Debunked: Demolition “squib” is visible at top of WTC North Tower before Flight 11 crash

[Marc Powell]

It is claimed by conspiracy theorists that mistimed demolition explosions, that they refer to as "squibs," can be seen at various times and at various places before the collapse of the WTC twin towers. At the 51:50 mark in the 2014 David Hooper film, The Anatomy of a Great Deception (viewable in its entirety at youtube.com/watch?v=l0Q5eZhCPuc ), Hooper makes reference to one particular squib that he claims was detonated shortly before the AA Flight 11 impact. He tells the audience the following:

Not all squibs, however, were easy to spot. Remember how we discussed explosions that were timed to go off with the plane impacts? Well, this is the first plane impact. Notice the dark brown smoke coming out of the top floor of the tower. This smoke is already dissipating before the plane strikes the building.

Below is the accompanying clip from Hooper's film:

In the video clip, taken from the Naudet Brothers video, there definitely is a mysterious dark brown cloud visible near the top of the tower that appears to be present even before the fireball from the plane crash ascends to that level. However, it was not present before the plane impact, is not the result of a demolition charge explosion and is not even smoke, for that matter. Hooper's video clip starts after the plane impact which conceals the fact that there actually was no smoke visible beforehand. And the clip is freeze framed right after the mysterious cloud has been zoomed into view which conceals the fact that the smoke just hangs in the air and does not move upward as hot smoke from an explosion would be expected to do. This is more clearly visible in the unedited version of the video viewable at youtube.com/watch?v=7g6V8KZE3GA . Here is a clip from it:

The mystery of the brown cloud is solved in Chapter 6 of the NIST report NCSTAR 1-5A, which contains a detailed analysis of the Naudet Brothers video of the Flight 11 impact. On page 56, it says the following:

Here are the diagrams of the ventilation louvers referred to in the NIST report:

So then, the brown cloud at the top of the North Tower was merely dust that had accumulated in ventilation louvers on the 108th and 109th floors that supplied fresh air to the floors where the aircraft impacted. The pressure wave from the crash forced the dust in the louvers to be violently expelled resulting in visible dust clouds on the north and east sides of the building. One has to wonder why David Hooper and his team of diligent researchers, including Technical Director, Richard Gage, could not have read the report they so vehemently criticize and figured this one out on their own.

 

[Nada Truther]

It is claimed by conspiracy theorists that mistimed demolition explosions,

I know that what you said is not a direct quote, but your opinion or paraphrasing many of the statements that the truther community has uttered over the years; but, It always amazes me that truthers can talk about the unbelievable amount of precision timing that it would take to pull this whole "job" off and how so many things are conveniently "mis-timed", to suit their narrative. You would think that this sort of thing would have been the easiest thing to time.... remotely detonate along with the first impact would be the only thing that you probably could get exactly timed right; but they missed on this one?

 

[Marc Powell]

I know that what you said is not a direct quote, but your opinion or paraphrasing many of the statements that the truther community has uttered over the years; but, It always amazes me that truthers can talk about the unbelievable amount of precision timing that it would take to pull this whole "job" off and how so many things are conveniently "mis-timed", to suit their narrative. You would think that this sort of thing would have been the easiest thing to time.... remotely detonate along with the first impact would be the only thing that you probably could get exactly timed right; but they missed on this one?

The "precision timing" that seems the most improbable to me is the sequential timing of the demolition blasts that would have been required on each floor in order for the top-down demo job to look like it was driven by gravity (at approximately 2/3 G). Even truther physics teacher, David Chandler, who touts the theory that material was sequentially removed forming a hole ahead of the descending "demolition wave," glosses over the impossibility of such spectacularly precise explosion timing.

 

[AmberRobot]

The "precision timing" that seems the most improbable to me is the sequential timing of the demolition blasts that would have been required on each floor in order for the top-down demo job to look like it was driven by gravity (at approximately 2/3 G). Even truther physics teacher, David Chandler, who touts the theory that material was sequentially removed forming a hole ahead of the descending "demolition wave," glosses over the impossibility of such spectacularly precise explosion timing.

If the explosives were there to make it look like a gravity-driven collapse, why do the truthers claim that it is *obviously* a demolition?

 

[Marc Powell]

If the explosives were there to make it look like a gravity-driven collapse, why do the truthers claim that it is *obviously* a demolition?

They don't understand the simple physics behind the pancake collapse of floors in the open office spaces. And the statements of pseudo-experts like David Chandler leave them no option but to assume it was "obviously a demolition."

 

[AmberRobot]

They don't understand the simple physics behind the pancake collapse of floors in the open office spaces. And the statements of pseudo-experts like David Chandler leave them no option but to assume it was "obviously a demolition."

But the claim was that the explosives were there to make it *look like* a gravity collapse. So if it *obviously* looks like a demolition then the demolitionists did a terrible job, right?

 

[Marc Powell]

But the claim was that the explosives were there to make it *look like* a gravity collapse. So if it *obviously* looks like a demolition then the demolitionists did a terrible job, right?

I am not sure I understand your syntax. The "demolitionists" don't claim the explosives were there to make the collapse look like it was gravity-driven (it was). They claim that the explosives were timed to make the demolition resemble a gravity-driven collapse so as to hide its true nature.

 

[AmberRobot]

I am not sure I understand your syntax. The "demolitionists" don't claim the explosives were there to make the collapse look like it was gravity-driven (it was). They claim that the explosives were timed to make the demolition resemble a gravity-driven collapse so as to hide its true nature.

And my point is that despite all their effort the truthers claim it is *obvious* that it was a demolition, so the effort to make it look like it wasn't failed completely. Maybe we just aren't understanding each other. I'll quit while I'm behind…

 

[Marc Powell]

And my point is that despite all their effort the truthers claim it is *obvious* that it was a demolition, so the effort to make it look like it wasn't failed completely. Maybe we just aren't understanding each other. I'll quit while I'm behind…

Okay, I think I now understand what you are getting at. What the truthers are claiming is that the buildings could not have collapsed in the manner they did without precisely-timed (and apparently silent, flashless and blastless) explosives. So, regardless of how successfully the demolitionists may have gotten the silent, flashless and blastless explosives to simulated a gravity driven collapse, it wasn't physically possible and so, CD is obvious.

 

[AmberRobot]

Okay, I think I now understand what you are getting at. What the truthers are claiming is that the buildings could not have collapsed in the manner they did without precisely-timed (and apparently silent, flashless and blastless) explosives. So, regardless of how successfully the demolitionists may have gotten the silent, flashless and blastless explosives to simulated a gravity driven collapse, it wasn't physically possible and so, CD is obvious.

Yes. And if it was so obvious to truthers why did the demolitionists go through such an elaborate plan to to try to make it look like a gravity collapse? Wouldn't it have been obvious to them as well?

 

[Marc Powell]

Yes. And if it was so obvious to truthers why did the demolitionists go through such an elaborate plan to to try to make it look like a gravity collapse? Wouldn't it have been obvious to them as well?

Logic has no place in the truther psyche.

 

[Jeffrey Orling]

Gravity is what makes things fall... The issue re the buildings is what caused the structures to loos capacity locally and ultimately globally to resist gravity? RESISTING gravity is what structure does. There was no evidence of explosive or other CD at the WTC. The was evidence of unfought fires and mechanical damage both which destroyed the integrity and capacity of the structural members to perform per their design criteria.

 

[Mendel]

Logic has no place in the truther psyche.

I wouldn't say that. Much of what they do and think involves logical patterns.

The crux is that belief makes logical contradictions seem meaningless, along the lines of "I'm probably simply missing something here", "someone is going to figure this out eventually", or "we're being lied to, and misled".

 

[investigating911]

Here are some rare pictures I found of just after the first plane crashed into the north tower

source: https://www.skyscrapercity.com/threads/world-trade-center-on-9-11.659642/page-69#post-175321323

What these photos appear to show is that just like with the south tower, there was ejection of grey/white crushed concrete, mangled steel, aluminum (both from the cladding and airplanes) and fire from the side of the face hit by the airplane.

Given that most of the airplane managed to get into the building and significant portions were ejected out of the diametrically opposite face, this shows that from the airplane exited and entered, there was ejection of squib looking fire and dust explosions, with the explosion of material away from the impacted face of the building likely being from parts of the middle and end portions of the aircraft breaking up and falling to ground level before the had fully made it into the tower.

The momentum of the traveling disintegrating airplane and jetfuel explosion would have funneled most of the debris to the south, but a lot of debris would have still exploded out of the east and north faces, moving in a direction that is at an angle or even opposed to the momentum of the main, initial explosion.

Had the airplane been traveling slower, this is probably what would have been seen instead (see first and third tries, as opposed to second try where the airplane fully makes it into the building but there is still some debris from the tail end of the aircraft falling out of the impacted face and down to the ground away from the impacted face).


Source: https://www.youtube.com/watch?v=kdoWkEv9ufc


The wind blowing from the northwest on that day would causing the debris from the end of the plane and blown off north face cladding to travel to the southeast as they fall, away from the north face of the building, with most of that debris probably eventually landing near the east face of the building.



According to the following paper, both aircraft were traveling fast enough that deformation and disintegration of the wings from impacting the exterior columns wouldn't have been enough to slow down the wings and prevent them from penetrating the exterior facade.
https://www.sciencedirect.com/science/article/abs/pii/S0734743X02001069

 

[Jeffrey Orling]

Here are some rare pictures I found of just after the first plane crashed into the north tower

source: https://www.skyscrapercity.com/threads/world-trade-center-on-9-11.659642/page-69#post-175321323

What these photos appear to show is that just like with the south tower, there was ejection of grey/white crushed concrete, mangled steel, aluminum (both from the cladding and airplanes) and fire from the side of the face hit by the airplane.

Given that most of the airplane managed to get into the building and significant portions were ejected out of the diametrically opposite face, this shows that from the airplane exited and entered, there was ejection of squib looking fire and dust explosions, with the explosion of material away from the impacted face of the building likely being from parts of the middle and end portions of the aircraft breaking up and falling to ground level before the had fully made it into the tower.

The momentum of the traveling disintegrating airplane and jetfuel explosion would have funneled most of the debris to the south, but a lot of debris would have still exploded out of the east and north faces, moving in a direction that is at an angle or even opposed to the momentum of the main, initial explosion.

Had the airplane been traveling slower, this is probably what would have been seen instead (see first and third tries, as opposed to second try where the airplane fully makes it into the building but there is still some debris from the tail end of the aircraft falling out of the impacted face and down to the ground away from the impacted face).


Source: https://www.youtube.com/watch?v=kdoWkEv9ufc


The wind blowing from the northwest on that day would causing the debris from the end of the plane and blown off north face cladding to travel to the southeast as they fall, away from the north face of the building, with most of that debris probably eventually landing near the east face of the building.



According to the following paper, both aircraft were traveling fast enough that deformation and disintegration of the wings from impacting the exterior columns wouldn't have been enough to slow down the wings and prevent them from penetrating the exterior facade.
https://www.sciencedirect.com/science/article/abs/pii/S0734743X02001069

Nonsense. The momentum / energy of the plane and its parts were more than enough to deform, tear through and penetrate the towers. Engines were quite massive and the fuel tanks in the wings the same. Sure some things broke off and fell outside the tower... but most ripped right into and through it.

 

[Marc Powell]

Nonsense. The momentum / energy of the plane and its parts were more than enough to deform, tear through and penetrate the towers. Engines were quite massive and the fuel tanks in the wings the same. Sure some things broke off and fell outside the tower... but most ripped right into and through it.

You've got that right. I don't know why it is so difficult for some people to understand the simple mechanics of the plane impacts. The planes penetrated the buildings mostly by breaking apart exterior columns at their bolted connections, with a few columns actually being cut by the impact. Momentum carried most of the wreckage and building rubble into the building. The NIST and FEMA reports have extensive diagrams and photos showing which columns were dislodged, which were severed, which were bent inward and which managed to stand up to the impact of the lighter parts of the wings and tail. Millions of people saw and heard the plane crashes in person or on live television. It is absurd to question whether what happened was in violation of physical principles and to suggest that something else should have happened.

 

[Jeffrey Orling]

Truthers can sell their nonsense because tall buildings don't collapse on their own... they don't burn down... But they are taken apart piece by piece...or demolished with explosives. I suppose people expected that the planes would knock them over...
Fantasy is an easy to sell to naive, ignorant and willfully ignorant people.

 

[investigating911]

Nonsense. The momentum / energy of the plane and its parts were more than enough to deform, tear through and penetrate the towers. Engines were quite massive and the fuel tanks in the wings the same. Sure some things broke off and fell outside the tower... but most ripped right into and through it.

Yes but I think that's only because the plane was traveling fast enough. Had it been flying at normal speed for that altitude or in the situation the towers were designed for (flying slowly and trying to land because of a failure aboard the aircraft), I don't think the plane would have penetrated the building fully without disintegrating.

Nevertheless, in pictures of the plane impacts you can see that despite the high speed of the aircrafts, there does appear to be debris from the end of the plane that breaks off and falls to street level in front of the impacted facade of the tower.

That can be seen in the following pictures of plane impacts on the south tower:

 

[Jeffrey Orling]

Normal speed they would still penetrate the facade

 

[Landru]

Yes but I think that's only because the plane was traveling fast enough. Had it been flying at normal speed for that altitude or in the situation the towers were designed for (flying slowly and trying to land because of a failure aboard the aircraft), I don't think the plane would have penetrated the building fully without disintegrating.

Do you have any evidence to support this assertion?

 

[investigating911]

Do you have any evidence to support this assertion?

https://www.sciencedirect.com/science/article/abs/pii/S0734743X02001069

It says in the article (paywalled) that "Using the exact dynamic solution in the membrane deformation mode, the critical impact velocity to fracture the impacted flange was calculated to be 155 m/s for both flat and round impacting mass." and that

"The problem can be then modeled as an impact of a rigid mass traveling with the velocity of 240 m/s into a hollow box-like vertical member."

So if the planes were traveling slower than 155 m/s, this paper seems to indicate that the airplane wings would not have been able to fully fracture the hollow box-like exterior columns.

Normal speed they would still penetrate the facade

So is the debris falling out of the impacted face all alumnium building cladding and content then and not the severed aluminum from the rear and tail part of the jet plane?

Eyewitness accounts say that the tail end of for example the UA175 airplane came crashing down onto Liberty Street
https://sites.google.com/site/911stories/insidethesouthtower:eyewitnessaccounts

It progressed down the building, breaking the windows as it went; the entire building was groaning, an unnatural, unearthly sound, much like a can squeezing, or cracking uncooked spaghetti. By the time it reached the lobby, the marble veneer was cracking and falling off the walls; the chandeliers shattered on the floors along with the plaster ceiling, and the force imploded in at about 50 mph, pulling metal, balled safety glass, and other material with it. The pipes were bursting over my head and dense materials were flying around me as if they were being pureed in a blender. In the next instant came a horrible noise and a flash of extreme heat and light blown directly over my head. I concluded later in the day that this was from the huge airplane fireball sent down the 78-110 elevator shaft that exploded out into the lobby, and blew around the walls and curled into the center vestibule where I was taking cover. The third and last explosion occurred when a huge chunk of burning wreckage fell to Liberty Street, which runs parallel along the south side of the South Tower, and crashed through the building into the lobby behind me, bringing metal, glass, marble and revolving doors with it. There had been four security men and some fleeing WTC workers behind me near those revolving doors; I realized that they were all taken out by either a huge chunk of the building exploding outwards or the tail end of the plane falling to the street. I now know that there were nine of us in the lobby that day when the plane hit, two NYPD officers on the 44-77 elevator side, and two others coming out of emergency stairwells on the 78-110 elevator side. The two officers and I were the only ones who made it out alive.

 

[Mendel]

So if the planes were traveling slower than 155 m/s, this paper seems to indicate that the airplane wings would not have been able to fully fracture the hollow box-like exterior columns.

For comparison, this is the speed limit for an aircraft flying circles waiting:

Article:

International Civil Aviation Organisation (ICAO) maximum holding speeds are as follows:

• Holding altitude 14000' or below - 230 KIAS

Source: https://www.skybrary.aero/index.php/Holding_Pattern

230 knots indicated air speed translates to 118 m/s plus/minus the wind speed. (A 155-118=37m/s wind is a hurricane.)

 

[Gamolon]

Had it been flying at normal speed for that altitude or in the situation the towers were designed for (flying slowly and trying to land because of a failure aboard the aircraft), I don't think the plane would have penetrated the building fully without disintegrating.

And what were the towers designed for?

From everything I have read, the towers were able to absorb an impact (the building as a whole structure, not just the façade) from a plane and remain standing. I have never seen any analysis from any engineer involved in the original design process that says the façade would have resisted the impact and the plane would have disintegrated without penetrating it.

According to Leslie Robertson:

Testing such a horrific hypothesis comes down to two basic conditions: removing a series of adjacent columns and floor trusses and seeing how the buildings absorb the energy of the jet. Robertson says tests revealed that if a plane was flying at approach speed when it struck one of the towers, it would remain standing.


However, the impact that a jet-fuel-accelerated fire would have on the integrity of the structures was never projected. The reason, according to Robertson: No one knew how to model such a fire.

https://www.nj.com/news/2011/09/the_world_trade_center_work_of.html

Also keep in mind the the resultant fires from such an impact and their affect on the structure were never analyzed.

 

[Gamolon]

Had the airplane been traveling slower, this is probably what would have been seen instead (see first and third tries, as opposed to second try where the airplane fully makes it into the building but there is still some debris from the tail end of the aircraft falling out of the impacted face and down to the ground away from the impacted face).


Source: https://www.youtube.com/watch?v=kdoWkEv9ufc

Are we supposed to take the above video as a serious representation of what SHOULD have happened?

For crying out loud, the wingspan of a 373 is 117'-5" and the video shows the wingspan being wider than the façade which was 208' wide. The video implies the 373 wingspan is around 380'!

 

[investigating911]

And what were the towers designed for?

From everything I have read, the towers were able to absorb an impact (the building as a whole structure, not just the façade) from a plane and remain standing. I have never seen any analysis from any engineer involved in the original design process that says the façade would have resisted the impact and the plane would have disintegrated without penetrating it.

I'm not questioning that. I have no doubt that at the speed the planes were traveling, they would fully penetrate the building. However, I was wondering whether despite the planes fully making it into the building, whether the explosions from the impacted face contained a lot of plane debris from the rear and tail end of the plane. I see a lot of what appears to be aluminum parts in the explosion coming out of the impacted face. I don't think that was all building cladding.

I was also wondering whether a plane traveling at a slow speed and making a crash landing would be able to fully make it into the building, or whether it would look more like no-planers imagine such a situation would involve (such as only the front of the plane lodging itself into the building, with the rest of the plane breaking apart and falling to street level).

According to Leslie Robertson:

https://www.nj.com/news/2011/09/the_world_trade_center_work_of.html

Also keep in mind the the resultant fires from such an impact and their affect on the structure were never analyzed.

Yes, I don't subscribe to the idea that the towers were designed to structurally withstand the impact of a fully loaded transcontinental 767 airliner crashing into them. I know that such studies when the towers were being constructed never took into account the effects of fire.

Are we supposed to take the above video as a serious representation of what SHOULD have happened?

No I never said that. But I asked if the plane was flying slower and/or at a steeper angle, wouldn't that be how the plane crash would look (i.e. the plane would be lodged into the building but not penetrate fully)?

For crying out loud, the wingspan of a 373 is 117'-5" and the video shows the wingspan being wider than the façade which was 208' wide. The video implies the 373 wingspan is around 380'!



View attachment 47241

I couldn't find a better representation of a situation where an airplane would be flying into a tube framed steel structure at a lower speed. The airplane is too big compared to the building, but that seems to be the case in most simulations of airplane crashes in physics games that I was able to find.

 

[JMartJr]

This is not a good model but I cannot find a better one -- that still leaves the model as still not being very good. I'm not sure how much can be learned from an incorrect model.

 

[AmberRobot]

This is not a good model but I cannot find a better one -- that still leaves the model as still not being very good. I'm not sure how much can be learned from an incorrect model.

An incorrect model is usually worse than no model if you're trying to learn something.

 

[Oystein]

The notion that the towers were "designed to" withstand a plane crash is mostly a myth. This was NOT in any way a design objective that structural "designers" were considering when drafting and finalizing the "design" of the towers' structure.

Instead, it was merely an afterthought: Someone asked in the mid-60s, when enemies of the WTC project tried to derail the whole project by scaring the public and suggesting such towers would not survive a jet impact like the 1940s B-25 into the Empire State Building, only with bigger, faster planes: Would the towers, as already designed, survive a plane crash?

And so the structural engineers did a couple of back-of-the-envelop calculations - assuming a 707 at cruising speed (not, as Robertson would recall decades later, at low landing speed):

1.) Assuming the 707 would cut external columns along its entire wing span, would the remaining wall assembly (plus hat truss) be able to re-distribute loads without making any more columns fail? They figured that yes, this would be the case.

2.) Would the lateral impact forces bend the tower so badly at their most stressed locations (this would, presumably be the perimeter not much up from ground level on the side opposite to where the impact is) that it would fail there? They figured that that lateral force would be slighty (like 30%) higher than the lateral force of a maximum design wind load (at hurrican windspeed of xxx mph), and thus mostly likely be within the margin of safety, so no, the tower would not fail in bending (but the forces would come close to a magnitude where the odds for immediate failure would be scary)

And so, plane impact of speedy 707 (very similar in both speed and wingspan and mass to the actual 767 impacts) would not make the structure fail immediately from overstressing columns.

No consideration was given the effect of subsequent fires, as has been pointed out.
Nor was any consideration given what damage there would be to the floor structure and in turn the effect of that on the columns; nor if and how core columns would be affected.
Nor was any attempt made to calculate in any detail how columns would react to such impacts - bend, break, tear, snap connections, whatever. They just "cut" them in their model, as if by a giant scalpel from the heavens.

The real world tests of 9/11/2001 proved the qualitative correctness of these quick-and-dirty 1960s after-though calculations.



Details to all of this in "City in the Sky" by James Glantz.

 

[Jeffrey Orling]

While the towers stood after the plane slammed into them.... escape roots were destroyed and too many people could not exit.

 

[Edward Current]

"The problem can be then modeled as an impact of a rigid mass traveling with the velocity of 240 m/s into a hollow box-like vertical member."

I'm just a caveman, but this sounds like a terrible model. We are to believe that the impact of the fuselage would have slowed down the wings because the plane can be assumed to be a rigid mass? That's ridiculous. The wings contained the fuel tanks, and they were nearly full. That's where the mass is. On their own momentum, the wings break from the fuselage and continue on toward the building before they are slowed down significantly, or at all.

 

[investigating911]

I'm just a caveman, but this sounds like a terrible model. We are to believe that the impact of the fuselage would have slowed down the wings because the plane can be assumed to be a rigid mass? That's ridiculous. The wings contained the fuel tanks, and they were nearly full. That's where the mass is. On their own momentum, the wings break from the fuselage and continue on toward the building before they are slowed down significantly, or at all.

Well like the window glass is the weak point in a building, the wings are a less sturdy piece of an airplane and the weak point in an airplane (wings seem like the first to shear off an aircraft in any crash or extreme turbulence), so I don't see why it would be unreasonable to assume that if the airplane was traveling at a slower speed, the wings would be sheared off during impact and not fully make it into the building, while the front part of the fuselage would still make it past the exterior columns.

But the momentum and mass of the airplane and the mass of the fuel tanks in the wings might be able to overcome the issue of the airplane impacting the exterior facade at a slower speed, so that even the wings still weaken the connections enough on impact to sever the exterior columns, as @Jeffrey Orling explained.

From what @Oystein explained, it appears that when the buildings were constructed, even a much slower speed would still result in all of the airplane being able to break through and severe the exterior steel facade. I wasn't sure if this was the case before, but from the account of the engineers that he detailed in his post, it appears that this would be the situation, clearing up some of my confusion about what occur had the planes impacted the towers at a slower speed (i.e. a speed typical of the lost in fog and trying to land scenario).

Still, isn't it possible that when the planes impacted the building at a fast speed, some of the debris that fell out of the impacted face consisted of the disintegrated rear and tail end of the airplane?

 

[Edward Current]

Still, isn't it possible that when the planes impacted the building at a fast speed, some of the debris that fell out of the impacted face consisted of the disintegrated rear and tail end of the airplane?

I suppose it's possible, but is there any evidence that this happened? I certainly don't see anything that looks like plane fragments in any of the photos you posted.

Do you think it's reasonable that parts of the back end of the plane stopped in mid-air and fell to the ground? Or bounced off the building? Bounced off what part of the building? There was a giant hole there.

 

[investigating911]

I suppose it's possible, but is there any evidence that this happened? I certainly don't see anything that looks like plane fragments in any of the photos you posted.

The eyewitness account of the tail falling onto Liberty Street (Liberty Street was near the south face of the south tower, and UA175 impacted the southeast part of the south face of the south tower)

It progressed down the building, breaking the windows as it went; the entire building was groaning, an unnatural, unearthly sound, much like a can squeezing, or cracking uncooked spaghetti. By the time it reached the lobby, the marble veneer was cracking and falling off the walls; the chandeliers shattered on the floors along with the plaster ceiling, and the force imploded in at about 50 mph, pulling metal, balled safety glass, and other material with it. The pipes were bursting over my head and dense materials were flying around me as if they were being pureed in a blender. In the next instant came a horrible noise and a flash of extreme heat and light blown directly over my head. I concluded later in the day that this was from the huge airplane fireball sent down the 78-110 elevator shaft that exploded out into the lobby, and blew around the walls and curled into the center vestibule where I was taking cover. The third and last explosion occurred when a huge chunk of burning wreckage fell to Liberty Street, which runs parallel along the south side of the South Tower, and crashed through the building into the lobby behind me, bringing metal, glass, marble and revolving doors with it. There had been four security men and some fleeing WTC workers behind me near those revolving doors; I realized that they were all taken out by either a huge chunk of the building exploding outwards or the tail end of the plane falling to the street. I now know that there were nine of us in the lobby that day when the plane hit, two NYPD officers on the 44-77 elevator side, and two others coming out of emergency stairwells on the 78-110 elevator side. The two officers and I were the only ones who made it out alive.

Text enlarged and underlined for emphasis
source: https://sites.google.com/site/911stories/insidethesouthtower:eyewitnessaccounts

Do you think it's reasonable that parts of the back end of the plane stopped in mid-air and fell to the ground? Or bounced off the building? Bounced off what part of the building? There was a giant hole there.

No, I would think for the most part the momentum of the plane would mean that most of the fuselage, the broken off wings from the fuselage (which nonetheless had enough momentum to continue moving into the tower), the air in the plane (and surrounding heated air) and all but the tail end of the aircraft would end up entering the building and the most of the solid contents making up the airplane remaining in the building, with mainly the heavier parts of the aircraft (like the engines) continuing on to the opposite face, knocking out the columns they impacted on the opposite face, and finally falling to street level below. More morbidly, the lighter contents of the aircraft (such as vests, papers and body parts) would be carried by the remaining impact blast and wind out of the hole on the opposite side of the tower and also fall to the ground or roofs of nearby shorter buildings.

Upon second examination given the details provided by others in this thread about how the wings would definitely penetrate the exterior columns, it's likely that a lot of what appears to be the falling aluminum from the impacted face is the tower's exterior aluminum cladding, and not the aluminum of the airplane.

I thought that some of the rear end of the aircraft would explode out of the impacted face and onto street level because of seeing photos of body parts on Liberty Street, but it's possible that's mostly from the impacts of the plane into the north tower earlier, as although the south tower was offset from the north tower, the wind would blow those body parts to the southeast, with some of it falling at the entrance of the south tower and the Deutsche Bank buildling entrance, possibly with flaming debris lighting some cars in the Liberty Street parking lot (near the St. Nicholas Greek Orthodox Church) on fire.

 

[JMartJr]

Well like the window glass is the weak point in a building, the wings are a less sturdy piece of an airplane and the weak point in an airplane

Can you cite a source for that? My understanding has always been that the wings are among the strongest parts of a plane, for obvious reasons when you consider the consequences of wing failure while flying along! I'm also unsure why the wings shearing off in this scenario would make them less likely to penetrate the buildng -- they are still moving forward towards the building, are still very heavy being filled with fuel and would now be free of any deceleration the fuselage is experiencing, being no longer attached to the fuselage.

 

[investigating911]

Can you cite a source for that? My understanding has always been that the wings are among the strongest parts of a plane, for obvious reasons when you consider the consequences of wing failure while flying along!

I don't have a source. On their owns the wings with full fuel tanks are robust enough, but they are still fairly narrow in width compared to the fuselage. I would think that this along with the fact that the wings are attached to the fuselage by connections would mean that the wings are some of the easiest parts to come loose on an airplane.

If the wings are the strongest parts of the plane, why is it that they are often the first to detach from the fuselage in any severe turbulence, rough landing or plane crash?

I'm also unsure why the wings shearing off in this scenario would make them less likely to penetrate the buildng -- they are still moving forward towards the building, are still very heavy being filled with fuel and would now be free of any deceleration the fuselage is experiencing, being no longer attached to the fuselage.

I would think that even though the wings are moving forward and have forward momentum into the building, in a scenario where the plane is traveling at a signficantly slower speed than the planes that crashed into the towers (the plane lost in fog and looking to land scenario), the wings (being sheared from the plane) would have lateral movement to the side from the beginning explosions as much as forward movement into the building, meaning at lower speeds like the lost in fog scenario, there would be parts of the main body of the wing that didn't enter the building at all and fell to street level below to the base of the impacted face.

 

[Mendel]

the wings are among the strongest parts of a plane

A321 wing tip after hitting a runway sign on takeoff (they got airborne and landed safely).

Article:

Source: https://avherald.com/h?article=4c68c5a8

The 737 that was shot down by Iran on Jan 8, 2020 kept flying after a missile strike:

Article:

The air defense's launching two surface-to-air missiles at the flight PS752, UR-PSR aircraft, the detonation of the first missile warhead in proximity of the aircraft caused damage to the aircraft systems, and the intensification of damage led the aircraft to crash into the ground and explode instantly.​

Source: https://avherald.com/h?article=4d1aea51/0000

Aircraft are tough.

 

[Mendel]

If the wings are the strongest parts of the plane, why is it that they are often the first to detach from the fuselage in any severe turbulence, rough landing or plane crash?

Because of the leverage brought to bear on the wing root when the wing is impacted in a crash.

Severe turbulence or rough landings do not detach wings.

Note the wings did not come off.

 

[investigating911]

Because of the leverage brought to bear on the wing root when the wing is impacted in a crash.

So wouldn't it follow that in a lower speed plane crash (like was envisioned when the towers were originally constructed), at least a significant portion of the wings farther away radially from the fuselage would be sheared off and not enter the building?

Severe turbulence or rough landings do not detach wings.
View attachment 47248
Note the wings did not come off.

I can't really see the wings in that picture as they appear to be submerged under the water.
One-sided rough landings (where the plane is tilted enough that the wing touches or just touches the ground) do seem to sometimes be enough for the wing to easily dettach though. The rough landing in the Hudson River appears to be while the airplane was horizontally oriented but skidding into the water, so that the complete underside base of the wings impacted the water first, rather than a portion of the wing at a steep angle.

The planes hit the towers tilted but head on, but not with the broad width underside of the wings impacting first but instead the narrow width front sides of the wings.

 

[Mendel]

I would think that this along with the fact that the wings are attached to the fuselage by connections would mean that the wings are some of the easiest parts to come loose on an airplane.

On an aircraft with wing-mounted engines, these connections are strong enough to allow the engines to quickly accelerate the fully loaded fuselage to take-off speed.

The 767 wing attaches over ~20% of the length of the fuselage. You'll be hard pressed to find a household item with a bigger handle.

Article:

Source: http://jaesan-aero.blogspot.com/2019/04/comparison-of-airliners-wing-plan-form.html?m=1

 

[Mendel]

I can't really see the wings in that picture

I assure you they're there.
This was a "rough landing".