SPECIAL REPORT. Those who expected new, explosive details of the crash didn't understand what the week-long hearings were about: to give the NTSB a chance to show how good they are at what they do, and to put pressure on the FAA and industry. The hearings accomplished that and more, but failed to address a key question: whether it makes sense to spend millions to make an almost-perfectly-safe airplane like the 747 ever-so-slightly safer?
December 14, 1997
Last year's TWA 800 accident
generated an extraordinary amount of public and media interest, perhaps because,
thankfully, airplanes don't often turn into fireballs and fall out of the sky in pieces.
Its aftermath has only emphasized the peculiarities of the incident and heightened our
awareness of the political nature of reaction to such tragic events. The initial response
to the elderly 747 exploding on initial climbout from JFK was that it must have been a
terrorist act, preferably of the Middle-Eastern sort. Seizing upon the politically
opportune moment to make points, the Administration immediately jumped on that bandwagon,
and the Gore Commission was appointed to take over the normal security and safety duties
Although NTSB Vice-Chairman Robert Francis was nominally in charge of the
investigation, then-DOT Secretary Federico Pena took control of the media aspect of the
accident investigation, and the prime-time TV opportunity, from the NTSB and, for that
matter, the FAA. Fair enough from a political point of view a few short months before
Francis had already garnered more than his share of TV prime time in the Florida swamps.
Find the cause, or apprehend the perps?
By now, it seemed that nothing about the accident should
have surprised even the most hardened aviation observer, but as airplane bits were being
painfully dredged up off Long Island's south shore, the FBI stepped in to take over the
investigation from NTSB. The bureaucratic infighting and public clashes that ensued were a
new sideshow, particularly to the NTSB, which historically has attempted to maintain an
open mind and make no comments on causes of an accident until it issues its accident
report. In the politically charged atmosphere since the ValuJet crash, that has become
something of an exception to the rule, unfortunately.
Showing no such rectitude, the FBI, having seemingly already made up its mind, pursued
a parallel investigation, often interfering with the efforts of the NTSB's experienced
professionals, looking for evidence to fit its criminal theories. As time went on, and as
it became more and more apparent that public and political interest was waning and that
the FBI knew very little about aviation accidents, it slipped into the background,
formally bowing out earlier this month, just before the start of the NTSB public hearing
on the tragedy. Thefts of wreckage bits by ghoulish conspiracy theorists and Pierre
Salinger's bizarre discovery of the World Wide Web added color to the mix, and set the
stage for this week's hearings.
Hey, mom, I'm on TV!
The NTSB's hearing is the first that has
received gavel-to-gavel TV coverage, albeit on the seldom-watched-outside-the-Beltway
C-SPAN, and initial general media interest was considerable, reviving interest in the
accident. NTSB accident hearings are usually pretty chaired by the investigator in charge,
but not this time. NTSB Chairman Jim Hall, taking advantage of the media opportunity,
displaced Bob Francis behind the gavel, and Francis was seen dutifully making the
Washington aviation Christmas party circuit, far from the scene of the action at the
Baltimore Convention Hall. A few DC wags wondered if it could be that Jim Hall, an Al Gore
chum, was being given some popular exposure in anticipation of a more public role in the
coming presidential campaign.
Those who expected the hearings to reveal new, explosive details of the crash the
general media, victim's relations and the like were to be sorely disappointed by this
week's events in Baltimore. They didn't understand the basic concept of these hearings,
which is to put the accident evidence before the public, as well as to give the public a
view of how the investigation was conducted. In the light of the constant harping from
various sectors on how long this investigation took, the expense and the lack of results,
this hearing, more than others, was also a public platform for the NTSB to show just how
good they are at what they do, even though they still haven't yet found a definitive
answer as to the cause of the accident.
NTSB detractors, meanwhile, also had their day, using
the attention of the media on the hearings to independently point to perceived errors and
omissions on the Board's part, and on the part of the FAA. Ex-DOT Inspector General Mary
Schiavo used the opportunity to again blast her old nemesis, the FAA, and to plug her book
and enhance her marketability.
The hearings opened in concert with the very public arrest of a TWA pilot, a writer and
his TWA flight attendant wife, who were alleged to have stolen TWA 800 wreckage bits from
the assembly hangar on Long Island in pursuit of a conspiracy theory and profits from the
sale of a book on the subject of the accident. That was followed by an exhaustive parade
of witnesses testifying to the lack of bomb, missile or meteor evidence, all of which
should be enough to permanently silence conspiracy theorists, but we all know better,
These initial carnival events drew the crowds and made the headlines, but were only the
warm-up for the more serious aspects of the hearings, which outlined the possible causes
and some possible corrections for the problems uncovered by the investigation. Once the
initial show was over, the hearings were rapidly relegated to the back pages and the real
work got underway.
Why'd the fuel tank explode?
These problems centered on the three factors
needed to cause a fire ignition, fuel and an oxidizer. On the ignition front, the aging
aircraft discussion was renewed (the press and some vocal "survivors" groups are
fond of the issue, one group urging the grounding of all "classic" 747s), and
centered itself on the wiring in the fuselage tank. General aviation pilots have been
taught not to pay any attention to the generally wildly inaccurate fuel gauges in their GA
aircraft, but because they don't visually check the tanks, keep accurate time records of
fuel burned, or use electronic fuel-flow meters, airlines rely on fuel gauges. Not the
notoriously imprecise cork-and-float, all-the-electrics-safely-outside-the-tank designs
used in our lowly bug-smashers, but remarkably accurate fuel gauges that have electronic
sensors in the tanks, and the concomitant electrical wiring. Electrical wiring inside the
fuel tank? Yup!
This wiring is subject to all the risks that the wiring
in the rest of the airplane is subject to, abrasion, flexing, corrosion, heat damage and
the like. Worse, being inside the tanks it doesn't get looked at very often, and if
something goes wrong with it, the location is far from ideal. Some corrosion and abrasion
damage was found on TWA 800's wiring, but not enough to be conclusive tied to the
explosion. The most constructive solution proposed for this problem was the obvious one
that is, to get the sensors out of the tanks, by replacing them with external
"radar-like" sensors like those already used on the Boeing 777. However, no
information was offered on retrofitting possibilities or the expense involved.
The fuselage tank's fuel scavenge pump was never found, and it is deemed quite possible
that this either leaked or caught fire, particularly since there had been a problem with
leaking O rings in these pumps. With no pump to examine, however, there is no way to
positively link it to the explosion. Boeing says it is considering a modification to the
fuel scavenge pump to eliminate the possibility of fire reaching the tank, even if the
pump catches on fire.
If he were still with us, Rudolph Diesel would
be glad to tell us that a source of fire isn't always needed for combustion. The NTSB is
concerned that heat from the air-conditioning packs (just below, and sharing a common wall
with the tank), weather, and the effects of the climbout might have caused or contributed
to the fire. The heat load would certainly have contributed to the vaporizing of the small
amount of fuel left in the nearly empty tank. It conceivably could have gotten hot enough
to reach the flash point of the fuel and air mixture, initiating the explosion.
Only dollars away from a solution?
To cure this potential problem, both active and passive corrections were considered.
The passive approach involves the military practices of using JP-5 fuel rather than Jet-A
(JP-8), and of foam filled tanks. From the tenor of these presentations and discussions,
it became clear that a world-wide switch to JP-5 is likely, if fuel refiners can meet the
demand, an open quesdtion. An increase in cost of approximately 2 cents a gallon (if
manufactured in large quantity) more than Jet-A and slightly harder starting when
cold-soaked were brought out as the only problems. These, then, in return for a 40 degree
Fahrenheit reduction in flash point, which would result in "a 20-fold increase in
safety," according to the FAA. Foam filled fuel tanks reduce sloshing and keep fuel
liquid longer, lessening the rate of vaporization, and reduces explosion damage by
absorbing the shock wave. It does appear to have some formidable downsides, including
increased weight, reduced fuel capacity and long-term maintenance problems both with
possible foam deterioration and tank repair.
The issue of heat from the air-conditioning
packs wasn't considered as a subject for remedial action. The possibility of shutting down
the air-conditioning when wall temperatures reached a specified level (either
automatically or manually) in current aircraft, and moving the air-conditioning packs in
future production didn't seem to occur to any of the panelists, or at least it wasn't high
on anyone's agenda, and was not brought up for consideration.
Active control centered on the concept of inerting the tank, either by replacing spent
fuel with inert nitrogen (filling the empty volume and thereby preventing vaporization) or
via forced air circulation that would prevent buildup of fuel vapors. Systems such as
these are used on some military aircraft. While conceptually appealing, it became clear
that expense (particularly in retrofitting) and weight considerations, upwards of a ton,
make these systems impractical in the short term. Not that impracticality or outrageous
cost ever stopped the NTSB from demanding something be done.
The hearing concluded with no final finding of the cause, which is fairly unusual, but
the fact that the fuselage tank exploded is now generally accepted by all but the fringe.
The NTSB is recommending action by the FAA to reduce the future possibility of a
recurrence by reducing tank temperatures, fuel flammability, and eliminating electrical
sources of ignition from the tanks. Boeing, meanwhile, is considering a redesign of the
tanks to reduce temperatures.
The FAA, meanwhile, made lots of promises to
investigate the issues, but skeptics noted this is SOP for the agency. Other noted that
the FAA has already taken some meaningful remedial action, though hardly enough to satisfy
Hall. Cynics noted that none of the FAA's actions to date would seriously affect the
airlines' bottom lines.
Jim Hall, a relative newcomer to aviation, but no neophyte in politics, ran the show
admirably, and only infrequently let his lack of aviation or technical background show. He
masterfully used every opportunity to put pressure on the FAA. After five days, what did
come through was his trust in, and reliance on the real pros at the NTSB, not the board
members, but the accident investigators and other civil service types who do the grunt
work and supply the technical knowledge. Still, those who had any doubts that this was an
inside-the-Beltway political show should have had them dispelled when the FAA's Tom
McSweeney, Director of the Office of Certification, talked of "synergizing the
information and moving forward."
Boeing 747 has an absolutely superb safety record. How much safer does it need to be?
...and is it really worth the cost?
Neither those who testified at the public hearing, nor the talking heads who commented
upon it on TV or radio had the nerve to raise what may be one of the most important
issues: whether it is really worth the millions upon millions it will cost to make an
almost-perfectly-safe airliner ever-so-slightly safer, and by a statistically
insignificant amount? One must wonder why it is that the tragic deaths of 230 people
aboard TWA 800 is dealt with so obsessively by people who don't even blink when 2,300 or
23,000 deaths occur on our highways, many on the way to ride in those far-safer airliners.
Surely those deaths (by ones and twos and fours for the most part) are just as tragic.
At what point do we reach the realm of diminishing returns for the safety dollar?