FACT CHECKING: Popular Mechanics

Writing for Popular Mechanics, reporter Joe Pappalardo wrote “3 Reasons to Doubt the TWA Flight 800 Conspiracy Theory,” a critique of the contents of the documentary, “TWA Flight 800.” Pappalardo’s article can be seen here: http://bit.ly/1cpLSDI. Our rebuttal corrects the mischaracterizations, inaccuracies and misleading statements in the article.

3 Reasons to Doubt the TWA Flight 800 Conspiracy Theory

It took seven years for authorities to produce the most detailed aviation accident investigation in history.

–Inaccurate. It did not take seven years. The FBI suspended its investigation less than two years after the crash, and the NTSB finalized their report four years after the crash. Also, the reporter characterizes the TWA Flight 800 aviation accident investigation as “the most detailed…in history,” yet many NTSB groups that generated factual reports based on their findings were specifically told not to generate analysis reports, which are fundamental tools for determining what happened. This, by the way, was unprecedented in NTSB investigation history. Also, not a single eyewitness out of 670 was ever allowed to testify at any NTSB hearing, which speaks not only to the level of detail missing from the investigation, but also to the fact that the specific details missing from the investigation were mainly those that contradicted the official theory. The significant investigative oversights and failures in this crash investigation are not limited to these two examples.

–The aforementioned explains lead NTSB investigator Hank Hughes’s “we weren’t finished” comment in the “TWA Flight 800” documentary.Duringthe latter part of the four-year investigation, government investigators focused on trying to prove the official theory—with no success. Meanwhile, they avoided looking deeper and without bias into what the forensic evidence actually indicated.

So how many people would it take to manufacture a fake report to cover up a plot?

–Misleading. Irrelevant. No one accuses the NTSB of faking their final report. The charges made against the NTSB and the FBI in “TWA Flight 800” are that evidence was altered, changed, or removed from the investigation and that neither agency seriously looked into the possibility that a proximity-fused missile caused the crash. Instead of addressing these issues, including looking for evidence of various types of missiles other than just shoulder-fired missiles, the NTSB and FBI limited the scope of their investigation to the extent of hampering it and, equally egregious, prevented any of the 670 eyewitnesses from testifying at any hearing on the crash investigation. They also misled the public and their own investigators (virtually none of whom had ever investigated a shoot-down) on what evidence a missile engagement would produce.

–Within two weeks of the crash, after interviewing more than 500 people, FBI agents assigned to determine what the eyewitnesses saw concluded that there was a “high probability” that a missile was involved.

–Not long after this, a two-pronged effort to discredit the missile scenario began. First and without interviewing a single eyewitness, the CIA created a video animation shown to the world saying that the eyewitnesses did NOT see a missile. This video falsely claimed that the aircraft climbed sharply after it exploded and “looked like a missile” but wasn’t one. Radar tracking refutes this sharp climb. Also, according to internal CIA emails we received during production (some of which we show in our documentary), the CIA knew that the radar tracking and black box data provided by the NTSB invalidated their animation. Secondly, the FBI provided the NTSB with “test plates” damaged by shoulder-fired missiles, which explode on contact with their targets. These test plates were presented to the NTSB and the public as proof that the FBI had exhaustively explored the possibility of a missile downing TWA Flight 800. This was deceptive however, because the FBI had only tested for damage signatures created by shoulder-fired missiles and not others, such as proximity fused missiles. Proximity fused missiles explode at a significant distance away from their targets. Damage signatures consistent with a proximity fused missile detonation were found in the TWA wreckage. They include high energy “spike tooth” fractures,inward penetrating holes, and explosive residues throughout the airframe, both interior and exterior. All of this evidence was ignored and/or dismissed as not consistent with a shoulder-fired missile. It is however consistent with a proximity-fused missile.

–Important note: the word “proximity-fused” does not exist in the NTSB final report.

The official investigation into the explosion of TWA Flight 800 in 1996, which killed 230, concluded that a fuel tank had ignited from within, but never determined what sparked the explosion. (Dozens of airplanes have suffered similar events, and the safety regulations governing fuel tanks changed in 2008.)

Misleading, Inaccurate. The in-flight phase of air travel is the safest, and since the introduction of the very safe and high flash point Jet-A fuel in 1965 there has never been an in-flight fuel-air explosion from a mechanical or electrical problem on any commercial airplane. Also, the official investigation did not “conclude[d]” that the “fuel tank had ignited from within,” but only stated it as a probable cause because no ignition source for the explosion was ever found.

But now, all these years later, a new documentary, TWA Flight 800, claims that a missile or bomb took down the plane—and the U.S. government has been covering it up.

–Inaccurate.No claims of a bomb causing the crash are presented in the “TWA Flight 800” documentary. The film does present evidence consistent with a detonation occurring outside of and at a significant distance away from the jetliner.

“It was either a terrorist attack that they wanted to ignore, or an accident as a result of a military operation that went wrong,” Hank Hughes, a former National Transportation Safety Board investigator and driving force behind the film, told ABC News.

What would you have to believe to accept the idea of a 17-year-old sprawling government cover-up?

–Disingenuous. Misleading. No claims of a “17-year old sprawling government cover-up” have been made in “TWA Flight 800.” That said, Hank Hughes, who oversaw the complete reconstruction of the aircraft’s interior, along with five other former investigators who handled the wreckage, do discuss serious wrongdoing on the parts of the FBI and NTSB leadership as well as several investigators working on behalf of the leadership who changed and altered evidence. Beyond this documented evidence tampering during the investigation, Hughes says that the leadership overlooked important pieces of evidence that refute the officially stated probable cause of the crash.

We look back at the original NTSB report to see what it says, and who would have had to lie about forensic tests or doctored evidence. Here’s a refresher on what the report says, and why the original, simpler explanation is still the most likely.

–Misleading. This statement implies someone “had to lie” about forensic tests.In fact, no one deliberately lied about forensic tests.In “TWA Flight 800,” the producers show the FBI agent in charge of deciding what wreckage should be swabbed for explosives saying that the Egis explosives detection machine the FBI was using recorded “multiple” explosives hits. This agent incorrectly believed that the Egis machine provided frequent false positives. Interviews with the inventor of the Egis explosive detection machine and a supervisory agent at the FBI’s Washington laboratory at the time of the crash confirm that the Egis machine rarely, if ever, gives false positives.

–The fact that the FBI itself reported multiple explosives hits inside and outside the airplane begs this question to the reporter: How can a fuel-air explosion in the center wing tank account for the existence of explosives—PETN and RDX—on the wreckage? It is impossible.

–Also problematic and documented in our film was the misinterpretation of the forensic results. Metallurgists and forensic scientists correctly showed that the evidence was inconsistent with a bomb or a shoulder-launched missile. Some of these metallurgists and scientists were misled into believing that the lack of shoulder-fired missile damage meant a lack of any type of missile damage. These scientists didn’t lie. Most had never investigated a shoot-down before and were misled about what the damage patterns from certain missile types look like. The NTSB never ruled out a proximity-fused missile, since that type of missile damage was not considered at all, according to their final report. The word “proximity-fused” does not appear anywhere in the NTSB final report.

–The Popular Mechanics reporter is inaccurate about “the original, simpler explanation” being “still the most likely.” The original explanations were that either an electrical short in a fuel tank pump or static electricity was responsible. The NTSB ultimately dismissed both of these explanations because the careful design of the tanks precluded such occurrences. The NTSB ultimately settled on a short circuit outside the tank causing electrical energy to enter the tank through wires connected to fuel quantity probes. However, the odds of a missile strike are actually much greater than this and therefore a missile strike is actually more likely.

– The Popular Mechanics reporter is also inaccurate because the final theory, that a short circuit outside the tank transferred high energy into the tank through a fuel quantity probe, is virtually impossible. This is because on one end of the line going to the probe, surge protection prevents electrical energy from entering the tank. On the other end, there is a significant air gap between the electrodes that prevent even 3,000 volts from creating a spark. The only way energy could be introduced would be if there were significant deposits built up on these electrodes. However, when many of these parts were recovered, none of the probes showed any significant deposits. That said, even if the probes did have deposits on them—which, again, they did not–the high voltage from a 120-volt line would have had to jump across a damaged probe line, a very unlikely occurrence. Even so, in an overabundance of caution, Boeing engineers protected the lines within a varnish-impregnated nylon sheath. This is why the NTSB was never able to reproduce the alleged energy transfer in real world conditions.

Blast Holes

Investigators reconstructed and analyzed virtually the entire structure of the stricken airliner. The work revealed 196 blast holes in the airplane’s structure. So how did the investigators figure that an internal gas tank explosion caused this damage, instead of a missile or bomb?

Incomplete, Inaccurate, Misleading. What the reporter omitted from his statement here is that many of those holes were directed intothe fuselage from the outside. This indicates a high-velocity explosive event occurring outside the airplane. It is physically impossible for the internal “gas tank explosion” to have caused this damage.

The NTSB’s metallurgists requested that Boeing conduct the tests. (and Boeing had no motive to reach the conclusion that a defect in its own equipment, rather than an act of violence, caused the blast). The engineers created test plates and fired fragments at them at high and low velocities. An antiaircraft missile warhead detonates close to its target, spraying shrapnel at high speeds into the aircraft to destroy it. A bomb made with high-energy explosives would also hurl metal, this time from the inside of the airplane outward and at higher velocities than an inadvertent gas tank detonation.

–Misleading: a “look here, not there” tactic. The reporter is stating as proof the same misleading information that fooled some of the NTSB investigators. Note the reporter’s description of the warhead that “detonates close to its target”. He doesn’t specify how close, yet the distance away from the target is extremely important when determining how fast projectiles will be moving at time of impact and whether or not unique signatures such as pockmarks or melted metal would exist in the wreckage.

These tests indicated that high-speed fragments leave particular signs behind, like deformations on the edges and melted parts of the walls of the hole. High-speed impacts leave little surface deformation. In the TWA 800 tests, all but two of the 196 holes exhibited signs of low-velocity penetration, and the remaining two holes showed signs of both. One of these mystery holes—just 3/16-inch diameter—was examined in the Safety Board’s Materials Lab. “No evidence of melted and resolidified metal was noted on any portion of the hole wall,” the report states.

–Misleading, Inaccurate, Incomplete: After setting the reader up to equate missile damage with melted metal, the reporter’s quotation “No evidence of melted…metal” gives the false impression that the holes on the TWA Flight 800 wreckage could not have been from a missile.

–The extreme forces of air resistance on small projectiles exiting a missile a distance away from a target significantly reduces the speed of these projectiles. So even “low velocity holes,” are consistent with a proximity-fused missile. What’s very important is the inward moving trajectory of the projectiles. This was not highlighted in the NTSB final report on the crash; the many holes and fractures consistent with being caused by projectiles originating from outside are very significant.

–Regarding the two holes with high velocity characteristics mentioned above, all readers are urged to carefully review the official report, “TWA Flight 800 Analysis of Small Holes”. What the Popular Mechanics reporter does not reveal is that the NTSB investigator could not achieve high enough velocities to reproduce on test plates the holes found on TWA Flight 800 wreckage, evenwhen firing test projectiles out of a gun. This means that whatever created the two holes on the TWA Flight 800 wreckage was created by something hitting it at a very high velocity—a much higher velocity than the NTSB investigator was able to achieve during testing with a gun, a much higher velocity than the alleged low velocity fuel-air explosion in the center wing tank and a much higher velocity than that at which the aircraft hit the water.

All the holes near the wing, where the fuel tank that exploded was located, were low-velocity impacts. About 95 percent of the airplane was reconstructed, and the missing parts were too small to hide bomb or missile damage.

–Inaccurate and misleading. Proximity-fused missiles do generate low velocity holes and impacts. Also, the reporter fails to mention spike tooth fractures found throughout the tank, which according to the NTSB, are created by “high energy event[s]”. These documented damage patterns are clear evidence of a high-energy event such as a missile warhead detonating at a significant distance from the aircraft (which is what proximity-fused missiles are designed to do)—not from a low-velocity fuel-air explosion.

To fake these lab results would require a cadre of engineers at Boeing, as well as the NTSB to be in on the conspiracy or be willing to sit quietly as their tests were rigged. Either way, there is a slew of outside voices involved with the tests that could contradict the government’s story.

–Inaccurate, Misleading, Disingenuous. No one in the documentary, which was available to all reporters, has suggested that tests were rigged. The facts were presented, but no analyses of many of these facts were done. The confirmed spike tooth fractures, inward penetrating holes, and explosive deposits were found all over the aircraft. The problem was in the analysis, which as this very article illustrates, was severely flawed and in some key areas, simply not done.

Radar

The east coast of the United States is covered by plenty of radar. The area where TWA 800 went down was in the range of three long-range radar sites, each with a 200 nautical mile radius, as well as five airports and one radar operated by helicopter manufacturer Sikorsky in Shelton, Conn. The others used direct returns. NTSB investigators also used radar data from the U.S. Air Force’s 84th Radar Evaluation Squadron.

There are two kinds of radar returns, primary and secondary. Primary returns mean the radar waves are reflected off the aircraft. Secondary means the signal came from the transponders in the aircraft. The one in Connecticut tracked only the doomed airliner’s transponder signals; all the others were primary returns.

–Inaccurate. The nearby FAA sites used to track the aircraft (at JFK Airport, McArthur Islip Airport, and in White Plains, NY) recorded both primary and secondary returns.

“The Safety Board’s examination of all the available radar data revealed no sequence of primary or secondary radar returns that intersected TWA Flight 800’s position at any time, nor did it reveal any radar returns consistent with a missile or any other projectile travelling toward the airplane,” the report says.

–Misleading. The fact that radar did not pick up missiles heading toward the plane gives readers the misimpression that this proves there weren’t missiles. In 2000, the NTSB conducted a “Missile Visibility Study” where several missiles were fired off the Florida panhandle with eyewitnesses present. While the eyewitnesses clearly saw the missiles, the radar did not pick up any of them—untilthey exploded. The exploded missile parts, highly reflective on radar, were picked up.

–FAA radar tracked these exploded missile parts traveling in a direction consistent with the initial momentum of the missile body and the forces from the missile self-destructing.

A lot of radar means a lot of people sitting in front of screens. The data is all recorded, at each location. Hiding a military warship (deployment records indicate there were none around that night) or a missile track would mean somehow co-opting or coercing every radar operator on duty that night—a daunting task, especially if it was done to cover up an inadvertent military shoot down or unexpected terrorist attack.

–Misleading, irrelevant. There would be no reason to hide a missile track that, based on NTSB missile test firings, would not even exist in the first place. No radar operator hid the location of a fast-moving ship. Such a ship was clearly labeled on NTSB radar plots almost directly below the jetliner, but off by about 45 degrees. Its position was consistent with the launch point of an object that eyewitnesses saw rise off the ocean surface. The FBI identified 371 ships and boats, but this one, the closest to TWA Flight 800, was never identified.

To be fair, many conspiracy theorists have used the existing radar data to back up their own ideas of what brought the airplane down—especially the behavior of some boats and radar anomalies from one of the radar sites that registered objects in the area moving at high speeds, then vanishing. (These were judged to be phantom returns from building reflections.)

–Misleading. While certain radar returns were properly dismissed as being anomalies, the closest ship on radar was not. NTSB radar plots and the NTSB identified it as being consistent with a ship. However, this ship is not mentioned in the documentary “TWA Flight 800” for a reason: it is circumstantial evidence. This documentary presents the hard facts, such as the high-velocity detonation recorded on radar on a trajectory consistent with a fast-moving object that exploded in the vicinity of TWA Flight 800, and the chemical and metallurgic evidence consistent with this external detonation.

None of these radar returns show anything in the air intersecting the path of the airliner, or any vessel behaving in an overtly suspicious way. (See pages 89–94 in the original report.)

–Misleading. Again, the author reports that nothing intersected TWA Flight 800’s path, but as the NTSB established when they conducted their own tests, FAA radar did not record missiles when they were fired, but did record their detonation debris. The author leaves out what actually was recorded on radar: evidence consistent with a detonating missile warhead on a trajectory consistent with a fast-moving object seen by many eyewitnesses, some of whom saw it converge with TWA Flight 800. This radar evidence is not only consistent with the eyewitness accounts, but also with the NTSB’s own missile tests where missile debris was recorded by radar after the missiles self-destructed.

–In the documentary ‘TWA Flight 800’ we highlight evidence that is consistent with the NTSB-determined radar signature of a missile—a missile eyewitnesses saw heading south-bound and then exploding. An analysis of the directed south-bound detonation of this missile by multiple FAA radar sites is presented, but the author completely ignores this evidence, which is clearly described in the documentary and in a petition to re-open the TWA Flight 800 investigation that the investigators in the documentary submitted to the NTSB and made readily available to reporters days before this Popular Mechanics article was written.

Fuel Tanks

As scary as a missile or bomb attack might be, the idea that the fuel tank exploded on its own can be considered even scarier. The biggest leap for investigators back in 1996 was to prove that a fire in the central wing tank (CWT) could have caused an explosion that brought down the airplane.

–Comment: It certainly was a leap because Boeing specifically designed the tanks with the assumption that flammable vapors would always be present. The flash point of Jet-A fuel was well known to Boeing engineers and the scientific community well before the crash of TWA Flight 800.To date, NTSB investigators have not been able to make that leap and prove, using real-world conditions, that an explosion in the center wing fuel tank brought down the plane.

First, those investigating the tanks had to rule out that the explosion started inside that tank, as opposed to a missile or bomb shrapnel piercing it from outside. There is no physical evidence of a bomb blast—no perforations of the fuselage, the fuel tank, or the bodies of the victims.

–Inaccurate. While there was no evidence of a bomb blast, there was physical evidence of an exterior ordnance explosion.The fuselage was penetrated from objects originating outside the aircraft, and the evidence indicates that these objects were from a missile detonating a significant distance away from the airframe.Inward penetrating holes and high energy fractures created by inward moving objects were found throughout the fuselage and aircraft structures, and explosives residue was found throughout the wreckage—both interior and exterior. Those investigating the tanks were trying very hard to show that the fuel tank explosion did bring down the plane—with no conclusive success—while ignoring hard evidence of exploding ordnance outside the aircraft.

Fragments of a missile warhead would not reach the fuel tank…

–Inaccurate. If a manufacturer of missile warheads cannot design any capable of accelerating fragments through relatively thin aircraft aluminum sheets and reach the fuel tanks of airplanes, that manufacturer would quickly go out of business.

and a joint NTSB and British Defense Evaluation and Research Agency investigation found there was no evidence of an explosive charge nested inside the tank by a saboteur. (Such a charge would produce hot gas damage and pockmarks that were not found.)

–Misleading. Here again, the author is dismissing the obvious, which the producers of the film have also dismissed. While the evidence does not support a detonation of a bomb or missile warhead close to any aircraft structures, it does support an external detonation a significant distance away from the aircraft, from a proximity-fused missile.

At the time, there was very little engineering work done regarding fuel tank flammability. The NTSB investigation spawned a team of experts dedicated to studying the issue, which within aviation circles was more heated than the conspiracy chatter: In the aftermath of the crash, any fix that investigators suggested could lead to regulations that cost millions to implement.

–Misleading. The aviation community knew very well that Jet-A vapors were flammable at specific temperatures well before TWA Flight 800 crashed. And knowing this, Boeing engineers designed their tanks with the assumption that the vapors were always flammable. That’s why there haven’t ever been any in-flight tank explosions resulting from internal causes.

The Boeing engineers’ design principle was to prevent any energy from entering the tank to ignite these vapors. To do this, extra protection to fuel gauge wiring in the form of a nylon sheath together with proper surge protection was employed. While only 120 volts was available to short into these wires, Boeing engineers tested their system up to 3,000 volts on new airplanes and then again after the crash of TWA Flight 800, on many older airplanes still in service. No issues were found on any representative aircraft.

The investigators studied it all:

–Misleading. Saying “they studied it all” gives the impression that they proved their theory, which they never did. Neither the NTSB nor any outside group has ever reproduced the energy transfer mechanism officially blamed for the crash using real world electronics available on the accident aircraft.

the chemistry of the fuel, how the fuel/air vapor could ignite, how the flames could move through the wing after bursting from the tank. They established two independent models to simulate the pressure differences inside the wing, a key part of how the fiery fluid would spread. The Safety Board contracted the University of Nevada to analyze the properties of jet fuel vapor. The team ran hundreds of simulations, brought in Boeing engineers to assess the damage of the airliner’s remains, and solicited the opinion of an explosives dynamics expert at the California Institute of Technology. There were flight tests done at the same temperature and conditions as TWA Flight 800 and full-scale fuel tank explosion tests conducted in England.

The litany above actually leaves out tests and academic efforts to understand what happened. All this is to say: The study of TWA 800 was not a sealed-off investigation done by a cadre of bureaucrats. The results were meant to be published, shared, and serve as the foundation of new regulations.

–Misleading: The reporter cites a “litany” of tests and simulations carried out by the NTSB, giving the impression that this exhaustive search lends credibility to the official probable cause finding that the fuel tank explosion did indeed cause the plane’s demise. What the reporter does not say is that the NTSB investigators were unable to reproduce the energy transfer mechanisms in real world conditions. He does not mention that the NTSB ended their investigation without ever finding the ignition source for the fuel tank explosion. He does not mention that a fuel tank explosion cannot account for explosive residue found throughout the interior and exterior of the plane, for a random damage pattern inside the plane, for radar returns showing debris leaving the vicinity of the plane at Mach 4 (four times the speed of sound) and other evidence of an exterior ordnance explosion bringing down the plane.

In the end, NTSB found that TWA Flight 800 would not have perished without a flammable fuel/air mix in its central wing tank, but investigators were never sure what sparked the explosion in the first place—the closest they got was “a short circuit outside of the CWT that allowed excessive voltage to enter it through electrical wiring associated with the fuel quantity indication system.”

–Inaccurate. The NTSB never got “close” to this. They only proposed it. There was absolutely no evidence of any short circuit occurring. On the contrary, when the gauge for the system allegedly responsible for the crash (the fuel quantity indication system) was reconstructed, it was in perfect working condition, which led Boeing engineers to conclude that no short circuit of any kind occurred in that system.

The investigation into TWA 800 inspired new FAA regulations in 2008 that required passenger airplanes to have equipment that replaces oxygen inside fuel tanks with an inert gas, like nitrogen.

–Comment: The FAA’s fuel tank inerting rule came out in 2008, twelve years after TWA Flight 800’s demise, indicating that it was not an urgent necessity but an additional precautionary measure triggered by the NTSB’s probable cause finding (which is unproven) and public pressure. Even though last year the FAA proposed a civil penalty of $13.57 million against Boeing for “failing to meet a deadline to submit service instructions that would enable airlines to further reduce the risk of fuel tank explosions,” the size of the fine and the fact that the FAA did not immediately press for retrofitting all aircraft with nitrogen gas systems right after the probable cause determination was made in TWA Flight 800’s case, indicates that exploding fuel tanks are not a significant safety problem. Even now, this rule does not apply to cargo jets, no matter what size they are, and it only requires that aircraft manufactured after 1992 be retrofitted. The majority of 757’s and early 767’s were built before that time. Also, the rule does not apply to wing tanks, only tanks in the fuselage even though two of the NTSB’s examples of fuel tank fires (Pan Am 707 in 1963 and an Iranian Air Force 747 in 1976) were wingtip lightning strikes. The rule also does not apply to foreign registered aircraft and only to Airbus and Boeing models that are US registered. It does not apply to former McDonnell Douglas MD80, MD90, MD11 and 717 models. The airlines fought the implementation of this rule before and since its publication. The rule may slightly improve safety but this has yet to be proven.

To believe a cover-up implies that an entire industry was duped into believing fuel tanks could become bombs if the fuel/air mix was just right.

–Misleading. A cover-up did occur. Investigators in the “TWA Flight 800” documentary do not simply “believe” there was a cover-up, they lived through one. Their first-hand accounts of FBI and NTSB leaders withholding evidence and testimony from public hearings, of certain investigators altering and removing evidence from the reconstruction hangar, and of the intimidation and threats to investigators and witnesses with information challenging the official theory is all presented in the film. The film names the names and shows the faces of those most responsible for misleading the public and the decision-makers at the FAA.

–Inaccurate. The entire industry was not “duped” into believing fuel tanks could explode. They knew this all along, which was why extra protections to prevent electrical energy from entering the tank were implemented decades before the crash of TWA Flight 800. Those measures worked. Since the introduction of Jet-A fuel in 1965, not a single in-flight fuel tank explosion from an internal source has ever occurred—TWA Flight 800 included.

Of course, there have been dozens of similar explosions before and (in foreign carriers) after TWA Flight 800, making the accepted theory all too believable.

–Inaccurate. There have been no “similar explosions” during the flight of any aircraft since the introduction of the very safe Jet-A fuel. One with Jet-A fuel did occur on the ground, on an aircraft in which an after-market high-voltage lighting system was added—a system that was not installed on TWA Flight 800. Nearly all of the other incidents that the NTSB cites either occurred with a more volatile fuel or had some external ignition source such as a bomb or lightning.