Comments on Ryan Mackey’s “On Debunking 9/11 Debunking”
By
October
5, 2007
Note:
Ryan
Mackey’s text is black
Challenged statements are highlighted
Impact and Collapse Claims
The
first portion of Dr. Griffin’s critique addresses NIST’s analysis, focusing on
damage
caused
at impact and factors that led to the eventual collapse of WTC 1 and WTC 2.
Why Did the Airplanes Cause So Much Damage?
Dr.
Griffin argues that the NIST Report overestimates the damage caused by the
initial
impacts,
based on the following reasons:
1.
Designers claimed to have studied aircraft impact prior to the Towers’
construction,
and found that they would have survived the impact of a Boeing
707;
the damage from a 707 and the actual 767’s should be comparable.
2.
Frank DeMartini commented after construction, but
prior to September 11th, that
the
Towers were designed to survive a 707 impact, and that he believed the
Towers
could survive multiple impacts.
3.
Leslie Robertson also claimed the Towers were designed to survive a 707 impact.
4.
John Skilling claimed the Towers would suffer a
“horrendous fire… but the
structure
would still be there” in the event of such an impact.
5.
The NIST Report does not include all of these comments, suggesting bias.
This first topic raised by Dr. Griffin sets the tone of his discussion,
and sets it poorly. Not
one of his points above contains anything other than speculation.
Point
1 is clearly not speculation. Rather, it is testimony by the persons who did
the analysis or had knowledge of the work being done. If someone else had
claimed “the designers must have done this anaylsis”,
that would be speculation. It should be pointed out that claiming that the
designers were lying is clearly speculation. Any judgement about the validity
of the designers’ findings is also clearly speculation because there is no
evidence on which to base this judgement.
In the
NIST Report, specifically NIST NCSTAR1-2 [13], the NIST team calculates a
range
of possible impact damages using highly detailed models of the buildings and
impacting
aircraft. Dr. Griffin has the opportunity to criticize this calculation and its
conclusions,
but does not even mention it in this section. He also has the opportunity to
produce
his own or other researchers’ calculations if those support a different
conclusion.
He
has not done this either. Dr. Griffin is attempting to dispute NIST’s calculations
with
opinions, and does so as a classic “appeal to authority” fallacy. Let us examine
his
arguments
individually:
1. As
Dr.
cursory
study of a high-speed airliner impact was performed in the 1960’s. NIST
was
unable to find this calculation, and apparently Dr. Griffin does not have
access
to it
either. It is fact that structural modeling in
general, impact modeling, and
particularly
fire modeling were dramatically less sophisticated in
the 1960’s, and
thus is it not obvious that such a study would be of any value at all,
On the
contrary, it is obvious that the designers and structural engineering firm’s
representatives thought the study had merit, or they would not be making public
claims. In fact, Ryan Mackey is referencing analyses, which are based on
physical principles that were well known in the 1960’s, to try and refute Dr.
Griffin’s claims.
let
alone superior to the NIST study. The burden of proof remains on Dr. Griffin,
not on
NIST.
The NIST methods and conclusions are available for scrutiny and criticism,
whereas
this alleged calculation is not. No further comment is needed.
Regarding
the comparison between a 707 and 767, this author accepts that
hypothetical
impacts of these two different aircraft could be materially similar in
7
result
despite their differences in mass and maximum speed. This is supported in
evidence
by the qualitatively similar results from American 11 and United 175,
which
were nearly identical aircraft but impacted with a speed difference of
approximately
kinetic
energy. Dr. Griffin’s attention to this point, while valid, is irrelevant.
2. Frank DeMartini’s comment
that “the building was designed
to have a fully
loaded 707 crash into it” [17] (emphasis added) is incorrect.
Robertson’s
testimony (given below) corroborates DeMartini’s
claim that “the building was designed to have a (fully loaded) 707 crash into it” is but is unclear on the
matter of “fully loaded”. Nonetheless, DeMartini does
speculate that “the Towers could survive multiple impacts”.
While
such an impact was considered by the designers, this consideration was not in
response to an
ordinary
design requirement and aircraft impact did not appear in any ordinary
building
code, as explained in NCSTAR1-1 [18]. Any such requirement would be
a
special customer requirement, and without documentation describing this
requirement,
we cannot evaluate it with any clarity. Mr. DeMartini’s
comment is
also
unsupported by any calculation, and thus should be considered as speculative.
Perhaps
his belief was simply mistaken. We cannot seek clarification, because
tragically,
Mr. DeMartini was killed on September 11th.
3.
Dr. Griffin refers to an interview that Leslie Robertson, Engineer of Record
for the
claims
“they were designed to withstand the impact of a Boeing
misleading.
Mr. Robertson’s comments to the BBC, taken in context, include the
following:
We had designed the project for the impact of the largest airplane of
its time, the Boeing 707. The
767 that actually hit the WTC was quite another matter again. First of
all it was a bit heavier than
the 707, not very much heavier, but a bit heavier. But mostly it was
flying a lot faster. And the
energy that it put into the building is proportional to its square of
the velocity, as you double the
velocity, four times the energy. Triple the velocity, eight times the
energy and so forth. [Sic;
actually triple velocity means nine times the kinetic energy.]
And then of course with the 707 to the best of my knowledge the fuel
load was not considered in
the design, and indeed I don't know how it could have been considered.
But, and with the 767 the
fuel load was enormous compared to that of the 707, it was a fully,
fully fuelled airplane compared
to the 707 which was a landing aircraft. Uh, just absolutely no
comparison between the two. [19]
As we
can plainly see, Mr. Robertson does not support Dr. Griffin’s assertions.
He suggests that the
the actual requirement stipulated a much lower speed collision,
City
in the Sky: The Rise and Fall of the
a three-page white paper, dated February 3, 1964, described its
findings: “The buildings have been investigated and found to be safe in an
assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at
Thus,
there exists documentation refuting the recent recollections of Robertson, an
aging retiree. Furthermore, “The
Complete 9/11 Timeline”
[http://www.cooperativeresearch.org/entity.jsp?entity=john_skilling_1]
describes a second study carried out by Robertson later in 1964. Consequently,
these conflicting claims may be regarding separate studies.
Ryan
Mackey fails to point out Robertson’s incorrect assumption the 767 was “fully
fuelled”. Robertson’s conclusion that there is “absolutely no comparison” is
based on his study and an incorrect
assumption regarding the amount of fuel.
with
“absolutely no comparison” between the requirement and the actual events of
September 11th.
Mr.
Robertson also indicates that a thorough analysis would have been impossible
with
the tools of the time. It also bears pointing out that his firm LERA was a
contributor
to the NIST Report, rather than disputing it, as Dr. Griffin suggests.
4. It
is unclear to the author how the late John Skilling’s
comments are at variance
with
the actual events of September 11th – both towers were struck, but remained
standing,
and there were “horrendous” fires. To my knowledge, Mr. Skilling
never
claimed
that the Towers would remain standing indefinitely, particularly given the
fires
and the impossibility of fighting them. Even if
he had, there are no calculations given in support, nor has anyone been able to
replicate such a result. The burden of proof remains upon Dr. Griffin.
This
same criteria (“no calculations given in support, nor has anyone been able to
replicate such a result “) can be applied to the NIST final report. Thus, the
burden of proof remains on NIST or Ryan Mackey if he chooses to defend the NIST
claims.
5. It
is difficult to take this final point of Dr. Griffin’s seriously, for two
reasons.
First, as we have seen above, three of the four
supposedly contrary points of view
appear to confirm NIST’s conclusions rather
than dispute them, and the remaining
point
of contention is so vague as to be unusable. Second, the NIST Report was a
scientific
study, and not in any way required to survey opinions and speculations
prior
to the fact. Unless supported by calculations, which NIST did indeed attempt
to
find [15], such opinions cannot be evaluated for accuracy, and thus are not
relevant
for purposes of the study.
Ryan
Mackey has not demonstrated that “three of the four supposedly contrary points
of view
appear
to confirm NIST’s conclusions rather than dispute them”. No evidence or
testimony is provided suggesting that global collapse would be the expected
outcome.
This
first section closes without Dr. Griffin having raised a single technical
criticism,
either
of his own or produced by any other. Of his five criticisms, three are attempts
to
shift
the burden of proof, one is a gross mischaracterization of a designer’s
opinions, and
the
last is simple well-poisoning. Since there is no technical criticism offered,
the burden
of
proof remains upon Dr. Griffin to demonstrate that NIST’s conclusions about the
aircraft
impact damage are in any way suspect.
Since
Dr. Griffin has failed to introduce any actual criticism, the author is in no
way
obligated
to support the NIST conclusions, but support is easy to provide. For example,
Dr.
Frank Greening has produced a useful whitepaper [20] that, among its other relevant
conclusions,
estimates the pre-impact kinetic energy of the aircraft and the energy needed
to
completely destroy all supports of a single floor of a
that
the aircraft energy (for the slower
greater
than the columns of a single floor could withstand, had the collision been
directed
solely
at the columns.
Of
course, the destructive process was not 100% efficient for
several
reasons: Some energy would be transmitted to the rest of the tower; some was
needed
to destroy the aircraft; more than one floor was struck; a large amount of
debris
passed
completely through the structure; and other building contents including floor
systems,
furniture, exterior cladding, utilities, and interior walls further absorbed
and
dispersed
the impact. Nonetheless, even if 95% of the impact energy is accounted for in
this
fashion, leaving only 5% directed at the columns, we
still estimate that the impact
could destroy one quarter of the columns over an entire floor, which is comparable to the
NIST
findings. Admittedly this is a rough calculation, but it serves as a useful
“idiot
check”
to verify that the NIST conclusions are plausible.
The KE of the aircraft (WTC1) was around 2500 MJ. 5% of that energy is 125 MJ. Wierzbicki (cited by Greening) estimates that the minimum energy required to fail one core column is 51 MJ. Consequently, 125 MJ is enough energy to fail a maximum of two columns. Note that if the energy is evenly distributed for just three columns, none will fail. Clearly the energy was distributed to more than three columns which most likely would result in some damage but no failure. Thus, the “idiot check” is not valid.