TWA 800 and Electromagnetic Interference: Work Already Completed and Work that Still Needs to be Done

Editors’ note:The following is a Web-only supplement to a series of articles published by Elaine Scarry in The New York Review of Books.

In July of 1998, the National Transportation Safety Board announced that it would attempt to assess the strength of the electromagnetic environment surrounding TWA 800 the night it fell. In order to do this, it would enlist the help of two agencies: the Joint Spectrum Center, whose work is specifically dedicated to solving problems inside the military that arise from joint use of the electromagnetic spectrum, and the National Aeronautics and Space Administration (NASA), some of whose scientists study the ways electromagnetic interference can affect civilian planes and spacecraft.

A three-stage process followed, each stage building on the foundation laid by the stage that had preceded it. In August of 1999 the NTSB compiled and forwarded to the Joint Spectrum Center a list of sea- and aircraft in the vicinity of TWA 800. The Joint Spectrum Center, limiting itself to the transmitters on this list (as well as to its own list of fixed transmitters on land), then calculated the signal frequency and strength of the land, sea, and air transmissions at the surface of the plane. Its formal report, “TWA Flight 800 Electromagnetic Environment,” completed in January of 1999, identified forty-five transmitters whose signal strength at the accident site was higher than one volt per meter (the threshold figure the Safety Board asked them to use).¹ NASA then took the Joint Spectrum Center figures and analyzed them in order to determine whether they were strong enough to have provided the ignition source for the central fuel tank explosion on TWA 800; NASA concluded they were not.²

Each of the three stages of work enumerated above broke new ground. First, as the Safety Board noted at its August 22-23, 2000, hearing, though it had previously looked at questions connected to electromagnetic interference in navigation and communication, this was the first time it had ever explored the way in which electromagnetic interference might act as an ignition source. Second, this was also the first time that the extraordinary resources of the Joint Spectrum Center had ever been called upon on behalf of commercial airline passengers³ : in the past, its resources had been dedicated exclusively to military planes⁴ or planes carrying high government officials.⁵ Third, as NASA’s formal report itself states, in the course of NASA’s work on behalf of TWA 800, their scientists developed a new method of analyzing electromagnetic interference from sources external to the plane that they hope will provide an important tool in future inquiries.⁶

These innovations have been appropriately saluted and placed in the public record by the agencies who carried them out. The article that follows below, while cognizant of these important achievements, will focus on the incompleteness of the work carried out on behalf of TWA 800. It will explain why the projects so far undertaken by the Joint Spectrum Center and NASA should—despite their virtuosities and complexities—be regarded as extensive preliminary studies rather than as final studies, why the work already accomplished needs to be supplemented by additional work. The fact that two other large passenger planes have fallen, or had their first sign of trouble, in the same region in which TWA 800 fell provides strong incentives for carrying out additional work, and those incentives have been examined in detail in Parts I and II of this article⁷ : what follows below specifies the additional research that the preliminary work on TWA 800 itself suggests should now be undertaken.

Both the Joint Spectrum Center and NASA have—in different ways (the first in oral statements, the second in written statements)—openly acknowledged the possible incompleteness of their work.

In their report entitled “Investigation of Electromagnetic Field Threat to Fuel Tank Wiring of a Transport Aircraft,” NASA scientists stated their conclusions that the HIRF, or High Intensity Radiated Fields, environment surrounding TWA 800 was not strong enough to have acted as an ignition source.⁸ According to their calculations, the signal strengths listed by the Joint Spectrum Center could have introduced at most 0.1 millijoule of energy into the fuel quantity wires running into the fuel tank, whereas 0.2 millijoules is the level required for ignition.⁹

NASA, however, appended a second supplementary study—entitled “Some Notes on Sparks and Ignition of Fuels”—which called into question the accuracy and applicability of the 0.2 millijoule standard when talking about RF (radio frequency) sources of electrical excitation. Its central argument is summarized in its opening abstract and restated in its conclusion:

There is little to suggest that data on ignition levels from high voltage sparking is particularly applicable to sparking from breaking contacts excited from an RF source.¹⁰

The second NASA report ends by specifying four avenues of future work that are needed in order to determine an accurate RF ignition standard. The report also observes that most of the work so far done on RF ignition appears to have been carried out in Britain, Germany, and other European countries, and worries, “This fact may indicate that there is not a cadre of American investigators with much background in RF ignition problems.”¹¹

Though the NASA report talks about one very specific “unknown” in the region of electromagnetic interference (the correct standard for ignition from an RF source), this open acknowledgment of what is so far “unknown” turns up again and again throughout many other areas of research on electromagnetic interference, whether the particular report is being issued by the FAA,¹² by the Air Force,¹³ by manufacturers of shielding, or by some other sources.¹⁴ To imagine, therefore, that the door to additional research can be crisply closed on this subject seems incompatible with the generally acknowledged inscrutability of electromagnetic interference, as well as the very specifically acknowledged inscrutability of the accurate standard for RF ignition.

In addition to the question about NASA’s research that NASA itself raises, other questions may be relevant to pose. The scientists carrying out the first of the two studies, “Investigation of Electromagnetic Field Threat to Fuel Tank Wiring of a Transport Aircraft,” repeatedly describe their approach as taking “the worst case” so that not all variations of a given scenario have to be tried: given the scores and scores of possibilities that would have to be contemplated in order to assess every possible variation, this “worst case” shortcut seems extremely sensible. But is it the case that the “worst case” instances really represent the worst case? (This is not a rhetorical question: it may well be that the study does in fact stay exclusively with the most negative possibility. But the only way to make the worst-case status of the worst case visible is to set forth multiple cases and to learn which one of them is “the worst.”)

Three ways in which the study may fall short of a “worst case” design will be specified here. According to the Joint Spectrum Center, at the moment that TWA 800 lost its transponder and all other electrical power (8:31:12 PM), forty-five transmitters in the region were capable of producing signals at the accident site with a field strength that was one volt per meter or higher. The moment selected for the study is the moment when all the clocks (and all other electrically driven instruments on TWA 800) stopped; it is an appropriately selected moment to stop all external action as well and see where each transmitter in the region was. But because the Joint Spectrum Center report also indicates the bearing of each transmitter, it can in many cases be determined whether, in the sixty seconds prior to the clock-stopping moment, a given transmitter was closer or further away and therefore whether its field strength was higher or lower.¹⁵ (In some cases, the relative positions can be inferred and in other cases the accident investigation materials provide a direct record: for example, the National Transportation Safety Board made a film animation, available to the public beginning in December 1997, showing the flight paths of TWA 800, the Navy P3, and USAir 217 in the two minutes prior to 8:31:12. A map of the intersecting flight paths was also forwarded by the NTSB to the Joint Spectrum Center and is included in their report.) Despite the fact that the Joint Spectrum Center figures made it possible to calculate field strengths both at 8:31:12 and in the minute prior to the visible onset of the accident, NASA chose to work only with the 8:31:12 figures.

At the clock time of 8:31:12, the highest field strength figure was the transmitter at Brookhaven Laboratory: its emissions on the surface of the passenger plane were 32.6 volts per meter. NASA therefore took this 32.6 volts per meter as the “worst case.” According to NASA’s figures, once this Brookhaven signal passed into the passenger cabin, it was capable of introducing into the wires running into the central fuel tank 0.097 millijoules of energy, a figure which NASA usually rounds off to 0.1 millijoule. This 0.1 millijoule figure—half of the 0.2 millijoules that currently accepted standards require for ignition—was in NASA’s judgment the worst-case electromagnetic insult to TWA 800 from an external source.

But was it? The Navy P3 plane produced a field strength of 23.8 volts per meter on the surface of TWA 800 at the 8:31:12 clock time when the two planes were separated by a distance of 2.93 miles. But fifteen seconds earlier the P3 had come within one mile of TWA 800. (The one-mile figure is uncontroversial: it reappears in statements by the FBI, by the Pentagon, as well as in the visual and verbal record of the NTSB.¹⁶ ) That means that fifteen seconds earlier, the P3 was producing signals that had a field strength of almost seventy volts per meter on the accident plane.¹⁷

As the field strength of the Navy P3 changes, so too does the level of energy it is capable of coupling into the central fuel tank wire. While the field strength varies inversely with the distance (2.93 miles), the power and energy levels vary inversely with the square of the distance (2.93 x 2.93). According to NASA figures, the Navy P3 when at a distance of 2.93 miles was capable of introducing 0.032 millijoules into the wire running into the central fuel tank. That means at a distance of one mile it would introduce 2.93 x 2.93 x .032 millijoules or close to 0.3 millijoules (0.27 millijoules).

The reader will note that this figure—0.27 millijoules—places it above the 0.2 millijoules level required for ignition. (The one-mile distance, it is crucial to state again, is not speculative: it is not arrived at by saying “What if the P3 had passed within a mile of TWA 800?” The P3, according to the NTSB radar maps, as well as verbal statements throughout the investigation made by the NTSB, FBI, and Pentagon, did pass within a mile). Even using the conservative 0.2 millijoules standard (the figure whose accuracy has been challenged by the second NASA study), a figure significantly beyond that 0.2 requirement has been found.

Does this mean that the ignition source for the TWA 800 accident has been found? It could mean that. At the very least it means that a potential ignition source has been found and that the door to future research on electromagnetic interference has swung open.

To determine whether the P3 could have acted as the ignition source, important additional calculations would have to be carried out.¹⁸ It might be useful to answer many nonnumerical questions as well. It is important to recall, for example, that the P3 itself reported many electrical problems, radio problems, and control surface problems when it returned to its base in Brunswick, Maine, that night. Could some or all of the malfunctions been induced by a High Intensity Radiated Field?¹⁹

H[igh] F[requency] 1 failed to couple entire flight

#3 sh[i]p gauge failed intermittently throughout the entire flight

#3 autofeather will not arm

Copilot master ICS box, no U[ltra] H[igh] F[requency] 1 or 2 lights

H[igh] F[requency] amp causes constant transmitter off light

ECA [Electronic Countermeasures Action] # 12 card…causes bearing #2 needle to be off 30 degrees

I[dentification] F[riend] F[oe] transponder bad, no mode C

M[agnetic] A[nomaly] D[etector] R-32 black pen is inop[erative;] fuse checks good

Mode C inop[erative] during entire flight²⁰

#2 powerlever 36 degree switch inop[erative], will not autoshift with powerlevers forward of 36 degrees²¹

Rudder trim has to be turned several turns before it engaged and trimmed the aircraft. Happened several times throughout flight²²

This list constitutes a high number of electrical (or potentially electrical) malfunctions. It is only a partial list of the many problems the P3 pilots reported when they returned to their air base the night TWA 800 fell. In the forty-two days prior to July 17, the crews of this particular P3 reported a total of eight malfunctions: that means that twice as many malfunctions happened on this single night of July 17 as happened in the entire six weeks leading up to that night.

At what point in its flight did these electrical malfunctions begin? ²³ If the P3 first suffered these problems close to the time TWA 800 fell, then both planes may have been the victim of some third transmitter (it is conceivable that a high-powered military transmitter seeking to put the relatively immune P3 in its field of vision inadvertently illuminated both the P3 and TWA 800 at the moment when the two planes crossed paths).²⁴ If instead the Navy P3 suffered its electrical problems only long after TWA 800 fell, it remains a candidate for the ignition source of the TWA 800 explosion. What is clear is that the crew of the P3 themselves should be asked specifically for whatever pertinent information they can supply concerning the crash of TWA 800. So far nothing in the record indicates that this has been done.²⁵

But let us proceed to a second area in which a question can be raised about whether the NASA study successfully achieves a “worst case” design.

The Joint Spectrum Center had presented NASA with a list of forty-five signals whose field strength on the surface of TWA 800 ranged from one volt per meter to 32.6 volts per meter (and, as noticed a moment ago, up to seventy volts per meter fifteen seconds earlier).

NASA then took these figures indicating the strength of the signal on the outside surface of the plane and (applying their new method of numerical computation) calculated what the strength would have been once the signals came in through the windows in the passenger cabin; they then calculated what the strength of the signals would have been once it passed from the passenger cabin onto the wires (running inside the walls and flooring beside the passenger seats) that travel into the central fuel tank.²⁶

But this seems a somewhat circuitous path to the particular wire under investigation (the fuel quantity system indicator wire running into the central fuel tank). Is it the most direct way that High Intensity Radiated Fields could have coupled onto the wire? Since this passage involves attenuation of the signals, is this the path that would indicate the severest impact of the signals?

The answer to these questions may be “yes.” It may well be that this indirect path to the fuel quantity indicator wire does represent the worst case, and that the various physical properties of the passenger cabin mean that it would—despite attenuation—result in the largest figure. But how do we know in advance what the “worst case” is unless several cases are looked at and the one with the worst result chosen?

An alternative way that the HIRFs on the exterior wall of the plane could conceivably have come into direct contact with the fuel quantity indicator system wire is through the wheel well. (The wheel well is the cavity into which the landing gear retracts after takeoff and prior to landing.) The National Transportation Safety Board’s exhaustive study of the interior of TWA 800 had in fact expressed a concern about the uneven levels of shielding on the plane’s wiring. The wire bundle that travels into the central fuel tank at one interval runs through the wheel well where it is unshielded for a distance of ten feet. Because of its location on the underside of the plane, the wheel well is almost immune to lightning strikes, and for this reason the wire was permitted to be unshielded. But though the wheel well is immune to lightning, it is no more immune to radio and radar signals than any other aperture, or port of entry, into the plane.²⁷

In November of 1998, the FAA issued an Airworthiness Directive applicable to all 747 models requiring replacement of “all of the FQIS wiring outside of the fuel tanks and surge tank with shielded wiring.”²⁸ This action will provide protection for the ten feet of formerly unshielded wire running through the wheel well (as well as for hundreds of other feet of FQIS wire running through other sections of the plane²⁹ ). The directive states the purpose of the new requirement:

To prevent electrical transients induced by electromagnetic interference (EMI) or electrical short circuit conditions from causing arcing of the fuel quantity indication system (FQIS) electrical wiring or probes in the fuel tank(s), which could result in ignition of the fuel tank(s).

TWA 800 prompted the new requirement for the shielding of this wheel well wire in Boeing 747s; but TWA 800 was not, of course, itself the beneficiary of the new requirement, and the question remains whether it could have been here—in the wheel well—that signals from various transmitters could have coupled onto the wires.

While the NTSB report indicates that the FQIS wire is vulnerable to the outside world during its ten-foot run through the wheel well, NASA overlooked the wheel well. Its report assumes that external HIRFs could only arrive at the fuel quantity indicator wire by the indirect, two-step process of coming in the windows, before then passing through the interior walls to the wires. It in fact states that HIRFs can only indirectly, not directly, reach this particular wire.³⁰ This is especially puzzling because though NASA does not see the wheel well as vulnerable to the outside world, it does see the wheel well as the place where any electromagnetic signals inside the cabin (whether from HIRFs that have arrived there through the windows or from passenger-carried computers and cell phones) can most adversely affect the wire.³¹

How much energy couples onto the wire is in part determined by the relation between the wavelength of the impinging radiation and the length of the wire, or what is called effective antenna length, and can, as NASA notes, only be determined experimentally rather than computationally since it varies so much with frequency.³² What strength would the Brookhaven signal at the frequency of 2875 MHz (that was 32.6 volts per meter on the outer surface of the plane) have once it directly coupled onto the wheel well wire; what strength would the Riverhead transmitter signal in the 1294.6 MHz range (17.9 volts per meter at the outer surface of the plane) have once it directly coupled onto the wheel well wire? What strength would the forty-three other signals in different frequencies have been? Perhaps the answer is that the levels would be lower than the levels NASA has already found in the two-step path; but it seems worth finding out for sure.

NASA experimentally tested different frequencies (that it assumed to be coming from inside the cabin) and found one very surprising result, a result listed as the third of the three major conclusions to this first study. Though HIRFs could not have acted as the ignition source (conclusion one), and though passenger computers and cell phones could not have acted as the ignition source (conclusion two), low-frequency signals³³ illuminating defective wire could cause discharge (or sparking) events by introducing as little power as 0.17 W (conclusion three). But they determined that this could not explain the fuel tank explosion because passenger cell phones and computers don’t operate in this frequency, and though HIRFs do operate in this frequency (among many other frequencies),

analysis revealed that the whole TWA-800 aircraft could not have coupled more than .015 W of power in this frequency range from the surrounding EM environment at the time of the accident.³⁴

But if the .015 W power level has been arrived at only by the two-step process of indirect illumination by HIRFs (first having it pass through the cabin window, then having it illuminate the wires running through the walls), then it would seem relevant to determine the power level at this frequency by direct illumination in the wheel well.³⁵

A third question about NASA’s “worst case” design involves the multiplicity of signals in the TWA 800 environment. In a complex electromagnetic environment, can the “worst case” be identified by isolating any one solitary emission—whether Brookhaven’s 32.6 volts per meter, or the Navy P3’s 23.8 volts per meter field strength, or the P3’s 69.7 volts per meter field strength at fifteen seconds before the catastrophe manifested itself, or Riverhead Air Force antenna’s 17.9 volts per meter, or any one of the forty-two other emissions so far not enumerated here? One of the most common observations made about electromagnetic interference is that it is hard to reproduce in the laboratory even when scientists are fairly confident that it has taken place in the field; and one of the most common explanations given for this difficulty in replication is that the laboratory often tests one frequency at a time, rather than reproducing the actual situation in the field where multiple frequencies are present and may be interacting.

Multiple signals within a single frequency (the two readings at the 2745 MHz frequency from the two radars at Islip provide a simple instance) can add or subtract from one another depending on the degree of phase alignment of the two signals. The formula for stating the worst-case outcome for signals at the same frequency (in the highly unusual case where the two signals are perfectly aligned) requires that their respective strengths be added together (in the 2745 MHz frequency, the signal strength would be 7.6 + 7.4 or 15 volts per meter); a more usual formula states the average outcome of interaction by squaring each number, adding the squares, then finding its square root (in the 2745 MHz frequency, the revised reading would be 10.6 volts per meter). While signals at the same frequency can amplify, or diminish, one another’s effects, so can signals in adjacent frequency bands, and so, too, can frequencies that occur at harmonic multiples of one another.³⁶ If TWA 800 suffered from electromagnetic interference, it is possible that a single frequency from a single transmitters was the cause. Or it is also possible that a complicated interaction between some or all of the forty-five signals registering higher than one volt per meter was the cause.³⁷

The FAA’s 1997 Flight Standard Information Bulletin about High Intensity Radio Fields³⁸ had warned that a “fast changing R[adio] F[requency] environment” outside a plane can cause power to jump from high-voltage wires to low-voltage wires at some place inside the plane where the two are bundled together. Just such a jump from high- to low-voltage lines inside TWA 800 had been contemplated by the NTSB as a possible avenue along which inappropriate levels of power had been carried into the fuel tank,³⁹ even though the NTSB had not connected that concern with an external radio frequency environment or with the FAA advisory on High Intensity Radiated Fields. Does the Joint Spectrum Center’s list of signals from forty-five fixed and mobile emitters constitute “a fast changing R[adio] F[requency] environment”?⁴⁰

Does the list of forty-five emitters, once supplemented with many other potential emitters omitted from the original study, constitute such a “rapidly changing radio environment”? It is to the subject of the omitted transmitters that I now turn. Of the three stages of work—

• the NTSB compilation of transmitters;
• the Joint Spectrum Center’s computation of the strength of the transmitter signals once they left the site of transmission and traveled to the surface of the plane; and

• the NASA analysis of whether these transmission figures could have served as an ignition source

—it is so far exclusively the third stage of work that has been contemplated here. NASA explicitly states its own recognition of the need for additional work in a second report exclusively devoted to the problem of determining an accurate RF ignition standard. I have attempted to suggest a number of other ways in which NASA might be asked to undertake additional research: the P3’s field strength fifteen seconds prior to the visible onset of the catastrophe appears to create an energy level significantly above the 0.2 millijoule level currently understood to be required for ignition, and calls attention to the fact that the emission levels of transmitters in the two-minute period prior to the accident need to be looked at; the wheel well could be tested as a possible site of direct illumination by HIRFs and compared with the two-stage path NASA has already examined; and the interaction of multiple signals could be tested. Decrease in craft distance, more direct paths of illumination, and the interaction of multiple signals have been introduced here one by one, but all of them need to be studied together.⁴¹

But as we now back up from the third stage of work (NASA) to the second stage (the Joint Spectrum Center), and from the second stage to the first (the NTSB), we will see that the incompleteness of the first stage of work puts all later stages in jeopardy.

Just as NASA openly acknowledges, by its second report, the incompleteness of the work it has so far carried out on RF ignition, so too does the Joint Spectrum Center openly state a crucial caveat about its own report: it acknowledges that its own accuracy is dependent on the accuracy of the list of transmitters provided by the NTSB.⁴² If the NTSB list omits sources, the Joint Spectrum Center’s report omits sources, and in turn NASA’s conclusions understate the hazard.

It will be useful to contemplate briefly the Joint Spectrum Center’s own impressive resources, and then see how those resources can be thwarted by inaccurate information forwarded to it by the prior stage of investigation.

When the National Transportation Safety Board asked the Joint Spectrum Center to give a technical portrait of the electromagnetic envelope surrounding TWA 800 at the moment its catastrophe began, the NTSB was asking the Joint Spectrum Center to carry out a task requiring great virtuosity, but one the Center was well practiced in carrying out. Since the 1960s when it came into being, its central work has been to solve problems that arise from shared use of the electromagnetic spectrum, or what it refers to in its mission statements as “E3” problems, a shorthand for Electromagnetic Environmental Effects. Its facilities in Annapolis are split into two buildings on opposite banks of the Severn River. The headquarters—located beside a nature reserve that also contains the remains of a once-spectacular antenna array used for submarine communication throughout the twentieth century—is jointly staffed by members of the Navy, Air Force, and Army who rotate responsibility for the Joint Spectrum Center’s leadership. Located here too, behind locked doors, is the highly classified library of radio and radar frequencies, the most complete record of transmitters anywhere in the world.

If the Joint Spectrum Center had set out to tell the Safety Board the strength of all antennas and sensors at the site of transmission, the classified library alone would have provided the answers. But they sought to answer a more difficult question (and the only question that mattered). They wanted to determine the strength of the signals not at the site of transmission but at the site of reception—the site of reception being TWA 800.

For this task, the data bank of frequencies and signal strengths located at the Joint Spectrum Center’s headquarters was crucial but insufficient. Across the Severn River near the Naval Academy is the Joint Spectrum Center’s second, much larger building: it contains laboratories and offices for four hundred scientists trained in electrical engineering, computer science, and physics. Technically the civilian organization housed here is a part not of the Joint Spectrum Center (or any other military or governmental body); it is part of the large, civilian, nonprofit Illinois Institute of Technnology Research Institute that has branches in several states. However, this particular branch of IITRI, called IITRI Annapolis, carries out research projects for only a single entity, the Joint Spectrum Center. Its contract with the Joint Spectrum Center began when the Joint Spectrum Center began, in the middle 1960s, and continued uninterrupted throughout the Seventies, Eighties, and Nineties (during most of which time the Joint Spectrum Center was called the Electromagnetic Compatibility Analysis Center). It is, in fact, the longest continually running single contract in the United States government.

In August 1998, the Joint Spectrum Center and its partner, IITRI Annapolis, took on the task of determining the exact field strength of each radio or radar signal in the region of the TWA 800 accident not at the moment it left its land, sea, or airborne antenna but at the moment it arrived at the passenger plane making its way through the summer sky.

The National Transportation Safety Board clearly made an effort to be accurate in the list it forwarded to the Joint Spectrum Center. The list contained revisions in what had earlier been specified as the distances of various craft from the accident plane. The Aegis cruiser USS Normandy had always earlier been described by NTSB, FBI, and Navy officials as 180-200 miles away; its distance was now corrected to 156.3 miles. The Normandy had also been repeatedly described as the ship (other than the Coast Guard cutter Adak) closest to the accident, a description that turned out not to have been accurate. The NTSB’s list now specified two surface ships that had not been included in any previously announced FBI or NTSB listing. The SS Halyburton, an Oliver Perry Class Navy frigate, was located 130 miles east-northeast of TWA 800, and the Navy supply ship USN Seattle was located 43 miles to the west.⁴³

But the list was still starkly incomplete:

Certainly Omitted Craft One: Moving on the water three miles south of TWA 800 was a ship traveling at thirty knots. It is visible on the NTSB radar data. Because it is so close to both TWA 800 and the Navy P3 plane, it has been an object of steady interest throughout the inquiry. Both the FBI and the NTSB have at every moment throughout the investigation certified that this object was indeed there (given the radar data, any other position would be almost impossible); but they have, with almost equal consistency, acknowledged frank ignorance about what it is.⁴⁴ If efforts have been made to ascertain its identity, those efforts have not been described to the public.

The investigation into the accident by former FBI assistant director James Kallstrom entailed, according to his own statements, direct inspection of 371 vessels passing though New York Harbor⁴⁵ and scrutinizing the records of 20,000 vessels that passed under one of three Suffolk County bridges in a three-month period.⁴⁶ Yet another ship—one large enough to show up on radar data, sailing not in New York Harbor or under one of the Suffolk County bridges but out in open ocean waters close to the plane—has been left uninterrogated and unidentified.

The Joint Spectrum Center has provided meticulously calculated figures for signals arriving at TWA 800 from Navy and Coast Guard ships 5 miles, 40 miles, 130 miles, and 156 miles away. The usefulness of those meticulous calculations is seriously compromised if the signals arriving from a ship 3 miles away have been omitted.

The spectrum of possible safety or harm is wide: the ship may have been a fishing boat that carried no high-powered transmitters; or it may have been a pleasure ship carrying no transmitters; or the ship may have been a second Aegis cruiser. (We know from the Joint Spectrum Center calculation that the Normandy—even at a distance of 156.3 miles—produced a field strength of 3.77 volts per meter at the outer surface of TWA 800; and from this we may estimate that an Aegis cruiser 3 miles away would produce a field strength of 196 volts per meter on the accident plane. So, too, we know that at a distance of 156.3 miles, the Normandy was capable of introducing into the passenger cabin .017 millijoules of energy⁴⁷ ; thus we also know that at three miles it would be capable of introducing 45.97 millijoules (this would be considerably above the 0.2 millijoule standard required for ignition).⁴⁸ The classified field strength levels of the antennas on our telemetry ships (we have two on each coast; they are used to track cruise missile tests) may be even higher.⁴⁹ But why, rather than stating the possibilities, do we not have a simple direct identification of the ship as we have for the 371 ships the FBI personally boarded and the 20,000 ships whose papers it inspected?

Certainly Omitted Craft Two, Craft Three, and Craft Four. Three other ships—located respectively two, three, and six miles northwest of TWA 800—also appear on the NTSB radar data but have never been identified, and therefore could not be included in the study of transmitters carried out by the Joint Spectrum Center.⁵⁰ The NTSB forwarded to the Joint Spectrum Center the radar display of planes and ships located within a few miles of the accident plane; but while the nearby planes carried identifying labels on the radar picture, the ships bear only a label indicating their speed (twelve-fifteen knots in two cases, twenty knots in the third). If the Joint Spectrum Center knew the identity of the ships, it would then—drawing on its library—also know the transmitters carried by those ships, and could then go on to calculate the strength of the signals produced by those transmitters at the accident site.⁵¹ But the first step in this sequence is the single step that the otherwise highly competent Joint Spectrum Center cannot carry out: it has no legal authority to inquire into the identity of the ships; that task must be carried out by the legally authorized agency for accident investigation, the NTSB.

The list of ships the NTSB forwarded to the Joint Spectrum Center includes ships as far away as 217 miles, 243 miles, 252 miles, 260, 269, 278, 304, and 347 miles. (None of these ships were incorporated into the Joint Spectrum Center’s study since they are all beyond the radio line of sight.) Such listings, along with the listing of ships in coastal ports, give an aura of completeness, even overcompleteness. But how can a list be complete if no ship within a ten-mile radius of the accident is listed, with the exception of the Coast Guard ship Adak,⁵² whose motions were widely reported by the press at the time of the accident, whose identify has therefore been consistently known to both the public and to accident investigators, and whose transmitter signals were therefore included in the Joint Spectrum Center study?

Possibly Omitted Craft Five: Navy documents (obtained by Freedom of Information and forwarded by this author to the NTSB) ⁵³ indicate that there were two P3s in the Long Island region on the evening of the accident. One is designated as being in the New York area: this is the already long-identified P3 that came close to intersecting TWA 800’s path moments before the fall and is included in the Joint Spectrum Center and NASA studies. The second P3 is designated as being in the W-105 region and is not included in the study.

Does the absence of the second P3 from the Joint Spectrum Center study mean that the NTSB never bothered to inquire into its location? Or does it instead mean that upon inquiry, the NTSB learned that, contrary to the Navy document,⁵⁴ no second P3 was in the W-105 region? The NTSB needs not only to track down answers but to make certain the answers are publicly known. Just as the NTSB’s attention is obligatory, not discretionary, so the public’s attention in the case of the death of fellow citizens is obligatory, not discretionary. Information needs to be given to the public at large so it will understand when it has successfully discharged its own obligations to fellow citizens who have been mysteriously killed or injured.

None of the many craft listed by the NTSB appears to be situated inside the exercise zones W-106 and W-105, portions of which are within ten miles of the crash. Does that mean W-105 and W-106 were empty on the evening TWA 800 fell? Or does it instead mean that the NTSB has included only craft in the civilian air lanes and sea lanes? The place on the map where W-105/ W-106 begins is marked with clear lines, giving the appearance that these regions can be crisply segregated off from the narrow corridors of civilian waters. But electromagnetic signals do not stop traveling through the air at the place on a map where a line is drawn. If there were craft inside W-105 and W-106 they must be included in the study.

Possibly Omitted Crafts Six, Seven, Eight, Nine, Ten, Eleven, Twelve, Thirteen, Fourteen, Fifteen, Sixteen, Seventeen, Eighteen, Nineteen, Twenty, Twenty-One, Twenty-Two, Twenty-three, Twenty-four, Twenty-five, and Twenty-Six: Beginning in August 1999, the NTSB made available to the public its radar data from a geographical area larger than the twelve-by-sixteen mile region shown throughout its week-long December 1997 accident hearings. An independent researcher from the University of Florida and another from the University of Maryland each separately transcribed the data in the band just beyond the region that had earlier been shown and found images of more than twenty ships, some inside W-105 and others moving together from a position outside the warning area into the warning area in the fifteen minutes following the fall of the plane.⁵⁵ The transcribed data also shows two planes south of TWA 800, one flying toward W-105 and the other circling into and out of the warning region.

The NTSB has not itself stated in public whether these findings are accurate. If they are not accurate, the NTSB needs to show its own method of transcription and the pictures that result. If they are accurate, then the NTSB needs to identify the craft and forward them to the Joint Spectrum Center so that it can supplement the work it has already carried out and forward the new figures to NASA. Portions of W-105 and W-106 are only ten miles from the accident: it should go without saying that the use of powerful transmitters in this area could significantly change the picture of the electromagnetic environment surrounding TWA 800.

Incompletely Described Crafts Twenty-Seven and Twenty-Eight: The twenty-seventh and twenty-eighth craft involve imprecision (rather than an omission) but imprecision so large it comes close to being a stark omission. Two Air Force planes—a C-141 and a KC-10—are acknowledged to have been in the area. But neither their distance from, nor bearing in relation to, TWA 800, is specified. The distance is listed as twenty-five miles, but is followed by a note indicating that this is an “assumed distance separation.” How much is being “assumed” in the twenty-five-mile figure? Give or take three miles? Nine miles? Twenty miles? Power levels of radio and radar transmissions fall off at a rate of the square of the distance as one moves away from the object; phrased the other way round, power levels increase at a rate of the square of the distance as one approaches the object. Whether the C-141 is twenty-five miles away or seventeen miles away or seven miles away makes a large difference in the Joint Spectrum Center’s field strength calculations. Equally crucial is the bearing of the two planes which the NTSB simply dismisses as “unknown.” (Bearing lets us deduce how close to the accident plane the other two planes were one minute prior to the crash.)

It is hard to puzzle out why, after securing the help of the Joint Spectrum Center—the one laboratory in the whole country with a technical expertise so comprehensive and so long practiced it could perform the exact calculations needed to see if the plane was vulnerable—the NTSB then decided to throw all precision to the wind by “guesstimating” that the C-141 and the C-10 were—“shall we call it twenty-five miles?”—away from the place where 230 people died.

The following craft, then, need to be identified and added to the Joint Spectrum Center’s otherwise virtuoso study, and added in turn to the research carried out by NASA that builds on the Joint Spectrum Center computations:

• one ship located three miles south of TWA 800 whose existence is certain;

• a second, third, and fourth ship located two to ten miles northwest of TWA 800 whose existence is certain;

• a P3 in the W-105 military area whose existence is indicated in a Navy document but whose existence has not yet been verified by the NTSB;

• a group of more than twenty ships and two planes in, or near, the W-105/W-106 area whose existence is indicated by radar pictures transcribed by two independent researchers from data provided by the NTSB, but whose existence has not yet been verified by the NTSB itself;

• one US Air Force C-141 and one US Air Force C-10 whose distance, bearing, and altitude need to be precisely specified.

If the NTSB has reasons why none of the listed craft need to included in the Joint Spectrum Center and NASA studies, it should state those reasons publicly.⁵⁶

This list is limited to those craft that are, in varying degrees, already “in evidence,” either because they are in the radar maps or a Navy document establishes its existence. Some of our military equipment is, of course, radar-evading; its whereabouts will only be ascertained when the men and women operating in the area are called upon to describe events in the region.⁵⁷ As I have argued from my initial article on TWA 800 in April of 1998, these men and women are—even more than the high-powered radars and transmitters—the eyes and ears of the country.

The reports and documents pertaining to the NTSB’s inquiry into TWA 800 reveals an investigation that is—in the scrupulous care of its analysis of the plane itself, a masterpiece of precision: the documents map soot patterns on every square inch of the plane’s exterior; every wire, every instrument, every air passageway, every circuit breaker, has been scanned centimeter by centimeter and described in clear language. Members of the research teams even figured out the spins and spirals that small pieces of metal and furniture inside the plane went through as the plane fell. But compared to the tour de force internal mapping, the external mapping of the environment is a blur of partially accurate, partially approximate, half-complete, and wholly absent information.

Incomplete in the case of TWA 800, the reconstruction of the external electromagnetic environment has only barely begun in the cases of Swissair 111 and Egypt Air 990. Will we only become persuaded of the need to look at the external environment if a fourth, a fifth, and a sixth plane fall? Shall we spare ourselves the exhausting labor of inquiry and wait for the environment itself to eliminate all doubt? But surely we are required to act while we still stand in the midst of uncertainty, long before events themselves coerce our conviction.

Acquiring information about the external environment is an obligation, not an option, an obligation that should have been perceived as absolute even when there was only a single catastrophe in this geographical region.

Air Controller: TWA 800, Center.

[No Response]

Air Controller: TWA 800, Center.

[No Response]

Air Controller: TWA eight hundred. If you hear Center, ident[ify yourself]

[No Response]

That obligation grew heavier when, twenty-six months after this first catastrophe, the second followed, its earliest signs of peril occurring in the very geography where its sister plane had fallen.

Air Controller: Swissair 111, Boston.

[No response]

Air Controller: Swissair 111. Cleared direct to Bradd.

[No response]

Air Controller: Swissair 111. Swissair 111. Hear Boston Center. Contact Boston one two eight point seven five, one two eight point seven five. If you hear Boston, ident[ify yourself]

[No response]

Fourteen months after the second catastrophe came the third, the plane having crossed into and crashed within the military zone the two earlier planes had been skirting when they flew the Bette route.

Air Controller: EgyptAir 990. New York Center.

[No response]

Air Controller: EgyptAir 990. New York Center.

[No response]

Air Controller: EgyptAir 990. If you copy New York Center, squawk one seven one two and ident[ify yourself]

[No response]

How much time do we have before a fourth plane—taking off from JFK airport and traveling east over the ocean—fails to answer its radio call?

It is a question that deserves further inquiry.