSB: It was the explosive nature of the vapors in the fuel tank that allowed the blast--whatever its origin--to bring down Flight 800. We believe that mechanisms exist that could, even in the short term, reduce the probability of a recurrence.

A look at fuel tanks.

TOM BEARDEN: Behind the scenes experts have been arguing for months about fuel tanks--what the industry knew--or thought it knew--about what goes on inside one in flight. This is what a 747 center wing tank looks like when it's being built at the Boeing factory in Everett, Washington. It's a lot more than just a big aluminum tub. It's the size of a large livingroom, and is honeycombed with baffles, pipes, and supporting walls that divide it into chambers. It sits between the wings underneath the passenger cabin of a 747. A full fuel tank can't explode because there's no oxygen to support combustion. But as the fuel burns off, or when the tank hasn't been completely filled, the liquid fuel gives off vapors that mix with the air in the empty space. Engineers call that space the ullage; under the right conditions, the vapors can explode--if, and only if--there's something to set it off--no ignition source; no explosion. That's been the foundation of aircraft fuel tank design for nearly half a century. Richard Breuhaus is in charge of fuel safety programs at Boeing.

RICHARD BREUHAUS: The key in our design is to prevent the possibility of any occurrence of an ignition source inside the fuel tank. Again, we always operate under the assumption that the fuel-air mixture inside that tank could be flammable, and with that stated, we must make sure that there is no possibility that an ignition source would enter and ignite that flammable fuel-air mixture.

TOM BEARDEN: So designers have gone to extraordinary lengths to eliminate ignition sources. One of the most serious risks is from static electricity, which builds up in the fuel from simple friction as it flows through pipes and pumps, so fuel is pumped in gently and not allowed to spray inside the tank for the same reason. The pumps and valves that enter the tank from the outside all have grounding wires so static can't build up, and they're designed to automatically shut down if they overheat. The fuel probes, which measure the level of the tank, use voltages too low to make a spark big enough to cause an explosion. Higher voltage lines are isolated away from the tank. In all of modern airline history, only two fuel tanks have ever exploded without a clear cause. One was a Philippine airliner that blew up while sitting on the ground. The other was TWA 800. But Breuhaus still believes the design philosophy is sound.

RICHARD BREUHAUS: We have in excess of 200 million hours of operations on our airplanes in total. This is all models. We believe that the design approach is a very sound one. Having said that though, it's unescapable that we do have two unexplained accidents involving fuel tanks and because of that we are working very diligently both with the NTSB and FAA, as well as all of industry, to make sure that we have not overlooked anything.

TOM BEARDEN: That's why the board's recommendations were so controversial, precisely because they called the existing design philosophy into question.

JIM HALL: As you know at present the philosophy, the design philosophy, is to design the ignition sources out of the tanks.

TOM BEARDEN: Is that possible?

JIM HALL: Well, the record appears now that it is not possible.

TOM BEARDEN: But obviously something happened to Flight 800's fuel tank. And that set the NTSB to wondering if the aviation community really knew as much about fuel and fuel tanks as it thought it did. The board leased a 747 and fitted it out with instruments. They flew the same flight profile as TWA 800. They measured fuel temperatures after the plane had been sitting at a gate on a hot day and how much more heat the air conditioning equipment under the tank had contributed. They built scale models of the tank and set off small explosions inside to see how the blast propagates through the different compartments. Chairman Hall says the tests revealed that fuel behavior was more complex and variable than previously thought.

JIM HALL: The amount of information about the composition of Jet A fuel, at what point the vapors become explosive, what type of charge it takes, how much strength a particular charge it takes to ignite the vapors, what happens with that tank, you know, as it goes through the various altitudes, the vibrations, what effect that has on the fuel, whether there's mist or vapor, and all of this has been 16 months of my investigators' lives, trying to look at and understand this.

Objections from the industry.

TOM BEARDEN: So the board made several recommendations designed to reduce the flammability of fuel tanks. They said the airlines ought to use cooler fuel because it gives off fewer vapors and because it takes a bigger spark to set off cooler fumes. The NTSB also suggested filling the center tank before takeoff to reduce the empty space. And the board asked the industry to take a look at a system used on some military aircraft to render fuel tanks non-explosive. They're called inerting systems. On the Air Force's C-17 transport, for example, onboard systems extract non-flammable nitrogen from the atmosphere. Then it's pumped into the fuel tanks as they become empty. It displaces the oxygen and removes the possibility of an explosion. The industry reacted to all of these proposals with considerable rancor. United Parcel Service called them extreme and premature. British Aerospace criticized the board for "confusion and lack of understanding." Northwest Airlines said the recommendations would actually have a negative effect on safety. Michael Rioux is senior vice president for operations and safety at the Air Transport Association, the airline industry's major trade organization.

MICHAEL RIOUX, Air Transport Association: We don't know what the cause of the accident is, so why are we making recommendations on a solution set that may not solve the problem because we don't know what caused the problem to begin with. That's my concern. And I think the system has got to get back on track a little bit in that regard.

TOM BEARDEN: Rioux says the board's recommendations don't make a lot of sense. Cool fuel, for example. He says there's no way to chill fuel at any airport in the world, and that the tanks would still contain explosive vapors throughout the majority of the flight even if the fuel was chilled to zero degrees.

MICHAEL RIOUX: You always have some exposure either in cruise, climb, or descent, of being in the explosive fuel-air mixture ullage, and there's no--not one of those recommendations eliminates exposure at all.

TOM BEARDEN: As for inerting systems, the industry says they break down far too often to be used in commercial operations. Chairman Hall says the industry has been absolutely sure of things before and has later been proven wrong.

JIM HALL: At the beginning of this there were some experts that did not think that the tank was explosive, that it was impossible for it to explode; where there was this assumption that a lot was known, and once we got into it, that was not the case.

TOM BEARDEN: Last week the FAA responded to the board's recommendation, almost a year after they were issued. The agency said it had concluded improvements can be made that will greatly reduce, if not eliminate, the possibility of fuel tank explosions. But it did not say what those improvements were. Some of the board's recommendations were rejected; others were referred to a committee that will report back to the FAA in six months. These behind-the-scenes arguments about fuel tanks are now becoming public. Chairman Hall formally opened five days of public hearings on the crash of TWA 800 this morning in Baltimore.

Day 1 of the hearings.

JIM HALL: Good morning. I'd like to bring to order the National Transportation Safety Board public hearing. On July 17, 1996, a Boeing 747-131, operated by Trans World Airlines as Flight 800 to Paris, exploded and crashed into the Atlantic Ocean about 14 minutes after takeoff from New York's John F. Kennedy International Airport. All 230 persons aboard lost their lives. While the shock of this event has slowly abated, the horror has not. The National Transportation Safety Board launched the largest investigation in its history. Indeed, it is the largest investigation of a transportation accident in our nation's history. The FBI has recently suspended its criminal investigation of the crash, and we are here in furtherance of the NTSB search--not only for the cause of this accident but, even more importantly, for ways to make sure a tragedy such as TWA 800 never occurs again. In the nine months of the recovery effort there were 677 surface--dives and 3667 scuba dives, resulting in 1773 hours of bottom time for the divers. I hope all of you all can think with me and visualize the brave men and women who made those dives under those conditions to recover the loved ones and the wreckage. We all owe them a debt of gratitude. Fully 94 feet of the 747's fuselage was rebuilt, including the center wing tank, the heaviest structural part of that airplane. The reconstruction and detail lab work enabled our investigators to determine the sequence of events from the initial fuel explosion to the ultimate destruction of Flight 800. I would like to say a word to the family members of the victims, who are here with us today, or those who are watching the proceedings on C-Span. While all of us have felt enormous sympathy for your grief for many months, none of us can claim to know what you have gone through since the night of July 17, 1996. We can, however, make sure that we dedicate all possible resources to finding out what happened that night and doing what we can to assure it doesn't happen again.

TOM BEARDEN: The board heard testimony from the Navy on the hundreds of divers who labored to recover the wreckage, ending in extensive dredging of the ocean bottom.

JIM HALL: In your opinion, do you have any idea how much of the wreckage was recovered and brought to the hangar at Calverton?

MC CORD: My own guess off the top of my head is probably a good 98 percent, over 98 percent of the aircraft was recovered and most of it by a majority of that 97/98 percent by the divers.

TOM BEARDEN: John Clark, an expert in studying flight recorders and radar for the NTSB, presented his findings from his investigation over the last 17 months. He showed the board a series of animations that demonstrated how the plane split apart and fell to the sea.

JIM HALL: What do the various colors signify?

JOHN CLARK: The green line is the aft section of the airplane. It includes the wings, the engines, and the aft section. The yellow line is that 70 foot forward section that separated, and the red lines are the several parts of various sizes and weights from in and around the center wing tank.

TOM BEARDEN: Clark then showed an ocean view animation giving a detailed, actual time demonstration as to how his team concluded the plane exploded and fell to the water.

JOHN CLARK: At eight minutes and thirty-one seconds you will see the center wing tank explosion; the forward fuselage will separate a few seconds later; and the remainder of the airplane will climb and turn left. It will reach a peak altitude of about 15,000 feet 20 seconds later and start a descending turn to the right with increasing bank angle. The flight will transition into a steep accelerating descent. Just before water contact you'll see a big fire ball as the left wing starts to break away from the fuselage. Mr. Chairman, we believe we have accurately defined the motion of the airplane, and we've correlated all of the data. We see no evidence of any unusual events, and we also know that many parts separated immediately at the time of that first explosion.

TOM BEARDEN: He then showed a chart demonstrating how the flight and voice recorders stopped working.

JOHN CLARK: The total time from side to side represents about 2.2 seconds. A loud noise appears here, and it is the last signature picked up by the cockpit area microphone. It is present for about 1/10 of a second, and ends when the CVR quits at 8:31 and 12.5 seconds. We believe this signature is the result of the exploding center wing tank.

TOM BEARDEN: Chairman Hall opened up the discussion for questions from the other parties to the investigation, including the Airline Pilots Association.

SPOKESMAN: Could you also discuss for me why the nose section reaches the ground so much later than the aft section, and could you discuss a little bit the parameters that went into that equation.

JOHN CLARK: Well, there's a difference in the weight of each section and the drag, or the size of the shapes. For example, the nose section is relatively light, with a large frontal area. And it would be similar to putting your hand out of a car window and feeling a lot of pressure. The aft section of the fuselage with the engines and the tanks and the fuel is more dense, if you will, and once it started down and the nose pointed down would pick up speed much more rapidly.

TOM BEARDEN: The board also heard testimony from Richard Bott, a Navy expert on missile damage, who stated flatly there was no evidence of either a bomb or a missile impact on the 747.

RICHARD BOTT: It's very easy to determine if that happened or not simply by finding a single piece of wreckage with high velocity impact damage on it. There was none found in Calverton, despite over 95 percent of the aircraft being recovered. There are no places on that aircraft, no places of missing structure that are large enough to contain enough damage that have not been recovered. In other words, there's no large areas of missing structure on the aircraft that could contain all the damage from the warhead. There's small pieces missing from random places throughout the structure, none large enough to be the central location of a missile impact. So that--the possibility that a missile with a live warhead impacting that aircraft is--is--is conclusive evidence that it did not occur.

TOM BEARDEN: NTSB aircraft expert Jim Wilde said every piece of the wreckage was examined minutely.

JIM WILDE: I can safely say that this is some of the most examined metal there is anywhere in the world, especially between the nose section and the aft section, literally every inch, every quarter inch of the fracture in the fuselage skin, in the frames, in the stringers, in the center fuel tank, in the wing center section, every inch of that structure has been examined in great detail.

TOM BEARDEN: Late this afternoon the board heard testimony on the forensic evidence revealed by the examination of the victims. Medical experts said they too could find no evidence of an explosion based on the lack of any pattern to the injuries sustained by the passengers. Medical consultant Dr. Dennis Shanahan said most of the victims were probably killed instantly.

DR. DENNIS SHANAHAN: We believe that all these individuals were almost immediately incapacitated. Whether they're dead or not, it is highly unlikely they were conscious or aware. And so that was the determination we had made. But now the reason for doing that was to try to find areas of the cabin that might have been less damaged, and, if less damaged, it gives us some information as to what the sequence of break-up was and the severity of that particular break-up.

The cause may never be known.

TOM BEARDEN: The board may not conclude its work for still another year, and even then the cause of the accident may never be completely resolved. Even so, Chairman Hall says the lack of a definitive finding is no reason for the board not to call for changes.

JIM HALL: But irrespective of finding that an ignition source and being able to point to it, I think we will be able to point to safety advances that have begun and will continue to make the entire fleet much safer against the very rare fuel-air explosion that we have seen in the past.

TOM BEARDEN: The hearings on the crash of TWA 800 are scheduled to continue through Friday.

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