The New York Review of Books

On the evening of July 17, 1996, TWA 800 fell into the ocean seven miles from the Long Island town of East Moriches. The plane had taken off from New York’s JFK Airport and had been bound for Paris, France. All 230 people on board died. The inquiry into the crash, the most expensive and (in its attention to the plane’s internal systems) the most rigorous inquiry in aviation history, has lasted for four years. A final hearing by the National Transportation Safety Board has been taking place on August 22 and 23, 2000, as this issue of The New York Review goes to press; neither the hearing nor the report that will follow it is expected (according to advance press reports) to “pinpoint” the cause of the crash. The full written report will become available to the public in several months.¹

During the first year and a half of the inquiry, investigators from the National Transportation Safety Board and from the FBI concentrated on three matters: the possibility of a mechanical cause, the possibility of a bomb, and the possibility of a missile. In November of 1997, the FBI formally announced its conclusion that neither a bomb nor a missile had caused the accident (at this point, the FBI withdrew from the case). In December of 1997, the Safety Board—which had painstrakingly reconstructed most of the plane and scrutinized all of its internal systems—held a week-long public meeting reviewing the extensive, but inconclusive, evidence it had accumulated.

Investigators had long known that the plane’s central fuel tank exploded, but had at first been uncertain whether that explosion occurred early or late in the sequence of events that brought the plane down. By the time that the December 1997 public meeting took place, the Safety Board had long since concluded that the central fuel tank explosion was an early event in the catastrophe. What still remained was to find the source of the ignition, the cause of the explosion.

Between December of 1997 and August of 2000, the Safety Board continued its search for the ignition source. Included in its inquiry, and emphasized in the August hearings, was the possibility of a short-circuit or some other problem in the plane’s 150 miles of aging wiring. Also included in the inquiry was the possibility of an external ignition source, electromagnetic interference from one, or more than one, of the many military and civilian ships and planes that had been in the vicinity of TWA 800 and that, along with powerful civilian and military transmitters on land, might have produced an adverse electromagnetic environment. This second line of inquiry—electromagnetic interference from a source external to the plane’s own wiring (internal and external sources of ignition are not mutually exclusive:damaged wiring inside a plane can increase its vulnerability to external transmissions)—is the subject of the article that follows.

1.

In the past two years, the National Transportation Safety Board has taken steps to assess the severity of the electromagnetic environment that surrounded TWA 800 on the evening it fell. In July of 1998, the Safety Board promised to enlist the technical expertise of the Joint Spectrum Center, the agency inside the Department of Defense whose laboratories are designed to sort out problems in the electromagnetic spectrum, particularly as those problems affect military craft. The NTSB also promised to call upon the services of the National Aeronautics and Space Administration (NASA), some of whose scientists work directly on problems of electromagnetic interference affecting civilian planes, as well as space shuttles and other craft.²

By August of 1998, the Joint Spectrum Center had begun its work and in January of 1999 it delivered to the NTSB its completed study of the ground, sea, and air transmitters that, according to the NTSB, were known to have been in the TWA 800 environment.³ The $45,000 study designates the signal frequency of each fixed and mobile transmitter and computes the electric field strength each signal would have had at the accident site itself. The Joint Spectrum Center’s report was then forwarded by the Safety Board to NASA so that its scientists could determine whether the electrical field strength at the accident site (as calculated by the Joint Spectrum Center) was strong enough to have provided an ignition source for the explosion suffered by TWA 800. NASA’s assessment was expected to be completed by December 1999, but the complex study required fifteen months rather than the hoped-for twelve.⁴ In March of 2000 NASA forwarded to the NTSB a report concluding that the signal stengths specified in the Joint Spectrum Center study were not strong enough to have caused the central fuel tank explosion.⁵

Two aspects of the work so far accomplished need to be looked at: first, the impressive technical strengths of the Joint Spectrum Center and NASAstudies; second, the incompleteness of the studies, the result of the omission from the analysis of certain ships and planes in the area. The Joint Spectrum Center, though headed by officers from the Navy, Air Force, and Army, does not itself have the legal authority to conduct an inquiry into the military craft in the area of the accident. The National Transportation Safety Board does have that legal authority, and the Joint Spectrum Center must rely on the Safety Board to carry out a full reconstruction of the possible external sources of electromagnetic interference and to provide it with a complete list of those sources. The Joint Spectrum Center openly states that its report is only as accurate and as comprehensive as the Safety Board’s list of military craft in the area is accurate and comprehensive. Since NASA’s research, in turn, is based on the figures arrived at by the Joint Spectrum Center, NASA’s conclusions also depend for their validity on the accuracy of the list the NTSB originally provided to the Joint Spectrum Center.

While major steps have been taken to ascertain the role that electromagnetic interference might have played in the fall of TWA 800 (steps whose strengths and weaknesses will be looked at in detail in a later part of this article), it is important to recall that during the time the Joint Spectrum Center and NASA studies were being made, two other drastic events took place in the same geographical region: the fall of Swissair 111 on September 2, 1998, and the fall of EgyptAir 990 on October 31, 1999. When each of the three accidents is looked at in isolation, each has features that suggest that electromagnetic interference is a possible cause—a possible cause that, like all other possible causes, should be carefully scrutinized.

The three accidents viewed together, however, greatly increase the need to assess with precision the possible role of electromagnetic interference: the occurrence of three accidents in a single area increases the chance that something in the external environment is acting as a contributing factor. Studies by the Joint Spectrum Center and by NASA need to be undertaken not only in the case of TWA 800 (where ships and other equipment that could have caused electromagnetnic interference were unfortunately omitted from the study and should now be added) but also in the cases of Swissair 111 and EgyptAir 990. Carrying out such studies will require that the National Transportation Safety Board first undertake a full reconstruction of the military and civilian craft in the area surrounding each plane. Without a comprehensive picture of all transmitters in the vicinity, no precise analysis of the radio and radar environments can be made.

This essay is a request to the NTSB that such inquiries be started as soon as possible.

2.

Like TWA 800, Swissair 111 is believed to have suffered an electrical catastrophe.⁶ In the case of Swissair 111 as in the case of TWA 800, the originating event remains mysterious: TWA 800’s catastrophe involved the wiring in the central fuel tank and Swissair 111’s catastrophe involved the wiring in the entertainment system located near the cockpit, but in neither case do investigators believe they have yet found the originating cause.⁷

A third feature shared by the two accidents is location, and a fourth is timing. Each year in the United States planes take off more than 8.25 million times; in two years and two months (the time period that separates the TWA and Swissair accidents) the figure is close to 18 million.⁸ Two of those 18 million departures led to a mysterious electrical catastrophe. The two flights that suffered the catastrophe could have originated from two different airports anywhere in the country,⁹ or, for that matter, anywhere in the world. But as it happens, both planes took off from a single airport, New York’s JFK. The two flights could have taken off on any two days of the week and at any two minutes of the day.¹⁰ But as it happens, both took off on a Wednesday at 8:19 PM.¹¹

The literature on electromagnetic interference is full of stories about unwanted electrical upsets that recur in the same space at the same time: one company, for example, found that its computers crashed every Friday at 3:00 PM; the cause turned out to be a piece of mowing equipment that was turned on at 3:00 PM each Friday during the summer. ¹² Electromagnetic interference often does, of course, happen only a single time; but a one-time-only event often remains an unsolved mystery. Frequently unsolved, too, are problems caused by electromagnetic interference that recur irregularly (one day at 3:00 PM, seventeen days later at 9:00 AM, four hundred days later at 7:15 AM) in widely separate locations. When, in contrast, the event recurs at an exact time and place, it may become clear that—as in the case of the computer and the mowing machine—the problem is arising not from some problem inside the affected piece of equipment but from something outside—something on a regular enough schedule that its responsibility can eventually be tracked down.

Both planes started out on a route that took them east along the southern coast of Long Island. TWA 800 began to fall at 8:31 PM, twelve minutes into the flight. Swissair 111 flew for an hour longer than did TWA 800; it crashed off the coast of Nova Scotia at 9:31 PM Eastern Daylight Time. (See map.)

Map

If both planes crossed paths with some fatal electromagnetic event in their environment that was operating¹³ on an almost identical schedule on the two evenings, it would seem that Swissair 111 should have begun to have trouble twelve minutes into the flight (the point when TWA 800’s data recorder, transponder, and data box ceased operating). In fact, something close to this seems to have taken place.

Reports about Swissair 111 have left the public with the incorrect impression that the plane managed to make its way, uneventfully, east along Long Island and north along the New England coast before suddenly beginning to encounter trouble when it was sixty miles from Halifax. The record of the difficulty, as widely reported in the press, begins at 9:14 PM, when Swissair 111’s pilot requests permission to make an unscheduled landing at Boston; the air controller in Moncton, Canada, reminds him that he is much closer to the Halifax airport than to Boston, and asks him if he would prefer to land at Halifax. At the moment of the 9:14 call, the cockpit has smoke in it and—as the data recorder would later reveal to Canadian investigators—ten minutes later the computers on board suddenly begin receiving false information. Over the next ninety seconds, the autopilot disconnects; the data grow more and more anomalous; soon the plane’s electrical systems fail altogether.¹⁴