TWA Flight 800

The Boeing 747-100, registration N93119, arrived from Athens at 4:31 PM. During its refueling at JFK, its auxiliary power unit and air conditioning systems were both left running. Scheduled departure time for Paris was 7:00 PM, but the aircraft was delayed for one hour over concerns of a suspected passenger-baggage mismatch.

After takeoff at 8:18 PM, TWA800 was cleared to flight level 130 by air traffic control in Boston. The aircraft cruised at 13,000 feet from 8:27 to 8:30 PM: the captain noted a "crazy fuel flow indicator" on one of the engines. At 8:30, Boston cleared the aircraft to 15,000 feet. After the captain applied climb thrust to the engines, a loud sound was heard on the cockpit voice recorder, and the aircraft exploded in midair.

It took nine months of trawling to recover 90% of the aircraft's wreckage, which was put together like a giant jigsaw puzzle inside an NTSB hangar. Computer simulations indicated an explosion near row 23 in the main cabin: it was never totally clear what caused the explosion. Explosive residue was found inside the aircraft, but is now believed to have been left behind from a police training exercise in St. Louis several weeks before the crash.

Initially, many pundits believed that TWA800 may have been downed by a surface to air missile: some believed that it was downed by an errant US Navy warhead. The FBI investigated these claims and even fired missiles at a mockup in the desert, but in 1997 ruled that the airplane was not downed by a criminal action, and called off their investigation.

The National Transportation Safety Board ruled the probable cause of the disaster on August 22, 2000:

An explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. The source of ignition energy for the explosion could not be determined with certainty, but, of the sources evaluated by the investigation, the most likely 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. Contributing factors to the accident were the design and certification concept that fuel tank explosions could be prevented solely by precluding all ignition sources and the design and certification of the Boeing 747 with heat sources located beneath the CWT with no means to reduce the heat transferred into the CWT or to render the fuel vapor in the tank nonflammable.

Okay. A brief bit of back-of-the-envelope analysis follows.

Engagement Envelope. Every SAM has an 'engagement envelope,' which is a range of distances to and speeds of the target within which it is able to engage said target. Bluntly, if a target is too far away and/or going too fast, the missile won't have enough delta-v to reach its target and will either fall to the ground or in some cases refuse to launch. In this case, the fact that the aircraft had spent several minutes at 13,000 feet just prior to the incident means that MANPADS is out. There are few (if any) man-portable SAM systems that can engage a fast-moving target (i.e. faster than a helicopter) at that speed and that altitude.

Damage Profile. MANPADS and other IR SAMs are unlikely for another reason - the location of the explosion. The NTSB report states that the explosion occured near Row 23 within the fuselage. The wreckage shows that the explosion threw pieces of the airplane out rather than punched the skin inward. Infrared seeking missiles will detonate on or near the engines of the target; that's what they are homing on. Even those with logic contained in the fusing designed to increase the chances of a fuselage hit aren't given the profiles of airliners; at most, they will attempt to strike forward of the 'hot spot' - which is where the body of a warplane is. In addition, no fragments of any weapon were found - and even more than a bomb on board, a missile would leave pieces of itself in the area and embedded in the target.

Radar SAM Requirements. Of course, radar-guided missiles would tend towards the center of the target. There are a few problems with this solution, however. Radar-guided SAMS are (with a very few exceptions) not 'hit-to-kill' weapons; they have fusing which detonates them when they get near their targets, so as to increase their chances of a hit. Given that, it is highly unlikely that a radar-guided SAM could produce an explosion 'within the airframe' of the airplane. Finally, such missiles are larger and more complex, and would be even more likely to leave large identifiable bits of themselves lying about. Finally, radar-guided SAMS need a radar! At this point, you'd need a ship or another aircraft equipped with tracking and guidance radar which guided the missile to Flight 800. This would mean that those firing the missile expected to see a large jet aircraft in their sights; especially given the location, this is not likely (unless, of course, they were ordered to shoot down TWA 800 specifically!)

It may be more fun to believe that there are deeper events than those we can see. However, in this case, positing a missile as the cause of TWA 800's demise introduces far more questions (and requires many more assumptions) than the official reasoning.