Memories of Flame: The crash of TWA flight 800
Note: this accident was previously featured in episode 26 of the plane crash series on March 3rd, 2018, prior to the series’ arrival on Medium. This article is written without reference to and supersedes the original.
On the 17th of July 1996, TWA flight 800 exploded and crashed off Long Island, New York, killing all 230 people on board in what remains one of America’s deadliest air disasters. The Boeing 747’s spectacular midair breakup, and the terrifying fate of its passengers and crew, captivated the nation in a way that few plane crashes ever have, before or since. Was the flight brought down by a bomb, a terrorist missile strike, or a catastrophic mechanical failure? It seemed that everyone had an opinion — and an agenda. As the FBI and the NTSB pursued different explanations, the chaos and constantly shifting evidence divided the public and sowed conspiracy theories which persist to this day. In the end, the NTSB published one of the most exhaustive reports in its history, outlining in incredible detail exactly how an escalating chain of events led to a catastrophic explosion of the 747’s center wing fuel tank, ripping the plane in half and sending its burning remains into a long, excruciating death spiral toward the Atlantic Ocean. But the findings, as important as they were, seemingly never caught on with the public, as polls showed that half of Americans did not believe the NTSB’s conclusion that the crash was an accident. What follows is not only a retelling of the cause of the infamous accident, but also a chronology of how the NTSB figured it out, and an attempt to explain the lingering public discontent — the scar left on America’s collective psyche by the crash of TWA flight 800.
TWA flight 800 checked almost all the boxes that would make a flight special, in the classical sense: it was a prestigious route from New York to Paris, operated by one of America’s oldest and most storied airlines, using a mighty Boeing 747, the timeless Queen of the Skies. Looking back, it was perhaps a relic of an earlier, more glorious era of aviation which had, by 1996, already ended.
The first generation Boeing 747–100 operating the New York-Paris route on the 17th of July that year was already 25 years old, and had been in service with TWA almost continuously since its manufacture in 1971, except for a one year period during which it was sold to the government of Iran but was never delivered. With over 90,000 flying hours under its belt, the airplane, registered as N93119, was nearing the end of its service life and was probably on track to be retired before the year 2000, replaced by something newer, sleeker, and less interesting.
In command that day was 58-year-old Captain Ralph Kevorkian, who was undergoing a routine line check overseen by 57-year-old Captain/Check Airman Steven Snyder, replacing the position normally held by the First Officer. Rounding out the cockpit crew were 25-year-old trainee Flight Engineer Oliver Krick, who had only worked for TWA for 26 days, and his 63-year-old instructor Richard Campbell Jr., an ex-747 captain who had moved to the flight engineer position after exceeding the retirement age. They would be joined by 212 passengers and a full complement of 14 flight attendants, leaving the massive plane only about half full.
The weather in New York that day was typical of summer in the Northeastern US, with temperatures hovering around 28˚C (82˚F) at John F. Kennedy International Airport as TWA flight 800 prepared for its scheduled 19:00 departure. As the aircraft sat at the gate with its air conditioning running, the pilots oversaw the boarding of passengers and the loading of fuel, replenishing the reserves used up during the plane’s inbound flight from Athens, Greece earlier that afternoon. The trip to Paris was well under the 747’s maximum range, so the crew filled up only the fuel tanks in the wings, leaving the plane’s largest tank — the center wing tank, located in the lower fuselage between the wing roots — entirely empty, except for about 300 pounds (136 kilograms) of unusable fuel sloshing about in the bottom.
As so often seems to happen, the pre-departure preparations didn’t go smoothly. The refueling operator encountered an unexpected problem when an automatic cutoff system, designed to prevent the tanks from being overfilled, triggered erroneously and cut off the flow too early. The refueling operator had to reset the circuit breaker and fuse for the automatic volumetric shutoff, then finish refueling manually.
Meanwhile, efforts to reconcile passengers with their baggage suggested that a bag had been loaded into the cargo hold without an accompanying passenger on board the airplane. As an anti-terrorism measure, any such discrepancy must be corrected by removing the offending piece of luggage, and so baggage handlers opened the hold back up again and pulled it out.
At the same time, the pilots were dealing with a totally unrelated problem: an airport service vehicle had broken down directly behind the airplane, leaving no room to push back from the gate. Their scheduled departure time came and went while ramp personnel searched for a tug which could tow it out of the way. An hour passed, and the passengers were becoming antsy to go, most probably without appreciating the miracle of climate control.
Finally, after a seemingly interminable delay, the broken down vehicle was towed away, and a flight attendant informed the pilot that the “missing” passenger had actually been on board the whole time. The bag was loaded back on board, the hold was closed, and the plane finally pushed back from the gate. At last underway, TWA flight 800 taxied to the runway and took off at 20:19, 79 minutes behind schedule. As the 747 climbed away into the setting sun, those who watched it go could not have imagined that it would never return.
After takeoff, everything proceeded in a routine manner, as the pilots completed standard checklists and air traffic control granted them progressively higher altitude clearances. The plane turned east and began tracking along the coast of Long Island, steadily ascending. In the back of the cockpit, trainee Flight Engineer Krick could be heard making a routine report to the company. “Eight hundred with an off report, ah, plane number one seven one one nine, we’re out at zero zero zero two, and we’re off at zero zero one nine, fuel one nine decimal zero, estimating Charles de Gaulle at zero six two eight…”
Out of the corner of his eye, Captain Kevorkian spotted something odd. “Look at that crazy fuel flow indicator there on number four,” he said. “See that?”
Perhaps the indicator needle on the instrument was swinging back and forth, or otherwise moving erratically — nobody knows for sure. But the problem didn’t attract his attention for long, because instructor Captain Snyder never replied, and the conversation returned to routine configuration changes. And seconds later, air traffic control called them and said, “TWA eight hundred, climb and maintain one five thousand.”
“Climb thrust,” Kevorkian ordered.
“Power’s set,” Flight Engineer Krick replied, advancing the thrust levers. Flight 800 began to rise from 13,000 feet toward 15,000.
Forty-seven seconds passed in silence. And then, at an altitude of 13,800 feet, the plane was rocked by a massive explosion.
The explosion instantly destroyed the wiring to both flight recorders, causing them to stop in midair. Nevertheless, we could speculate that a powerful roar would have filled the cockpit, and perhaps there would have been time for someone to ask, “What was that,” but there would not have been enough time for an answer.
Less than five seconds after the explosion, the 747’s entire nose section, comprising the cockpit, upper deck, and first several rows of main cabin seats, bent downward and ripped away with the deafening screech of rending metal. As a cloud of debris blossomed out behind it, the severed cockpit plunged like a rock toward the shining water far below.
Meanwhile, the rest of the plane, minus the cockpit, immediately pitched up and began to climb. The departure of the nose had made the plane 80,000 pounds lighter and shifted its center of gravity toward the rear, creating an uncontrollable pitch-up moment. With the wings, stabilizers, and engines intact, the decapitated plane hurtled upward, flames whipping across the gaping hole where the forward fuselage used to be, pieces of wreckage, seats, baggage, and passengers spewing out in its wake. Ascending steeply and beset by enormous drag, it began to lose speed, and the left wing started to dip; the plane then turned to the north, arcing across the evening sky as it hurtled toward its dying zenith. Flames streaming from its fuel tanks, the headless 747 finally stalled, turned on its side, and began to descend, accelerating downward into a corkscrew dive. The wing tips tore away, followed by the left wing in its entirety, triggering a massive explosion which could be seen for miles, burning bright like a falling star against the gathering dusk. Spinning around and around in an endless spiral, the remains of the plane continued to disintegrate, plunging in freefall toward the water, until at long last what was left of TWA flight 800 slammed into the dark waters of the Atlantic Ocean, taking with it the lives of all 230 passengers and crew.
Although the entire event from initial explosion to final water impact lasted no more than 54 seconds, the 747’s prolonged and fiery breakup was witnessed by hundreds of people as far away as midtown Manhattan and the coast of Connecticut. Most of them initially did not understand what they were seeing, but a few of them did, including the captain of Eastwind Airlines flight 507, which was flying directly toward TWA flight 800 from the northeast at a height of 15,000 feet. He thought he saw the landing lights of an approaching plane, so he flicked on his own lights to signal his presence, and then the airplane exploded before his very eyes. Within seconds of the blast, the Eastwind captain radioed his observation to air traffic control. “We just saw an explosion out here, Stinger Bee 507,” he reported. “Ah… yes sir, it just blew up in the air, and then we saw two fireballs go down to the water…”
Far below, numerous people witnessed the crash aboard boats sailing off the coast of Long Island, and many of these rushed to the crash site to search for survivors. What they found instead was a scene that would have been more at home in Dante’s Inferno. As far as the eye could see, the ocean’s surface was strewn with burning wreckage, fire and water mingling in the gathering darkness. In the rays of their floodlights these first responders spotted numerous mangled bodies floating amid the debris, but as the hours crawled past, they were forced to conclude that no one had survived.
News of the crash spread with extraordinary rapidity. News stations provided wall-to-wall coverage, which for the first time included widespread use of the internet, driving enormous increases in traffic to the fledgling online versions of the New York Times and CNN. Within 24 hours of the crash, traffic to some of these sites had quadrupled, raising overall internet use in the United States to record levels. But almost as much traffic went to “TWA 800” websites rapidly set up by private individuals — sites which provided information, often of dubious credibility, to a public desperate for any scrap of knowledge about the sensational disaster.
Meanwhile, multiple government agencies immediately launched a sweeping operation to respond to the crash. Foremost among them was the National Transportation Safety Board, or NTSB, which assumed its normal role as the lead agency in the investigation. The NTSB pulled out all the stops, dispatching one of the largest teams in its history to study every aspect of the crash as part of a project which would ultimately expand to include hundreds if not thousands of people.
However, the FBI also deployed a large team of investigators, who had a very different mission: to determine whether or not the crash was a criminal act. At the time, the circumstantial evidence suggested that this was a strong possibility, given that the plane exploded suddenly without a distress call. All kinds of speculation ran wild both on and off the internet, as witnesses described seeing a bright light ascending into the sky before the explosion — an observation which was quickly interpreted as a missile. FBI agents sent to Long Island to investigate the crash were therefore given explicit directions to search for evidence that a missile either did or did not strike TWA flight 800.
By the time the NTSB had its team on the scene, the FBI had taken charge of interviewing witnesses, denying the NTSB access to hundreds of people who claimed to have seen the crash. Despite the investigators’ frustrations, this critical early step in any investigation had to be postponed.
Instead, the NTSB focused on recovering the wreckage from the ocean floor. In a complex multi-stage operation, salvage teams first recovered floating debris and bodies, followed by the more substantial portions of the airplane which lurked below. Although the most significant items, including the two flight recorders, were found within the first few weeks, this effort never truly stopped as long as the investigation was ongoing, and items were still being recovered as late as the year 2000.
One of the NTSB’s first priorities was to search for evidence that an explosive device, such as a bomb or a missile, had detonated on board the plane or just outside it. As wreckage was recovered, they began to reassemble the fuselage, piece by piece, onto a wire frame in order to identify the way in which the fuselage broke up, as well as any areas that may have been penetrated by an explosive device, leaving telltale signs such as high-energy entry/exit holes, hot gas washing, and micro-pitting of the metal.
However, a search for these signs largely turned up empty. Although the reconstructed fuselage did include some conspicuous holes, most of the “missing” material in these areas was actually folded into the surrounding pieces, leaving no obvious gap that could be hiding explosion damage. The remaining areas showed no signs of such damage either, although there were 196 small holes in various locations that required further study. Teaming up with Boeing, the NTSB conducted an experiment in which they fired small pieces of shrapnel at varying speeds toward representative sheets of metal and studied the resulting holes. What they found was that shrapnel traveling at greater than 1,500 feet per second (460 m/s), such as would occur during the detonation of an explosive device, creates a distinctly different type of entry/exit hole than debris moving at speeds below 1,000 feet per second. All but two of the 196 shrapnel holes in the fuselage and fuel tanks of TWA flight 800 showed characteristics of the latter, indicating that they were made by objects traveling too slowly to have come from an explosive device. Furthermore, they were all pointing the wrong way to have come from a missile: every one of the 196 holes had been made by an object originating from inside the plane.
The FBI, meanwhile, began testing pieces of recovered debris for any sign of residue left behind by explosives that might be used in a bomb or missile. Most pieces tested negative, but three gave back a positive result. Two of these were pieces of carpet from different parts of the cabin, and the third was a fragment of a canvas-like material from an unidentified area. The three items were handed over to the NTSB, which confirmed that they contained trace amounts of three different explosive materials. But these items were located in different areas of the plane, none of them showed signs of having been exposed to a blast, and none of the wreckage in between them had been exposed to explosive residue. It was therefore hard to believe that these pieces represented strong evidence that an explosive device had detonated on board.
In order to learn more about where the traces could have come from, the NTSB placed explosive materials on similar pieces of aircraft debris, and exposed other pieces of debris to an actual explosion, then placed them in ocean water and measured how long it took for the residue to dissolve. They found that all the residue should be dissolved within two days underwater. Since it took more than two days before wreckage recovery even began, the residue almost certainly must have been placed on these items after the crash, not before. Investigators theorized that military personnel, some of whom worked with explosives, may have contaminated the items during the recovery process.
Alternatively, if the residue had somehow survived underwater, the items could have been contaminated during a K-9 training exercise conducted aboard the plane in June 1996, during which dogs were trained to find real explosives placed in different parts of the cabin. Officers who participated in the exercise told the NTSB that one of the containers of explosive material had developed a crack and was leaking, potentially explaining the contamination.
Simultaneously, other clues began to point away from sabotage. The cockpit voice recording was largely unremarkable, except for the comment about the “crazy” fuel flow indications — that is, until the very last moments. Upon analyzing the tape in detail, the NTSB found that the last tenth of a second of the tape contained a loud, explosive noise audible only when it was slowed down considerably. This sound could only have been the explosion which brought down the plane. But when they compared the sound to similar noises recorded in the final moments of previous flights destroyed by bombs, such as Pan Am flight 103 and Air India flight 182, they noticed a key difference. The recordings of bomb blasts aboard airplanes captured a sharp sound which rose very quickly to an abrupt crescendo, but the blast heard on TWA flight 800’s CVR rose much more slowly, like a gathering rumble. That suggested that the explosion aboard TWA 800 might not have been caused by a bomb.
Meanwhile, autopsies of the victims were conducted in search of shrapnel that would indicate the detonation of an explosive device in or near the passenger cabin. In most such cases, shards of debris are driven deep into the bodies, and in fact nearly 20 years later just such a fragment would be used to identify the type of missile which brought down Malaysia Airlines flight 17. But in the TWA 800 victims, pathologists could find nothing. None of the victims had been penetrated by high-speed shrapnel, and all died of blunt force trauma. A few who had been seated over the wings seemed to have suffered from burning prior to death, but only superficially.
Despite the early belief that an act of sabotage was the leading theory, all of this evidence strongly suggested that the crash might have been an accident after all. An analysis of events outside the plane supported this interpretation. No terrorist group lodged any credible claim of responsibility, and background checks on the passengers came back clean. Furthermore, an examination of data collected from primary radar facilities, which bounce signals directly off physical objects as opposed to tracking transponder signals, showed no tracks intersecting with TWA flight 800 that could have been a missile. One station appeared to capture something which might have been a track speeding away from TWA 800 seconds after the explosion, but this track appeared out of thin air and disappeared back into it just as quickly, and it never intersected the flight path of the airplane anyway. The fact that it wasn’t recorded by any other radar facility strongly suggested that it was a glitch, and this in fact turned out to be the case: the track was a perfect match for an aircraft cruising at 400 knots ground speed, only in a different location. In fact, the radar signal had simply reflected off a building in between the plane and the receiver, causing the track to appear in the wrong place.
As all of this was taking place, the NTSB’s structures and sequencing teams sought to determine how the plane broke apart, and in what order, in the hope that the answers to these questions would reveal the source of the explosion. By mapping roughly where each piece of debris was recovered, the team revealed that the wreckage could be divided into three adjacent zones, arranged progressively along the airplane’s flight path. The first zone, christened the “red zone,” was closest to the point at which the explosion occurred, and contained debris from the fuselage behind the cockpit but in front of the wings, including two of the three air conditioning packs, several key structural beams, and part of the center wing fuel tank. Most of this debris showed only light sooting, indicating that it was briefly exposed to fire but did not burn.
The second zone, called the yellow zone, was located in the northeast corner of the red zone and contained the entire nose section of the plane, which appeared to have hit the water in one piece. No evidence of fire was found in this area.
Finally, beyond the borders of the red and yellow zones lay the green zone, which contained everything else: the wings, center fuselage section, aft fuselage, and tail. Many items found in this area showed heavy exposure to fire while the plane was still in the air, especially those from the center section and right wing, where the fuel tanks had evidently ignited during the plane’s descent toward the sea, triggering the large explosions seen by witnesses.
By gathering data on the shape of each piece of debris and combining it with data about the speed of the plane and the speed of the wind in the area, investigators were able to create a computer model which could estimate which pieces broke off at which times, given where they ended up. The model showed that everything in the red zone broke off immediately after the explosion, followed by the nose section no more than five seconds later. But for the rest of the wreckage to end up in the green zone, so far from the site of the explosion, it must have continued to fly in a semi-stable manner for as much as 40 seconds before taking on ballistic characteristics (i.e., those of an object free-falling through air). Calculations conducted by Boeing showed that if those portions of the plane found in the green zone had remained in one piece following the initial explosion, the wings would have continued to generate lift, and the reduction in weight combined with the extreme aft center of gravity would have resulted in a severe pitch-up moment. This pitch up would have resulted in an increase in altitude from 13,800 feet up to a height between 15,500 and 16,600 feet before the drag from the fuselage’s blunt forward opening caused sufficient loss of speed to result in a stall. Following this aerodynamic stall, the remains of the airplane descended rapidly and broke apart, breaching the fuel tanks and triggering several explosions before the wreckage eventually struck the water.
Most significantly, however, the simulation revealed that the first noteworthy piece to come off the plane was not a part of a baggage compartment, or a section of fuselage skin, but a structural beam known as spanwise beam #3, which runs from right to left across the interior of the center wing fuel tank. Furthermore, the forward baggage compartments, where a bomb likely would have been located, were found largely intact and unburnt. This evidence suggested that the explosion did not occur in the baggage area, but actually began with some kind of overpressure event in the center wing fuel tank immediately behind it.
The center wing fuel tank is a large, sealed void in between the wings, which consists of a number of interconnected “bays” demarcated by spanwise structural beams. The forward wall of the tank is defined by a major structural member called the front spar, and the rear of the tank by a similar member called the rear spar. Notably, the front spar and spanwise beam #3 were found in the red zone, while the other two spanwise beams and the rear spar were found in the green zone several kilometers further on. Damage to these items showed that this was no coincidence. Placing the items next to each other, it was clear that spanwise beam #3 had been subjected to a massive force which caused it to separate from its top chord, rotate forward about its still-attached bottom chord, and slam directly into the back of the front spar. Indeed, the geometry lined up perfectly.
Following this impact, the front spar separated from the fuselage skin and bent forward around the plane’s two potable water tanks, causing it to fracture. Without the support provided by the front spar, the blast emanating from the center wing tank ripped open the lower fuselage skin, sending cracks snaking in every direction, until they completely surrounded a particular section of skin. This section then gave way, and the blast escaped downward, taking with it most of spanwise beam #3 and the front spar, along with the forward end of the keel beam — the structural member running front-to-back underneath the fuel tank, which gives longitudinal strength to the fuselage. When the keel beam broke in two, the forward section of the plane lost rigidity. Cracks circled all the way around the fuselage until the nose folded down and broke away, as evidenced by multiple tension failures discovered in wreckage from the airplane’s roof just behind the cockpit. This entire process took between three and five seconds.
An exhaustive examination of all the wreckage from this area turned up no signs of pre-existing damage which could have led to a catastrophic failure of any of the structural members involved. Everything had failed due to simple overload, all the way back to the initiating event: the massive force which pushed spanwise beam #3 forward into the front spar. With a bomb all but ruled out, there was only one other thing in the fuel tank which could have caused an overpressure event: the fuel itself.
Proving that the fuel tank simply exploded, without any type of sabotage, would be a tall order — and not only would the public need serious convincing, but so would the investigators themselves, many of whom were initially skeptical that such a thing was even possible (and in the end a few were never convinced at all). But as they dug deeper into the theory, their eyes would be opened to a whole world of disturbing evidence that had never been adequately examined before.
The first question that investigators needed to answer was whether the fuel in the tank was even flammable at the time of the explosion. Contrary to popular belief, Jet A fuel, like most other petrochemical fuels, is not very flammable in liquid form, and it takes considerable effort to ignite it. On the other hand, when mixed with air in the right concentration, Jet A becomes not only highly flammable but positively explosive. The NTSB’s goal, therefore, was to determine the exact temperature and concentration of the fuel/air mixture inside TWA 800’s center wing fuel tank at the precise moment that the plane exploded.
In order to accomplish this goal, the NTSB assembled a team of leading experts in fuel and fuel combustion to gather research into the topic of fuel flammability and apply it to TWA 800. This team found that barely any research had been done in this area, and that most reference information about the flammability characteristics of Jet A fuel were based on a single study from the early 1970s. The team therefore set up its own experiments to determine the specific concentrations and temperatures at which Jet A fuel becomes flammable.
The temperature at which a fuel-air mixture reaches the particular concentration at which it will ignite when exposed to a spark is known as its flash point. The NTSB team acquired fuel samples from the Athens-based supplier which filled the accident airplane’s center wing tank on the day of the crash and found that this fuel had a flash point of 45.5˚C (114˚F). But that didn’t mean that the temperature of the fuel had to have been above 45.5˚C for it to have ignited aboard TWA 800. In fact, the only parameter which determines whether a fuel-air mixture can ignite is its concentration, and this depends not only on temperature, but also pressure. After a series of experiments, the NTSB found that at an altitude of 13,800 feet above sea level, the fuel could actually ignite at temperatures as low as 35.8˚C (96.4˚F). Although increased altitude means a lower concentration of oxygen in the air and generally makes things harder to burn, the effect on the fuel’s minimum ignition temperature was the opposite, because the lower atmospheric pressure allowed the fuel to mix with the air more readily, causing it to reach the required concentration at a lower temperature.
From circumstantial evidence alone, it seemed likely that the fuel in TWA 800’s center wing tank, or CWT, could have been in the flammable range. With only 136 kilograms (or 190 liters) of unreachable fuel left in the 45,400-liter fuel tank, relatively little energy would have been required to heat the fuel enough to cause it to mix readily with the surrounding air. Furthermore, because of the warm temperatures and lengthy ground delays, flight 800 sat on the ground with its air conditioning packs running for two and a half hours before it took off. The air conditioning packs were located directly beneath the CWT, coming as close as 5 centimeters from the bottom of the tank, and there was no insulation between them whatsoever. These air conditioning packs take hot air fed directly from the engines and cool it down for use in the passenger cabin, a process which requires getting rid of excess heat. This heat is vented directly into the air conditioning pack bay, where it makes contact with the bottom skin of the CWT. Investigators therefore hypothesized that the air conditioning packs could have heated the fuel enough to create a flammable fuel-air mixture in TWA 800’s center wing tank which persisted until the time of the accident.
With this in mind, the NTSB staged an impressive experiment to recreate the conditions inside TWA 800’s CWT. They acquired fuel from the same supplier in Athens, flew it to JFK aboard a Boeing 747, left exactly 190 liters of it in the CWT, ran the air conditioning packs for two and a half hours, then took off within one minute of TWA 800’s actual departure time, on almost the same day of the year, using the same aircraft weight and configuration. The airplane then climbed along a trajectory which stayed within 1,000 feet, 20 knots, and one minute of TWA 800’s actual flight profile, while sensors monitored temperatures and fuel concentrations in the CWT. By the time the plane reached 13,800 feet, the temperatures in various parts of the CWT ranged from 38.3 to 51.7˚C, above the minimum ignition temperature of 36.4˚C, and the fuel-air ratio was 0.054, above the minimum ignition concentration of 0.038. The experiment therefore left no doubt that the fuel in TWA 800’s center wing tank was flammable at the time of the accident.
To further prove the theory, the NTSB contracted a group of explosion dynamics experts, who constructed a scale model of a Boeing 747 CWT and ignited fuel inside it 72 times, a mammoth experiment which took two years to complete, in order to determine how flame propagates inside the tank. In every test which resembled the conditions aboard TWA 800, the fuel ignited and the flame front propagated throughout the tank. The experiments also showed that the “bays” within the tank tended to ignite progressively, causing multiple pressure spikes with a directional component.
Simultaneously, Boeing calculated the force required to cause the failure of spanwise beam #3, the event which initiated the breakup of the airplane. This value was then compared against the forces generated in the scale model test. After running the calculations, the NTSB was able to prove that the force applied to the beam during a fuel-air explosion inside the CWT was sufficient to cause the observed damage.
Just to make sure, the NTSB conducted one last ambitious test: they triggered an actual CWT explosion and detonated a bomb aboard a decommissioned 747 in order to record the sounds produced on the CVR by these different explosions. The results confirmed everything known so far: the bomb blast resulted in a sound which rose and dissipated quickly, while the fuel-air explosion produced a sound which built up more slowly, just like the one recorded on the CVR of TWA 800.
At last, everything was coming together. This series of experiments had shown that the fuel-air mixture in the tank could be ignited, that such an ignition would cause a powerful explosion, that such an explosion would produce the sound heard on the CVR, and that this explosion was capable of initiating the breakup of the airplane, beginning with spanwise beam #3. But by this point, more than two years had passed since the accident, and the FBI was still investigating sabotage as the leading theory. Only after presenting all of the data gathered so far did the NTSB investigators manage to convince the FBI that the explosion was not caused by a bomb or a missile, but by some spark which ignited the residual fuel in the center wing fuel tank.
The other major question that they needed to answer was where that spark came from. The NTSB had in fact begun searching for an ignition source as soon as it began to suspect that the CWT exploded, but this area of inquiry would prove to be the most difficult part of the investigation.
The basic problem is that Federal Aviation Administration (FAA) regulations assume that airplane fuel tanks are always flammable. Consequently, fuel tanks by law must be designed to exclude any ignition source that could ignite this flammable mixture. Could some ignition source have found its way into the tank regardless?
The NTSB didn’t need any specific knowledge of ignition sources aboard TWA 800 to know that the answer was yes. In fact, supposedly explosion-proof fuel tanks had exploded before — not just once, but many times.
One of the most common ignition source in such cases is lightning. Most famously, in 1963 Pan Am flight 214, a Boeing 707, exploded and crashed near Elkton, Maryland after a lightning bolt penetrated one of its fuel tanks via an unknown entry path. All 81 passengers and crew were killed. Thirteen years later, in 1976, lightning struck a Royal Iranian Air Force Boeing 747 as it was on approach to Madrid, causing the left wing fuel tank to explode. All 17 people on board were killed in the ensuing crash. Once again, the exact entry path was not determined, although a faulty fuel pump or fuel quantity indicator was suspected.
There have also been cases which did not involve lightning. In 1989, Pablo Escobar’s powerful Medellín drug cartel planted a bomb in the passenger cabin of Avianca flight 203, causing the Boeing 727 to explode over Colombia, killing all 107 people on board and three on the ground. Investigators found that the bomb was not powerful enough by itself to have destroyed the plane, but structural failure occurred when shrapnel from the bomb penetrated and ignited a flammable fuel-air mixture in the center wing fuel tank.
And perhaps most noteworthy of all was the case of Philippine Airlines flight 143. On the 11th of May 1990, this relatively new Boeing 737–300 was pushing back from the gate at Manila’s Ninoy Aquino International Airport when the center wing fuel tank violently exploded, killing eight passengers and seriously injuring another 30. The NTSB was heavily involved in the investigation, which found that a flammable fuel-air mixture inside the mostly empty CWT might have been ignited by electrical arcing inside of a faulty float switch — a device that measures the amount of fuel in a tank by floating on the surface of the liquid — which was improperly powered by a damaged wire.
These were some of the deadliest of at least 15 fuel tank explosion accidents and incidents uncovered by the NTSB during a search of archival records. Although these explosions had a variety of ignition sources, most of these sources could be ruled out right away in the case of TWA flight 800. The NTSB had already found no evidence of bomb blast damage near the CWT, or indeed in any other part of the airplane; furthermore, the crash occurred in clear skies with no nearby storms, and no witnesses reported seeing lightning at the time of the accident, so a lightning strike could also be excluded.
The NTSB ultimately considered at least fourteen ignition scenarios, ranging from electromagnetic interference to static electricity to cell phone signals to a meteorite strike. Most of these were ruled out due to lack of evidence, insufficient energy to trigger ignition, or both. Investigators were able to exclude the possibility that the wall of the tank, or the fuel itself, became hot enough to cause auto-ignition or hot-surface ignition, because such temperatures could not be reached without causing easily detectable damage to the walls of the CWT. A meteorite strike was ruled out because the probability of a meteorite striking an airplane was infinitesimally small, and besides, there was no evidence of an entry point. An uncontained engine or air conditioner failure could also have launched debris into the tank, and a faulty fuel pump could have sparked the explosion if both of its ignition protection features also failed, but there was no evidence that any of these things occurred either. Eliminating all of these options basically left electrical sources as the only remaining possibility.
Calculations showed that 0.25 millijoules of energy are required to ignite Jet A fuel vapors at sea level and that between 0.5 and 500 millijoules are required at 13,800 feet, depending on the temperature of the fuel. A few electrical ignition scenarios were found which could produce this much energy. However, regardless of its initial source, there was really only one realistic way for this energy to have entered the fuel tank: that is, through the fuel quantity indicating system. Because aircraft fuel tanks are required by FAA regulations to be devoid of any ignition sources, the fuel quantity indicating system, or FQIS, is the only system which has any electrical wiring running inside the tank. However, the wiring for this system does not carry more than 0.02 millijoules of energy, less than 10% of that required to ignite the fuel-air mixture. That meant that the energy must have merely used the FQIS wiring as a conduit after originating somewhere else. The question, then, was where.
One by one, the NTSB began eliminating possible sources. Electromagnetic interference from radar and radio sources at ground stations and aboard other planes could not have generated more than 0.1 mJ of energy aboard the 747, and less than 0.01% of this energy could have been induced into the FQIS wiring. A NASA study found that even in a worst case scenario, no electromagnetic source on board the plane could have induced more than 0.125 mJ of energy into the wiring either. Even less energy could be induced by personal electronic devices, as the NTSB found when they applied the strongest commercially available transmitter directly to a sample FQIS wire and were unable to transfer enough energy to create a spark. Static electricity was even more of a wash: a clamp inside the CWT, which was judged to be the most vulnerable object in the tank, was found not to accumulate enough static electricity to discharge more than 0.0095 mJ of energy into the fuel.
The one scenario which the NTSB could envision which would allow sufficient energy to enter the tank was a short circuit between an FQIS wire and a wire which carried more energy. This led the NTSB to examine the general state of the wiring on the accident aircraft, and more specifically the places where FQIS wires ran in close proximity to wires which carried power sufficient to ignite Jet A fuel.
Although FAA regulations require wiring for certain critical systems to be routed away from other wires to prevent short circuits, the NTSB found that these rules did not explicitly mention the fuel quantity indicating system, and while some manufacturers separated it anyway, Boeing indeed had not provided any such protection to the FQIS on the 747. Investigators found that on the accident airplane and other 747s, FQIS wiring and high-power wiring for the cabin lighting system were frequently run along common raceways and even bundled together, along with wires from numerous other systems, including but not limited to the number four engine fuel flow indicating system and the captain’s channel of the cockpit voice recorder.
A number of items of circumstantial evidence strongly suggested that there was an anomaly involving all of these systems shortly before the explosion. About a minute before the blast, Captain Kevorkian pointed out some kind of anomalous indication on the number four fuel flow gauge. Then, a few tenths of a second before the explosion, the captain’s channel of the cockpit voice recorder captured two brief gaps in the electrical background noise, leaving only a distinct tone with a frequency of 400 hertz, indicating some kind of unusual electrical event. And lastly, the CWT fuel quantity gauge was found in the wreckage displaying a fuel weight of 640 pounds — more than twice what was actually in the tank, and outside the instrument’s error specifications. Furthermore, this error must have appeared after the plane became airborne, since the fuel logs left by the refueling operator showed the correct amount. Testing carried out by the NTSB would later show that the application of high power to the FQIS wiring would cause the fuel quantity indication to increase at a rate of about 1,000 pounds per second. A reading of 640 pounds would therefore be consistent with a power surge in the FQIS wiring about 0.34 seconds before either the explosion or the activation of the circuit breaker, whichever came first.
As the saying goes, where there’s smoke, there’s fire — but for the NTSB, a higher standard of evidence is needed. Despite all of these tantalizing clues, this ignition scenario could only be proven with the discovery of hard, physical evidence of arcing between the 350-Volt cabin lighting system and the FQIS. But with the plane shattered into a million pieces on the bottom of the sea, finding that evidence ultimately proved impossible, as not all of the FQIS wiring could be found.
And yet, a thorough examination of the available wiring did turn up additional circumstantial clues. Evidence of electrical arcing between two wires was found in a raceway which also contained wires from the cabin lighting system and the FQIS, but the recovered FQIS wiring from this raceway was undamaged, and the rest was missing. Records revealed that this same area had been subject to several repairs, one of which was to fix water damage. One or more of these repairs had also left the raceway covered in sharp metal shavings, some of which were found on a piece of wreckage less than 5 centimeters from where missing FQIS wiring would have run. In total, at least ten repairs were found in close proximity to FQIS wiring, any of which could have led to damage, and some of which were not in the airplane’s maintenance logs. Finally, in one area, chronic drainage problems in the forward galley had caused water to drip onto a raceway containing FQIS and cabin lighting wires, creating potential for a short circuit via water, which would not necessarily leave behind physical evidence. Indeed, any of these locations could have been the epicenter of a short circuit which led to a power surge in the FQIS wiring, but where exactly it happened will never be known with certainty.
Besides these specific instances, inspections of the recovered wiring from all systems showed that its condition was generally poor. Insulation was cracked and chafed; metal shavings were common; and wires and raceways were covered in stains caused by water and other unidentified fluids. Numerous wires, including FQIS wires, had been spliced or repaired incorrectly. All around, the wires were a mess, with the conductive cores themselves exposed in countless locations.
An inspection of 25 other airplanes from multiple manufacturers found that such conditions were widespread through the nation’s commercial fleet. Of these 25 airplanes, only one — a brand new 737 — did not have sharp metal shavings scattered near electrical wires. In many cases, these shavings had sliced open the insulation and exposed the conductive cores of various wires. Numerous other problems were also found, from chafed insulation to cracked O-rings to wire bundles which had adhered into a solid, indivisible mass. In some inspected 747s, wire routing was not in accordance with manufacturer diagrams and wire bundles which were supposed to be segregated for safety reasons were run together. And perhaps most terrifying of all, NTSB investigators found evidence that five of the 25 airplanes had experienced on-board electrical fires which self-extinguished without ever being detected.
Given the abysmal state of the wiring on nearly every in-service aircraft with nearly every major airline, the problem was clearly much greater than just the accident airplane or TWA. Part of the problem was that most wiring was not required to be replaced until it failed in service, nor was it required to be regularly inspected, except incidentally when inspecting the general area through which it was routed. Because many portions of an airplane’s wiring are not directly visible, these areas were simply not inspected.
Standardization was also lacking. TWA didn’t have standardized procedures for protecting nearby wiring while performing maintenance, leaving it to individual mechanics to judge whether it was necessary to cover or move the wiring. Boeing guidance was equally unclear, and both Boeing and TWA wiring maps differed significantly both from each other and from the way the wiring was actually routed on most individual airplanes.
The cumulative effect of this widespread dysfunction was that short circuits and other wiring-related malfunctions had become extremely common throughout the fleet, with such incidents occurring on a daily basis, many of them unnoticed by anyone. Any one of these faults could become a link in the chain of events leading to a future accident (and indeed, as an editor’s note, some of them did).
Still, even after all this research, one final question remained: once the energy entered the FQIS wiring, what was its exit point? If every part of the system was working correctly, a complete circuit should have been present and the energy never should have left the wire and entered the fuel.
The possibility of damage to the portion of the FQIS wiring inside the tank could not be excluded, but most of this wiring was never found, so there was no proof that it could have sparked. Some more promising leads were found on the fuel quantity probes themselves. On one probe from the CWT, a compensator was found severely burned, but it was not possible to tell whether this damage happened before or after the explosion. But the probes from the CWT also showed another type of damage: a blackish buildup of silver sulfide surrounding the point where the wiring connected to the probe. The NTSB found that this contaminant had been deposited by a chemical reaction between sulfur impurities in jet fuel and the silver plating around the core of the FQIS wire, which was partially exposed by design where it entered the probe. Because silver sulfide is semi-conductive, an arcing event could have occurred between an exposed wire conductor and a nearby silver sulfide deposit, resulting in ignition of the fuel vapors. However, it was not possible to conclusively prove this theory with the available physical evidence.
Nevertheless, there were plenty of signs that silver sulfide deposits on fuel quantity indicators were causing problems throughout the fleet. Similar deposits were noted in post-accident inspections of other aircraft, including a Tower Air Boeing 747 in 1998. This particular airplane had developed problems with its automatic volumetric shutoff system, which kept cutting off fuel flow prematurely during refueling — the exact same problem which occurred on TWA flight 800 just before its departure. These problems were found to have been caused by buildups of silver sulfide in areas where the FQIS wiring inside the fuel tanks had been damaged.
Opportunities for airlines to have discovered the damage were limited. Inspections of the fuel tank interior were only required when the whole plane was inspected and refurbished at regular D-checks, which occurred approximately once every five years. In TWA’s case, detection was further complicated by the absence of specific instructions for mechanics to follow when inspecting the FQIS wiring and probes, including such basic items as what damage looks like, where it can be found, and how to look for it.
The NTSB noted that Boeing had been aware of this issue since at least 1991, when it stopped using silver-plated wires in the FQIS on newly manufactured airplanes. However, the company clearly was not aware of the potential severity of the issue, since it made no effort to retrofit planes which were already in service.
The NTSB now had a credible sequence of events which could explain the crash from start to finish. First, the prolonged use of the air conditioning packs while on the ground caused the residual fuel in TWA 800’s center wing tank to heat up until it reached a flammable vapor concentration. Then, as the plane climbed through 13,800 feet, an electrical arc probably occurred between the cabin lighting system and the fuel quantity indicating system. Before the circuit breaker could activate, this power surge traveled down the wire into the center wing tank, where it probably jumped from an exposed or damaged conductor into a deposit of silver sulfide, creating a spark which ignited the fuel vapors and destroyed the airplane.
The occurrence of such an accident held grave implications for the safety of every air traveler. The investigation had revealed a range of possible faults, many of them present on a large percentage of all airliners, which could evade the safety precautions enshrined in longstanding fuel tank design principles. That such a sequence of events could and would happen again if nothing was done could hardly be doubted.
In order to convince regulators of the seriousness of the issue, the NTSB set out to quantify the danger posed to worldwide air traffic. Their calculations revealed that, on average, 30% of all flights in the air at any given moment contained flammable vapors in their CWTs, and 7% contained flammable vapors in their wing tanks as well. Data showed that this risk was especially high in hot climates and in the months of May, June, and July. And while regulations already assumed that fuel tanks were flammable, the FAA’s principle of precluding ignition sources had proven dangerously flawed. In effect, this meant that 30% of all flights carried the equivalent of an unexploded bomb beneath the passenger cabin, just waiting for a spark that could ignite disaster.
But when the NTSB asked Boeing to analyze the risk of a fuel tank explosion, the company initially refused to take the problem seriously. In response to an NTSB request, Boeing produced a fault tree analysis which they claimed would prove the risk of a fuel tank explosion was extremely low, somewhere on the order of one in 12 billion per flight hour. But the fault tree analysis diagram came with an attached table containing probabilities assigned to each risk factor which differed from those in the diagram. When the NTSB ran these numbers instead, they arrived at a probability of one in 68,500, not one in 12 billion. When asked to review the analysis and correct this discrepancy, Boeing refused to do so, stating that this “[would not] help identify new areas to inspect or help identify the cause of the accident.” Instead, the NTSB submitted Boeing’s fault tree for review by NASA, which replied that the analysis “cannot stand up to peer review and should not be viewed as realistic.” When writing up this section of their final report, NTSB investigators would only just stop short of accusing Boeing of trying to deceive them.
Boeing was hardly alone in its dismissal of the NTSB’s hard-won findings. By the time this picture of events began to crystallize in late 1998 and early 1999, the American public at large had already latched on to the belief that TWA flight 800 had been brought down by a missile, fired either deliberately by terrorists, or accidentally by the US Navy. Worse still, a widely held conspiracy theory alleged that the NTSB was actively working with shadowy government elements to cover up this massacre of 230 innocent civilians, although the motive for such a vast coverup was unclear. Nevertheless, the extent to which these theories had spread, even within the aviation industry, threatened to derail the NTSB’s efforts to prevent future fuel tank explosions. After all, how could they effectively lobby for change if nobody believed them?
Generally speaking, the foundations of the so-called missile theory lay with the statements of witnesses who claimed they saw a missile hit the plane — those same witnesses to whom the FBI had refused to grant access during the early stages of the investigation. It was not until April 1998 that the FBI handed over the documents they had compiled based on witness interviews in the days after the crash.
But when the NTSB finally got hold of them, the files proved to be a disaster all of their own. The FBI agents didn’t transcribe interviewees’ exact words, and the interviewees were not given the chance to review the FBI’s summaries of their statements. Many of these summaries were deeply flawed. Some of them were internally inconsistent, diverged from the agents’ handwritten notes during the interview, or combined the statements of multiple witnesses without differentiating who said what. Even worse, many of the summaries showed signs of interviewer bias. In fact, one FBI agent interviewed by the NTSB revealed that when the interviews were conducted, the FBI already suspected a missile strike to be the cause of the crash, and was only looking for information that was relevant to the missile theory. In one case, an interviewee stated that they saw something which looked like a “flare” or a “shooting star,” only for the agent to describe this object as “the missile” in their summary of the testimony. Agents were even given suggested interview questions which seemed to be designed for witnesses who had seen a known missile strike, including such gems as “How long did the missile fly,” “What did the terrain around the launch site look like,” and “Where was the sun in relation to the aircraft and the missile launch point?”
The damage inflicted on the resulting testimony by such questions was probably incalculable. Research has shown that witnesses who believe their interviewer is knowledgeable about the event are more likely to give inaccurate information, and in this specific case, the belief that the FBI already knew of a missile being fired could have caused witnesses to describe their observations as a missile, even if they would not have done so otherwise. Furthermore, many of the witnesses had seen news reports about the crash before being interviewed by the FBI, and some of them even told the agents that they decided they saw a missile only after seeing these reports.
Nevertheless, after gathering what data they could from these problematic summaries, the NTSB found that nearly every witness statement correlated well with the known facts of the case. Of 736 witnesses, 599 saw a descending fireball, consistent with the plane in the final stages of its breakup. Another 258 witnesses reported seeing a streak of light in the sky before the explosion, half of whom said it was moving laterally. Only 38 reported that this streak ascended vertically or near vertically, and only seven said that the streak originated from the horizon. Nevertheless, these obvious outliers dominated the public conversation surrounding the crash, so much so that many people believe to this day that most witnesses saw an ascending streak which looked like a missile.
In fact, the NTSB determined that the witnesses who saw a streak of light were most likely observing the crippled fuselage of the 747 climbing toward 16,000 feet following the initial explosion. There were a number of factors which added weight to this theory and discounted the missile theory. For one, from some positions on Long Island the plane would have been moving directly toward the observer, making this ascent appear near-vertical. Secondly, all of the witnesses who claimed to see the streak of light rising from the horizon were located near buildings and trees and probably could not have actually seen the horizon. Those who could see the horizon, including people who were on the beach or in boats, universally reported that the streak originated well above the horizon. Third, local police calculated the lines of sight of witnesses who thought they saw a streak of light or flare-like object, and found that essentially all of them were looking toward the green zone, where the crippled remains of the plane arced over and dived toward the water. And finally, many witnesses who thought they saw the start of the accident sequence stated that they were first alerted by the sound of an explosion, which, given their distance from the airplane, would have taken an average of 40 seconds to reach them, meaning that they could only have witnessed the end of the crash sequence, not the beginning.
Despite these observations, there remain to this day dozens of witnesses who will swear on their mother’s ashes that they saw a missile hit the plane — even if their initial witness statements given to the FBI didn’t describe anything which looked like a missile at all. Research has shown that human memory and perception are inaccurate from the start, and that as the elapsed time since the event increases, these memories become even less accurate, while at the same time the witness becomes more and more confident about what they remember. All the while, a witness’s memory is constantly reshaped by additional information about the event, gleaned from news reports, statements by other witnesses, and even completely unrelated events which the brain decides are relevant. The final result is that many witnesses who saw the crash of TWA flight 800 have come to believe they saw a missile, even if they actually got the idea much later. But if you point this out to them, their increased confidence causes them to become defensive, and you will likely hear a response along the lines of “I know what I saw.” This is not a personality fault — these witnesses fully believe that they saw a missile, and if you or I were in their position, we would also believe that any argument otherwise is a personal affront and probably an attempt to whitewash our testimony.
Just to put these theories to rest, the NTSB conducted one final test with an unusual objective: to determine what, if anything, witnesses would actually have seen if a missile were fired at TWA flight 800. In 2000, at the very end of the investigation, the NTSB arranged a series of missile tests at an Air Force base in Florida, during which several missiles would be launched under dusk conditions similar to those at the time of the accident. Observers were placed at intervals from two to 14 nautical miles away from the launch site, were told where to look, and were given radios on which to listen to the countdown before each launch. Although nine countdowns were initiated, only three culminated in a missile actually being fired. While the three actual missile launches were easily detected by all observers, in four cases someone reported seeing a missile launch after one of the fake countdowns, when there was nothing in the sky. But the most important discovery was that the streak of light from a missile launch is only visible for the first seven or eight seconds after launch, during its initial engine burn. After this, the engine turns off and the missile coasts to its target, during which time it is invisible to observers at any range.
Therefore, if witnesses had actually observed a missile striking TWA flight 800, they should have seen a streak of light moving upwards from the horizon, followed by several seconds of nothing, and then an explosion in a totally different location. The actual impact of the missile into the airplane would not have been visible. Needless to say, not a single one of the initial witness statements followed this pattern, nor do most of the statements by witnesses who later came to believe they saw a missile. Tellingly, their statements track closely with the popular image of what a missile hitting a plane should look like, not what it actually does look like.
Unfortunately, none of this has stopped conspiracy theories from pervading mainstream discourse about TWA flight 800. In 1998, shortly after the NTSB announced that an accidental fuel tank explosion was the leading theory about the cause of the crash, a poll showed that only about 50% of Americans believed them. At the same time, allegations of a coverup brought in impressive cash flows to those who made them, and continued to do so for more than a decade after the disaster. A 2004 novel about a fictional couple who accidentally videotaped a missile hitting TWA 800 and are forced to flee the country to preserve the evidence spent 11 weeks in the number one spot on the New York Times bestseller list. Similarly, a 2013 “documentary” by Epix TV, which alleged a coverup of a missile strike against TWA 800, was widely viewed at the time and is still talked about nearly a decade later, despite the fact that it contained nothing more than tired reiterations of long-debunked claims regarding witness statements and spurious radar data. Not explained in the film, of course, is why anyone would have felt it was necessary to hide the truth in the first place.
The documentary’s self-proclaimed credibility relied on statements by six former members of the investigation team who disagree with the NTSB’s conclusions. That sounds impressive, until one recalls that the investigation involved hundreds of people, most of whom possessed narrow expertise and were not qualified, or even physically able, to assess the evidence as a whole.
These kinds of dubious claims of credibility are widespread among TWA 800 truthers. For example, in November 1996, a former reporter claimed he had access to a French intelligence communication reporting that TWA 800 was shot down by a US Navy missile. His claims were widely reported — until it turned out that this “intelligence communiqué” was actually an email written by a retired pilot which had been circulating on the internet for weeks. Similarly, a fringe theory that flight 800 was struck by a meteorite relies on an analysis of the internal breakup sequence conducted not by a structural engineer, but by an amateur geologist. And a book which holds that electromagnetic interference from a nearby US Navy P-3 Orion ignited the fuel was written not by a physicist, but by a professor of English.
Ultimately, most of the conspiracy theories rely on one of two things: an extremely focused, but highly flawed rebuttal of a single element of the NTSB’s conclusions; or a general statement to the effect that an accidental fuel tank explosion “just isn’t possible.” One of the most popular TWA 800 conspiracy theorists, the late William Donaldson, was famous for claiming the latter: “In the history of aviation,” he said, “there has never been an in-flight explosion in any Boeing airliner of a Jet-A kerosene fuel vapor/air mixture in any tank, caused by mechanical failure.” This statement is so full of qualifiers that it amounts to a tautology. There is actually no meaningful difference between an in-flight and on-ground fuel tank explosion, other than timing, nor is there any real difference in flammability between Jet A fuel and other common types, such as Jet A-1. Therefore, a careful reading of the claim reveals that it is constructed in such a way as to deliberately exclude the explosion aboard Philippine Airlines flight 143 on arbitrary grounds.
Donaldson’s comments perfectly exemplify the yawning ignorance which underlies most TWA 800 conspiracy theories. This ignorance lies in the relative inability and/or unwillingness of the average person to fully explore and understand how and why the NTSB came to its conclusions. The final report on the accident goes to great lengths to individually address and rebut every potential source of doubt, reasonable or otherwise, but at 341 pages from cover to cover, reading it is a mammoth task which most of the people arguing about TWA 800 in internet comment sections probably have not attempted. Only by reading the report can one gain a true appreciation for the depth and breadth of the NTSB investigation, which was the largest and most expensive in the agency’s history. Dozens upon dozens of experiments involving the leading experts in numerous fields, combined with careful analysis by hundreds of people and backed by a painstaking salvage operation, culminated in a conclusion which should be unimpeachable. Only the most neurotic skeptics among us can reach the final page still convinced that everything contained within is a smoke screen and that they somehow know better.
Fortunately for those of us who fly on airplanes, the NTSB did eventually manage to convince the one group which mattered most: the Federal Aviation Administration. The FAA had been unmoved by past warnings about fuel tank safety, as the NTSB did not hesitate to point out that all of its recommendations stemming from the Philippine Airlines accident were rejected. But with the loss of TWA flight 800, the problem could not be ignored any longer. Initially, the FAA pursued a policy of cracking down on potential ignition sources, even as the NTSB argued that they should abandon their previous philosophy altogether and search for ways to make fuel tanks less flammable. It would take another serious accident before the FAA finally agreed that allowing airliners to fly around with explosive vapors in their fuel tanks was a recipe for disaster.
That accident took place on the 3rd of March 2001, as Thai Airways flight 114 prepared for departure from Bangkok, Thailand. The Boeing 737–400 was sitting at the gate prior to passenger boarding when it exploded without warning, destroying the aircraft and killing a flight attendant. The investigation into the accident progressed in an eerily familiar fashion. Despite initial suspicions that a bomb had exploded on board, no evidence of an incendiary device was found, and the damage instead pointed toward an explosion of the center wing fuel tank. Indeed, the weather was hot and the air conditioning had been running while very little fuel remained in the CWT, creating a flammable fuel-air mixture. Then, as the plane sat at the gate, someone erroneously turned on the fuel pump in the CWT, even though there was no usable fuel inside. The fuel pump had earlier ingested several shards of metal debris, which now began to scrape around and around against the sides of the dry-running pump, until they finally generated a spark which ignited the surrounding fuel-air mixture.
The Thai Airways accident highlighted the inadequacy of trying to predict every possible means by which a spark might enter the fuel tank, and made it clear that rendering fuel tanks inert was the only viable solution. Fortunately, despite the FAA’s initial belief that inerting systems would be too expensive, the cost had come down sufficiently by the mid-2000s for the FAA to change its mind. In 2005, the FAA announced its intention to mandate inerting systems, which pump nitrogen into the fuel tanks to reduce their flammability, on board every new airliner and on any existing airliner built since 1991. The final rule was issued in 2008, and every applicable airliner in the United States — which by now is virtually all of them — had a nitrogen inerting system installed by 2018.
At the same time, the FAA launched a program intended to investigate wiring problems aboard American airplanes and suggest solutions that could reduce the rate of electrical issues throughout the fleet. This program eventually led to the incorporation of wiring-related procedures into the FAA’s special inspection requirements for aging airplanes, along with the adoption of new and more specific guidelines regarding how and how often airlines should inspect aircraft wiring.
Over the course of these two separate initiatives, the FAA issued more than 150 Airworthiness Directives mandating changes to the design of a large number of airplanes in order to improve the safety of their fuel tanks, eliminate potential ignition sources, ensure the isolation of FQIS wiring, and reduce the overall rate of electrical problems. In terms of the sheer number of Airworthiness Directives issued, this made TWA flight 800 the most consequential aviation accident in US history.
Thanks to this fundamental shift in how the aviation industry views fuel tank safety, a similar accident is unlikely to happen again. But that triumph cannot erase the horror of TWA 800’s final moments, her passengers clinging to an airplane that had lost its cockpit and yet refused to crash, climbing higher and higher in a gross extension of their suffering. The things that they saw and felt populate our darkest nightmares, and yet we cannot help but imagine, for we as a society are drawn to such moments of incomprehensible terror like moths to a flame. In some sense it is that very terror which has granted TWA flight 800 its enduring legacy — certainly it would be hard to imagine such status in our collective consciousness being granted to a mere landing accident. And it is perhaps understandable that we struggle to ascribe an event so utterly horrible to the mere banality of fate, a sequence of mundane events that could have happened anywhere and at any time. No, we find it much more comfortable to believe that humanity is the only force capable of imagining an act of such malice, closing our minds to the knowledge that the unthinking universe could just as easily conjure those 54 terrible seconds of existential agony. Believing that that agony was the product of a human mind allows us to indulge our fantasy that someone is in control, saving us from the disturbing thought that perhaps we, too, are merely passengers aboard a pilotless airplane hurtling toward an uncertain zenith.
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