Some Thoughts about Deadly Departure
by
CAP PARLIER
The book in question:
Negroni, Christine. Deadly Departure: Why the Experts Failed to Prevent the TWA Flight 800 Disaster and How It Could Happen Again. New York: HarperCollins Publishers, 2000.
Negroni makes a valiant attempt to bring life to the tragic event of TWA 800. However, once passed the delicate mixture of fact and fiction, this book becomes a case for nitrogen-inerting systems for fuel tanks.
The weakness of her argument is in the biased and incomplete study of the engineering issues associated with such questions. By her choice of words and logic, the casual reader is left with the impression that the OEM's, in this case and especially Boeing, are cold, heartless, money-grubbing, nameless businessmen only interested in the money and not particularly interested in public safety. Whether this impression was Negroni's intent or not, it is her regrettable slant to a very important topic.
The most fundamental design philosophy across the entire industry from big to little has revolved around a recognition that fuel is by definition flammable and as such potentially explosive given the correct conditions and given an ignition source. Thus, design elements include but are by no means limited to tank structure, sealing, venting and especially bonding. All tankage since the 1960's is electrically bonded to ensure electrical charges of any source including lightning will not arc within the tanks. Flame arresters have been used for years in venting and tubing, and were used in N93119 to prevent external flame walls from entering tankage. Extensive testing is done at the component as well as system levels to ensure the specific design and manufactured system achieves the desired performance.
Further, electrical systems in all their elements have been seen as a primary potential ignition source. As such, electrical cabling of any kind is routed around fuel cells. Cabling penetrates fuel cells only as a last resort, and then contained in aluminum tubing conduit completely sealed from the cell environment. Electrical wires that may be required to provide quantity measurement are contained within the probe structure, not exposed to the fuel or fuel-air vapor. For Negroni to leave the reader with the impression that bare wires with rotting/cracking insulation were contained in the CWT is wrong. Further, fuel pumps are commonly designed so the only the mechanical portion of the pump is internal to the tank. The electrical components are usually outside the tankage. Where electrical elements must go inside tankage they are contained within the pump structure.
The physical reality is all engineering designs, since time in memorium, have been based on the best thinking at the time. The standards used today are better than the standards used during the design and manufacture of N93119. So, application of today's knowledge is wrong and otherwise misleading. Whether we like it or not, aircraft design, probably to a greater extent than any other transportation method, is an art of compromise. If she only knew how agonizing it is for the engineers during the design and manufacture process, she might have been a little more even handed. Hours, weeks, months are spent over minute details trying to make everything fit within the design or certification standards. The truth be told N93119 was designed, built, certified and maintained to the applicable standards pertaining to that vintage aircraft as modified by applicable service bulletins, airworthiness directives and customer-directed modifications. To take this path of argument to its extreme, take the actual case of a Beech Model 18 [a twin, radial engine medium transport of WW II era; this one actually built in 1939] that crashed on takeoff near Indianapolis. As I recall, the aircraft had a pilot and 10 parachutists aboard when it stalled immediately after takeoff, flipped on its back, crashed and burned killing all aboard. As always, suits were filed claiming negligence on the part of the OEM. The plaintiffs stated that many safety improvements has been identified in aircraft design that the manufacturer knew about and willfully did not incorporate them; among those improvements was a fuel cell, N2 inerting system. The sad reality was the aircraft was overloaded above maximum gross weight and well out of the center of gravity limits; I know of no airplane that would fly in such conditions. And yet, the families went after the OEM using the press to make the company out to be this cold, money-grubbing, almost malicious pack of thieves and ogres. N2 inerting would have had zero benefit or affect on the outcome that accident, as well as all the other elements. And, there are many more examples just like the Beech Model 18. This retrospective application of modern technology is wrong.
Negroni has reasonably presented the philosophy of N2 inerting systems including the capabilities of OBIGGS [and an unmentioned version called OBOGGS]. These principles have been known for 40 years and used in limited applications predominately military aircraft for 30 years. The bottom line is N2 inerting systems work. It must be understood that they work relative too elimination of the fuel-air vapor common in every fuel cell that is other than full. N2 inerting does effectively eliminate internal tank ignition potential from virtually any source including ballistic penetration. Inerting systems help with in-tank events but cannot help with tank ruptures like crashes. As in all cases, all the elements are balanced against the failure modes analysis to find the proper compromise between risk, weight, cost, performance, and compatibility.
p.136 Missile discussion is only partially correct. The statement the missile would have to be 10 feet long is not correct. A Shoulder-Fired Infrared Missile [SFIM] fired beneath an aircraft on that well-defined flight path would burn for 6 seconds; the smoke trail evident but would be difficult to see at dusk or dark. While an SFIM would be near it's kinetic limits, the damage potential is still substantial; the missile would not necessarily have to impact on a vital component; a single, tiny, high-velocity fragment hitting the skin of the CWT would be sufficient to ignite the fuel-air vapor. A 10-foot missile, like the SM-2, could not have been involved; the momentum of the missile alone would have done significant damage that would be impossible to overlook or cover-up. There is absolutely no evidence that could even remotely indicate a missile of that size. The argument fails to recognize the real but diminished capability of SFIM weapons at that altitude. A commercial jumbo-jet on climb out is about as benign a target as possible flying a straight path and climbing even at 13,000 feet.
p.177 DC-8 crash in Anchorage, AK, on 27.11.70. Citing this accident as justification for N2 inerting system is flat wrong. Once a tank opens up in a crash sequence, the process of flammability and ignition fundamentally changes. This segment is technically misleading.
p.178 Again, using the PanAm-KLM runway incursion accident at Tenerife, in the context of N2 inerting systems and an implied connection to TWA 800 - an in-flight breakup - is flat wrong.
p.181 B-720 NASA crash test. She ignored the fact the pilot screwed up the approach flying remotely and the aircraft crashed well outside of test condition parameters. If anything, it was a demonstration that any crash can be made to be catastrophic and sensational. If examples like this are to be quoted, the author should really understand what happened and why. The test had noble intentions and was well thought out, but unfortunately, the remote pilot did not handle the vehicle properly. An N2 inerting would have had zero effect on the conflagration that occurred, but that fact was not mentioned. Once the limit of survivability is reached, the only known ways to survive those events are bailing out or using an ejection seat and descending to the ground by parachute - not practical in commercial air travel.
p.191 "Of course, nothing's perfect." By definition, this is a true statement. An airplane is the embodiment of compromise. Tradeoffs must be made in virtually every system on an aircraft. Focus on cost rather than value. What value would it have cost vs. benefit? What is acceptable safety? Deal in livelihoods. If anyone tries to use absolutes, especially in aircraft design, the problem becomes unbounded.
p.200 single point failure. Getting hit by a meteor is a single point failure; discussions of single point failures are incomplete without the associated likelihood or frequency of occurrence. In fact, as presented, this level of discussion is inflammatory, inaccurate or at least incomplete, and certainly not constructive toward greater safety. Once again, this brief exchange can leave the casual reader with the impression that there are single point failures in the fuel system that could lead to or be the cause of TWA 800.
p.217 sensational and irresponsible. Boiling this event down to money-grubbing manufacturers simply concerned about costs is truly irresponsible, yellow journalism. Has she ever tried to understand the engineering process and how bloody difficult the job is? The wiring issue is not so simple. And, what does aging wiring have to do with TWA 800? She tries to make a connection between the aging wiring question and the ignition of the fuel-air vapor in the CWT. In reality, even if the in-tank wiring had arced, it would have been contained inside the probes or conduit. A single electrical arc on any wiring inside a fuel tank could not be the source of ignition.
p.224 Tower Air. Indeed. However, what is not said or explained is that even with a short of the FQIS, even internal to an in-tank quantity probe, at least one or two more associated failures would be required for an ignition source to be present. It is through this omission that the casual reader may very well view an FQIS short as the cause, when in fact, a short of the FQIS could not by itself cause such an explosion.
p.232 "With so much at stake, Boeing will try to influence the process every step of the way. Some charge it already has." Now, what is the reader supposed to take from this statement...that Boeing will help the process...or, that Boeing will resist the process every step of the way. Perhaps the statement is meant to imply obstruction of justice. To think that Boeing would blindly allow others to dictate what it must do and how much it must spend is ludicrous. Boeing is an honored, responsible company that makes some of the world's best airplanes. The company has a long history of going the extra mile in the interest of safety. For an author to suggest in however soft terms that Boeing will or would resist safety improvements to their products is slanderous, if there was such a thing for companies. What must also be kept in mind, the FAA and the NTSB are not perfect by any stretch of the imagination. There must always be a balance, thus Boeing's 'influence' within the process is a mandatory requirement to achieve some semblance of balance.
In many respects, Deadly Departure is a very good book dealing with a controversial and often emotional debate surrounding TWA 800. Negroni has done a reasonable and perhaps even an excellent job compiling direct and indirect information related to the July, 1996 event. It is unfortunate, however, she did not make an attempt to understand the engineering process as it relates to these questions and to ask a few more questions to appreciate the possibility of the missile theories. I hope she can also accept that there are many of us who are not wild-eyed conspiracists, who do understand engineering and its processes, and desperately want to understand the physics of what happened to TWA 800.
The long and the short of it, this event will remain the most controversial aircraft event for many years to come. Negroni's book does not provide answers or solutions. It does provide further insight into the events associated with this event. To many, her presentation is a more satisfying conclusion as many journalistic reviewers have noted. She tries to put the bizarre investigatory anomalies into perspective. However, she fails to ask the most probing questions:
Why do eyewitnesses continue to insist they saw a missile-like object rising from the water beneath the doomed airliner?
Why is the eyewitness data, to this day, still withheld from the public?
So many why's about what happened prior to the ignition of the CWT of TWA 800.
The title alone is the most condemning - "...the Experts Failed to Prevent...." Even if Negroni is 100% correct in her reporting, the conclusion does not warrant the public indictment explicit in the title words. What if she is wrong and one of the missile theories is correct? Is she really that confident in what she has been told, and more importantly, what she has failed to ask? The title is the most telling to her lack of understanding or even appreciation of the engineering involved in aircraft design and manufacture - a very sad note.
The controversy will continue.
This page was last modified: 6.May.2000
