What Caused TWA Flight 800 To Explode Mid-Air?

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Despite initial concerns, on November 18, 1997, the FBI concluded that the incident wasn't a result of terrorist activity. The investigation was then continued by the NTSB, which released its findings on August 23, 2000. According to the report, the most probable cause was ignition of a flammable fuel/air mixture in the center wing fuel tank. The energy source of the spark igniting the explosion was never able to be conclusively determined, but according to the report, a short circuit outside the tank most likely allowed infiltration of voltage through wiring of the fuel quantity indication system. Several indicators of electrical anomalies were noted prior to the explosion, backing the NTSB's findings. For example, about 10 minutes after takeoff, the cockpit voice recorder (CVR) captured the flight's captain, Ralph Kevorkian, voicing concerns over "a crazy fuel flow indicator on number four." The fuel quantity probe read 640 pounds, significantly higher than the 300 pounds recorded by the ground refueler. A test run on the probe by the NTSB demonstrated that applying power to one of the wires leading into the gauge would result in a change of several hundred pounds to the digital display.

While the NTSB's findings appeared reasonable on the surface, the public wasn't convinced, and many airline pilots scoffed. According to the naysayers, the only way an airliner could explode mid-air like that was as the result of either a terrorist attack or a military training exercise gone awry. It didn't help that, at the time, the country was in a high state of alert after a series of terrorism-related events. Substantiating the missile theory, preliminary testing of three samples of material from the wreckage indicated the presence of explosive residue. The NTSB was unable to conclusively determine the source of those residues. Additionally, the FBI interviewed 755 witnesses, with hundreds of them claiming to have seen a "streak of light," similar to a flare, ascend from the ground to the aircraft's location in the sky just prior to the explosion.

Further dampening the NTSB's findings, a problem with one of the fuel quantity probes would have needed to exist in order for them to be conclusive, yet all of the probes ultimately passed their tests---including the one with the high reading. The NTSB also claimed that cracked insulation on electrical wires likely contributed to the spark that ignited the explosion, but no cracks were found on the 159 miles of electrical wire recovered from the scene. That said, 16 miles were never recovered, and the offending segment could be among those wires.

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One final theory, and one that's literally out of this world, was posed by an amateur geologist in 1997. He believed that fragments from a large meteoroid exploded in close proximity to the aircraft shortly after penetrating the earth's atmosphere and proposed that the mysterious streak of light many witnessed was its entry path. He also claimed that more than 200 holes found in the fuselage, which the FBI attributed to blast particles originating from within the aircraft, were the result of high-speed meteoroid fragments.

While it's the most benign theory, it wasn't a meteoroid. For one, witnesses claim that the streak of light started at ground level, not outer space. Then again, witnesses aren't the most reliable source, which is why the missile theory can't be substantiated, either. As such, the most probable cause is the one cited by the NTSB, especially given that this isn't the only center fuel tank explosion in a Boeing aircraft. In 1990, the center tank exploded on Philippine Airlines Flight 143, a Boeing 737-3Y0, shortly before takeoff, killing eight. Then, in 2001, Thai Airways Flight 114, a Boeing 737-400, was destroyed by a center wing tank explosion prior to boarding, resulting in a crew fatality. As for the explosive residue found on the wreckage---well, while the NTSB can't be 100% sure, it strongly believes it either came from contamination when the aircraft was used during the Gulf War or, most likely, from an explosive-detection dog-training exercise conducted just a few weeks before the crash. To prevent further incidents, the FAA issued safety changes to the fuel pumps and wiring of all Boeing aircraft with center fuel tanks.