I am not sure why you put so much credibility in their statements as some of those peole are not even engineers. Some of them was just pilots.
many are engineers none
was just pilots but are pilots with engineering digress or directly invoked in NORAD or Air defense and deserving of a great deal of credibility
Here is one paper on why the WTC building collapsed:
http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf
-Zdeněk P. Baant- Engineer Professor at Northwestern
his credentials:
"Engineer Zdeněk P. Baant is best known as a
world leader in scaling research in solid mechanics (16). His research focuses on the effect of structure size on structural strength as it relates to the failure behavior of the structure. He also has made outstanding advances in structural stability (7), fracture mechanics (8), the micromechanics of material damage (810), concrete creep (1113), and probabilistic mechanics (6, 8, 14).
He was elected to the National Academy of Engineering in 1996 and to the National Academy of Sciences in 2002, 1 of only 153 members with such a dual appointment. In his Inaugural Article (1), published in this issue of PNAS, Baant presents a simple justification of the scaling laws for the fracture of quasibrittle materials such as concrete, rock, fiber composites, and sea ice."
http://www.pnas.org/content/101/37/13397.full.pdf
Inaugural Article: Biography of Zdeněk P. Bažant
Civil and Environmental Engineering - Faculty Profile - Zdenek Bazant
"That impact was too much, and no building could possibly withstand such weight, so floor after floor came down in what we call progressive collapse"
Jets hit towers in most vulnerable spots / Killers appear to have known where to strike
-Hassan Astaneh
His Creditentials:
"CEE professor Hassan Astaneh has been teaching at
Berkeley since 1986. He has taught classes on the design of steel structures and advanced steel design engineering mechanics-static. He is an expert in the effects of disasters on steel structures and has testified before Congress on how the structural integrity of the World Trade Center reacted to the terrorist attack."
Engineering News, Date
You might have to read the full article to understand the following quote:
""When that part is wiped out, the structure comes down," Irfanoglu said. "We design structures with some extra capacity to cover some uncertainties, but we never anticipate such heavy demand coming from an aircraft impact. If the columns were distributed, maybe, the fire could not take them out so easily."
Purdue study supports WTC collapse findings - USATODAY.com
Dr. Ayhan Irfanoglu- Engineering professor at
Purdue
Amazing credentials:
Ayhan Irfanoglu - Purdue University
Here is a paper on 9/11 by the 2003 Forensic engineer of the year Paul F. Mlakar:
http://mceer.buffalo.edu/meetings/AEI/presentations/06Mlakar-paper.pdf
Here is a paper by the 2002 Forensic engineer of the year:
Gene Corley | World news | The Guardian
Here is proof that they won that award:
American Society of Civil Engineers (ASCE)
There you go, the 2002 and 2003 forensic engineer of the year winner believes 9/11 was caused by terrorists.
Those people are the top engineering experts that teach at the best engineering schools in the world. They clearly know what they are talking about.