# How high could the plane have hit, and still caused a total collapse?

How the collapse initiates affects how much it can destroy what's below… The important part being how much speed it picks up before meeting significant resistance, ie impacting the lower sections.
Nope. A structure can be destroyed solely because of the load that is upon it, not because of the speed at which the load lands upon it. Even 4-year-olds are familiar with this concept, apparently: https://en.wikipedia.org/wiki/Buckaroo!
(Milton Bradley Games' "Buckaroo")

Yes. Reread my first post again. Try to understand the difference the pencils make.
Do you mean this one?
It's not the tiles breaking the tiles, it's the human.
Don't we just completely agree? Namely, that
the energy to destroy the tower comes from the body of the person impacting the top block.

Do you mean this one?

FatPhil said:
It's not the tiles breaking the tiles, it's the human.

Don't we just completely agree? Namely, that

Thomas B said:
the energy to destroy the tower comes from the body of the person impacting the top block.

No, they literally couldn't be more different.
In mine, the human is *continually pumping energy into the system by following through the whole way*.
In yours, he's only "impacting the top block".

No, they literally couldn't be more different.
In mine, the human is *continually pumping energy into the system by following through the whole way*.
In yours, he's only "impacting the top block".
Ah, I see. I was being imprecise and you are right. My point was only that if you're going to propose a model that looks like the WTC collapses you need *all* the energy to come from (potential stored) inside the initial state of the system. Your point is more subtle, and I have no issue with it.

Why all these derails into irrelevant and non-analogous evasions? Let's try to get back onto the topic.

The OP Topic is:

### " How high could the plane have hit, and still caused a total collapse?"

Total collapse of the WTC Towers - NOT some Verinage which is not an analogue of WTC collapses. Not some Karate Trick which is not analogous.

The OP question has already been answered. And the answer depends on understanding ONE simple fact.

Both the WTC Twin Towers collapsed TOTALLY because the falling debris missed the columns as per this diagram posted several times previously and which has been consistently ignored by members:

For the WTC Twin Towers the falling debris MISSED the columns of the Lower Tower. IF the top block had impacted with the columns aligned the progressive collapse:
(a) Would have halted >> which is the consensus of informed on-line discussion and of relevant published papers; OR
(b) It MAY have still progressed - a possible and insightful hypothesis posted earlier in the thread by @Mendel. I agree with his point and the suggestion has not been discussed to resolution.
The thing with these verinage demolitions is they're started near the middle, and the top block is used to destroy an equivalent number of floors as are in the top block. You will not find a video of a verinage demolition where the top 10% is used to destroy the lower 90%.
So what? Despite your reluctance to comprehend the actual mechanism, the WTC Twin Towers did in fact collapse as a consequence if a small upper portion shearing floors off the larger lower tower. It did happen, false analogies by verinage examples or Karate tricks set aside. And the actual mechanisms of WTC Twin Towers collapses have been fully explained.

It's hard to imagine that cutting off the top 6-10% of such a structure and dropping it a few feet onto the rest of it would be enough to raze it to the ground.
For the WTC Twin Towers here is no need to "imagine". It did happen. All that is needed is an explanation of how. And that explanation has been available, posted on line, since 2007 AND repeated in this thread.
The way to get people to imagine it is to describe a simpler structure, with fewer columns and fewer floor-to-column connections that is very, very strong (for its weight), and then show how the movement of that top section down through the structure breaks it up into tiny pieces.
Utter nonsense. The actual WTC collapses are clearly accessible in the video record. The barrier to understanding is in the resistance of some members who choose to not see the obvious.
Also: it will be useful to show that (and why) less than 5% wouldn't do it.
OR "would do it". Yes. And both options were identified way back in this thread before all the derailing and side tracking took over. Again.
That is, a smaller top section would behave as the person who has a hard time understanding the collapses would expect.
The actual challenge is to understand what really happened and that is not difficult.

One final comment:
By the way, here is John Gross of NIST categorically saying they did not do any calculations on why the collapse wasn't arrested by the lower floors:
Of course there were no need for calculations. It is obvious to anyone who understands the simple mechanism that progression, once started, would be unstoppable. There is no need for "sums" to prove it. The difficult part to explain is how it was started. But there is no doubt that it did start.

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The floor connections are designed to hold up a single floor, plus a safety margin. They do not get sturdier lower down. If you can rip off a floor at the top with the weight of the debris, you can rip off a floor at the bottom.

Continuing my theme: "Let's try to get back onto the topic."
I think the collapse would have been initiated by impacts higher than those on 9/11. For this post, I won't attempt to guess "How much higher?"

There are two critical factors - and comprehending them requires an understanding of the actual collapse mechanisms. What actually happened on 9/11.

The first critical factor is how much superimposed load is required to trigger the "initiation stage" and "drop" the "Top Block". That aspect is hard to "ballpark" quantify. For the real event the ~11 storeys Top Block of WTC1 was sufficient to provide the necessary weight in the right places. Let's leave that aspect for now - there are two ways forward viz qualified assessment with some ball park guesses OR more detailed quantification. And I doubt that the detailed quantification path is practical. With anything less than a major study analysis.

The second critical issue is - once the Top Block starts to fall will the collapse go into unstoppable progression. That one is easily answered "YES" - again provided you understand the progression mechanism of the "real event". Explanation later when required.

So, yes, in my opinion, impact at a higher level could have initiated a collapse. I cannot at this time guess how much higher. I'm sure that, once the "Top Blck" dropped it could not be arrested and global collapse would ensue.

So of the two factors I identified - triggering the initiation is the one that is key.

you are still thinking in terms of kinetic energy, this is wrong
think in terms of weight
if you put too much weight on a structure, it breaks
it doesn't matter much if you decelerate it first
the weight that breaks floor 72 also breaks floor 71
rather, it breaks the connections that attach it to the sturdy vertical columns
[it also breaks the floor, but all we are concerned about is that it comes loose)
Nope. A structure can be destroyed solely because of the load that is upon it, not because of the speed at which the load lands upon it. Even 4-year-olds are familiar with this concept, apparently: https://en.wikipedia.org/wiki/Buckaroo!
(Milton Bradley Games' "Buckaroo")
The tower had held the weight of the top block just fine for decades, and the plane impact didn't increase that weight. The only reason there would be any substantial collapse at all would be if the top block started to drop, like a verinage demolition, and then impacted the lower section… This would cause an amplified load much greater than its weight. Similar to dropping an anvil on your foot rather than slowly setting it on your foot. An amplified load requires a deceleration, though.

The tower had held the weight of the top block just fine for decades, and the plane impact didn't increase that weight. The only reason there would be any substantial collapse at all would be if the top block started to drop, like a verinage demolition, and then impacted the lower section… This would cause an amplified load much greater than its weight. Similar to dropping an anvil on your foot rather than slowly setting it on your foot. An amplified load requires a deceleration, though.

How many more trips around the same logical circle will this take?

Obviously, reducing a structure's ability to support can have the same effect as amplifying the load on it. This is not complicated. And that's just the initiation. For the progression, of course none of the floor systems was supporting the floor systems above it at any time prior to the collapse. That's a clear increase in weight, to say nothing of the massive forces exerted by that weight when falling, so, even by your own conspicuously half-blind logic, you should now be able to understand that much at least.

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Of course there were no need for calculations. It is obvious to anyone who understands the simple mechanism that progression, once started, would be unstoppable. There is no need for "sums" to prove it. The difficult part to explain is how it was started. But there is no doubt that it did start.
It's not always unstoppable, though:

Source: https://www.youtube.com/watch?v=Q0ZtqqBsAs8

Furthermore, if it's so "obvious", then presumably those calculations would be pretty simple and wouldn't take much time. So why not just do them?

It's not always unstoppable, though:
@Henkka it is becoming very clear that you are not serious.

I have made many posts patiently explaining the relevant issues involved in the discussion of YOUR OP for this thread. Also addressing the derails that have occurred.

The progressive collapses of BOTH WTC Twin towers were unstoppable. And THAT truth is obvious by observation to any sufficiently competent person who understands the mechanism of the progression stage of the WTC Twin Towers collapses.

I have repeatedly advised you to understand the actual mechanisms of WTC collapses. You persist in ignoring both my advice and the explantions I post.

So why do you present a silly disagreement based on a different collapse of a different building?

The progressive collapse of the WTC Twin Towers, once started , was unstoppable! << IF you want to disagree with THAT statemnt present yuor reasoned arguments. IF you don't understand why it was unstoppable - ask and I will outline the reasons.
Furthermore, if it's so "obvious", then presumably those calculations would be pretty simple and wouldn't take much time. So why not just do them?
1 plus 1 equals 2 doesn't need explaining.

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The tower had held the weight of the top block just fine for decades, and the plane impact didn't increase that weight.
1. The weight was held by columns.
2. Some columns were damaged/destroyed by the impact.
3. Some columns and trusses were weakened from heat.
4. NIST showed that this reduced the load capacity of the structure so much that it failed.
5. The structure became unable to support the top block, because of 4.
6. The top block fell on a floor below, increasing its load.
7. The floor became overloaded, detached from the columns, and fell.
8. The debris fell onto the floor below that.
9. The floor became overloaded, detached from the columns, and fell.
10. The debris fell onto the floor below that.
11. The floor became overloaded, detached from the columns, and fell.
12. The debris fell onto the floor below that.
13. The floor became overloaded, detached from the columns, and fell.
14. The debris fell onto the floor below that.
15. Repeat all the way to the bottom.

This left the facade and much of the core standing, but unbraced, and the pertubations of the debris avalanche caused those columns to fall as well in short order.

tl;dr the impact & the fires destabilised the top block, the weight of the top block then overloaded the floors in turn.

It's not always unstoppable, though:
Was this building a hollow tube with open-plan office space? No? There you go different structure, different situation.
View attachment 52480
this photo was taken during construction.
Do you see in this picture that, apart from the central cores, this tower is hollow?
Your stoppable collapse does not look like this.

Furthermore, if it's so "obvious", then presumably those calculations would be pretty simple and wouldn't take much time. So why not just do them?
Was done, NIST FAQ #18.

@Henkka, you keep asking the same questions over and over, please rethink your approach. What are your goals with respect to this discussion?

So why do you present a silly disagreement based on a different collapse of a different building?
Well, there's never going to be a 1:1 comparison because I can't build an exact replica of the North Tower and fly a plane into it to see what happens. And since the entirety of engineering acamedia seems uninterested in doing computer simulations of this event, what else can you do but compare it to other buildings? To that end, I think videos of failed demolitions are interesting, since they show that even deliberately engineered collapses can sometimes stop halfway. You can go on Youtube to find many such videos. But in the case of the three WTC towers, you would have to believe that random processes like fire did a better job in demolishing these buildings, and there's no way the collapses could have stopped.
Was this building a hollow tube with open-plan office space? No? There you go different structure, different situation.
Was the core of the WTC towers a hollow tube?

Was the core of the WTC towers a hollow tube?

Irrelevant - it wasn't the core that underwent progressive collapse.

To that end, I think videos of failed demolitions are interesting, since they show that even deliberately engineered collapses can sometimes stop halfway.
How does this connect logically to the WTC collapse?

Sometimes, demolitions work and sometimes they fail.
Sometimes burning steel frame buildings collapse, sometimes they don't.

How does that tell us anything?

But in the case of the three WTC towers, you would have to believe that random processes like fire did a better job in demolishing these buildings
Do you think a random process cannot demolish a building?

If a demolition destroys a building almost every time, and a fire rarely does, does this mean fire does a better job at demolishing buildings than humans do?

Was the core of the WTC towers a hollow tube?
Who claimed that it was?

Consider this picture (click to enlarge):
View attachment 52480
Which part of the building looks hollow to you?
a) the core
b) everything inside the outer walls except for the core?

And since the entirety of engineering acamedia seems uninterested in doing computer simulations of this event,
Why, do you think, are they not interested?

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Anyone with a basic understanding of structure knows that components of a building... floor (systems)... axial systems (columns) framing systems... etc have structural strength limits. Engineering use the strength properties of materials to design structures.
It is settled knowledge that when loads exceed design capacity... a failure will occur... and that can lead to a local and even a global collapse.
The column free floors were structurally identical and if a floor failed it would collapse on to the on below. A typical floor could support a static load or perhaps 3x the weight of a single floor. If a load exceeds the limit the floor will fail/collapse and fall on to the one below where it too will fail and the process will repeat all the way to the bottom.
Columns were not involved and could not prevent a floor collapse. The columns, however, depended on the floor plates for lateral bracing/support. And once the floors were "gone" the unbraced columns were too unstable to self support and they buckled... final phase of the total building collapse. This is settled known engineering.
The initial floor collapse (which went runaway) was the result of the frame failing locally from excessive heat. This was likely the result of beams, girders (lateral steel members) expanding and pushing columns out of axial alignment to the point where they buckled... and that led to what they supported dropping free.... until it encountered the floor a slab/plate destroying it and causing the runway progress rapid collapse of the floors top to bottom (pancaking).

Who claimed that it was?

Consider this picture (click to enlarge):
View attachment 52480
Which part of the building looks hollow to you?
a) the core
b) everything inside the outer walls except for the core?
All buildings are "hollow" because they are usually more than 90% air.

Anyone with a basic understanding of structure knows that components of a building... floor (systems)... axial systems (columns) framing systems... etc have structural strength limits.
Henkka knows this. Telling it again isn't going to help them think about it.

All buildings are "hollow" because they are usually more than 90% air.
Yet in some buildings, before furniture is installed, you can run around blindfolded almost safely, while in others you're more likely to quickly run out of air and collide with something hard (not air). In that sense, the WTC is exceptionally hollow.

The load-bearing elements of the WTC form a hollow tube with a central core.
In most other large buildings, they form a grid or a lattice.

Henkka knows this. Telling it again isn't going to help them think about it.

Yet in some buildings, before furniture is installed, you can run around blindfolded almost safely, while in others you're more likely to quickly run out of air and collide with something hard (not air). In that sense, the WTC is exceptionally hollow.
BUILDINGS are essentially 90% air and then they are filled up with "contents" people, equipment, furniture, stored materials - "things". A "building" like a pyramid is essentially solid with only passages within it.

You can go on Youtube to find many such videos. But in the case of the three WTC towers, you would have to believe that random processes like fire did a better job in demolishing these buildings, and there's no way the collapses could have stopped.
And you think formulas/calculations are going to help you understand this better than people here in this forum describing and illustrating the mechanics/processes that caused total collapse? How? Do you need formulas and calculations to believe/understand how planes fly?
Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing. The difference in pressure creates a force on the wing that lifts the wing up into the air.

Take a look again (if you even did in the first place) at econ41's post #167. Do you understand the mechanic/process he explains therein? Do you understand what the picture shows?

I personally believe both you and Thomas B are truthers and are trying to hide that fact by the "trying to understand what happened" and "just asking questions" facades. You're talking points and arguments at this point wreak of "trutherisms".

Irrelevant - it wasn't the core that underwent progressive collapse.
So why didn't the core behave like the failed demolition I posted?
@Henkka, you keep asking the same questions over and over, please rethink your approach. What are your goals with respect to this discussion?
Well, my overall goal in creating an account here was just to discuss the WTC collapses. Obviously I'm coming from a point of view where I'm pretty skeptical of the official explanations. It's a rabbit hole I started going down maybe like a year ago, and I found the arguments made by people like David Chandler pretty persuasive. I've gotten into discussion about this before with people on Reddit, but the problem there is that whoever I got into an argument with was usually not that informed about the topic. It felt like people would just type "wtc conspiracy debunked" into Google and copy whatever they found back at me. So I thought creating an account here would be interesting, to see what people would say about some stuff I had been thinking about, like the topic of this thread of how high the plane could've hit and still caused a total collapse. The consensus here seems to be yes, the plane could have hit even higher, with the minimum to cause a total collapse being six floors. Like I'm sorry, but I find that pretty unbelievable... That such a thin slice of the building could reduce the 100+ floors below into a pile of rubble. Combined with other anomalies like the unprecedented collapse of WTC 7, I still find the entirety of the 9/11 event to be suspicious in the extreme. I do agree though that some of these conversations are just going around in circles.

And you think formulas/calculations are going to help you understand this better than people here in this forum describing and illustrating the mechanics/processes that caused total collapse? How? Do you need formulas and calculations to believe/understand how planes fly?

Take a look again (if you even did in the first place) at econ41's post #167. Do you understand the mechanic/process he explains therein? Do you understand what the picture shows?

I personally believe both you and Thomas B are truthers and are trying to hide that fact by the "trying to understand what happened" and "just asking questions" facades. You're talking points and arguments at this point wreak of "trutherisms".
Labels.... It's possible for a confused person... ie one who doesn't have a technical background or know much about the details of the collapses could ask questions in an attempt to understand. Truthers are essentially "deniers"... science deniers who essentially have a "political agenda" which amounts to the media and the authorities are lying/deceiving the public to conceal some "insider plot".
The actual "explanation"... fanatics hijacked planes in suicide missions to make a political statement (the great satan is vulnerable)... and the collapses were consistent with engineering, physics/science doesn't fit with their underlying conspiratorial view of the world. Truthers need to remove the (political) filters which prevent them from understanding. Gage, for example, has gone on to be an anti vaxxer for the same reason... if authorities say it... it's a lie and covering up some nefarious fact. These sorts of people are not interested in facts or truth.... but rather confirmation of their bias. It should be noted that groups like AE911T fog the debate with bogus "arguments" which appear to be sound engineering/science. They are not. Unfortunately naive people can't tell and are deceived. So many idiots and so little time.

So why didn't the core behave like the failed demolition I posted?
Because it collapsed like both WTC Twin Towers AND "we" - or at least "I" - can explain if ever you decide to take my advice and understand the collapses of the WTC Towers NOT any other building whether it did or did not collapse.
I found the arguments made by people like David Chandler pretty persuasive.
Then post any one of David Chandler's claims in its own thread and I will explain why he is wrong and what the correct explanation is. (AFAIK he is right on ONE topic - it was a plane that impacted Pentagon.)
The consensus here seems to be yes, the plane could have hit even higher, with the minimum to cause a total collapse being six floors. Like I'm sorry, but I find that pretty unbelievable...
Then stop playing games and get serious. Decide to learn - remember that was your intention stated in the OP.

I do agree though that some of these conversations are just going around in circles.
The ball is in your court to avoid circling.

And you think formulas/calculations are going to help you understand this better than people here in this forum describing and illustrating the mechanics/processes that caused total collapse? How? Do you need formulas and calculations to believe/understand how planes fly?
I guess not, but I know for a fact that such calculations exist and have existed for over a hundred years. With the WTC collapses, we have John Gross saying NIST didn't do calculations on why the collapse wasn't arrested, and Bazant's calculations which are so sketchy that not even people here believe he got it right.
I personally believe both you and Thomas B are truthers and are trying to hide that fact by the "trying to understand what happened" and "just asking questions" facades. You're talking points and arguments at this point wreak of "trutherisms".
What my current conclusion about the event currently is is irrelevant imo... I think you can discuss this stuff without dividing into the camps of "truthers" and "debunkers". But I don't think I'm exactly hiding the ball that I think it's possible, or even probable, that all three buildings were deliberately blown up.

So why didn't the core behave like the failed demolition I posted?

.......The consensus here seems to be yes, the plane could have hit even higher, with the minimum to cause a total collapse being six floors. Like I'm sorry, but I find that pretty unbelievable... That such a thin slice of the building could reduce the 100+ floors below into a pile of rubble. Combined with other anomalies like the unprecedented collapse of WTC 7, I still find the entirety of the 9/11 event to be suspicious in the extreme. I do agree though that some of these conversations are just going around in circles.

Your ignorance of engineering, basic physics and lack of critical thinking helps you down the rabbit holes.

FACT
any floor in any building has a structural load limit. If that limit is exceeded (overloaded).... the floor fails and collapses.
The twin tower collapse were the result of the top blocks losing support (initiation phase) and those blocks were more than enough mass to destroy ANY floor in any building.

7WTC collapse was the result of a steel frame building burning for 7 or more hours without fire fighting. It is settled engineering that steel frames must be protected from fire.... and they are designed with 2 or 3 hour fire protection. Sprinklers failed. It is completely consistent with fire science/engineering that the frame would fail.
The FORM of the collapse was related to the structural design which had to support a 40 story building built over a substation. The failure of numerous transfer structures (required to build over the substation) essentially were "responsible" for the failure propagating through out the structure.

It was a progressive, runaway failure of a complex (structure) system.

https://how.complexsystems.fail/

There was no "mechanism" to arrest the failure once underway.

I guess not, but I know for a fact that such calculations exist and have existed for over a hundred years. With the WTC collapses, we have John Gross saying NIST didn't do calculations on why the collapse wasn't arrested, and Bazant's calculations which are so sketchy that not even people here believe he got it right.

What my current conclusion about the event currently is is irrelevant imo... I think you can discuss this stuff without dividing into the camps of "truthers" and "debunkers". But I don't think I'm exactly hiding the ball that I think it's possible, or even probable, that all three buildings were deliberately blown up.
Why did you leave out the part of my quote where I asked if you understood the mechanics/processes explained in econ41's post #167?

Again, do you understand what was explained?

I guess not, but I know for a fact that such calculations exist and have existed for over a hundred years. With the WTC collapses, we have John Gross saying NIST didn't do calculations on why the collapse wasn't arrested, and Bazant's calculations which are so sketchy that not even people here believe he got it right.

What my current conclusion about the event currently is is irrelevant imo... I think you can discuss this stuff without dividing into the camps of "truthers" and "debunkers". But I don't think I'm exactly hiding the ball that I think it's possible, or even probable, that all three buildings were deliberately blown up.
YOU are a denier of science/engineering and prefer to believe in "magic".
The math explaining the collapse is trivial... basic engineering...

The initiation "released" mass which was directed by the structure to the foundation. The released mass was MORE than enough to overwhelm any floor it fell upon. HEAT was the proximate cause of why the mass was "released" (freed from the structure).

So why didn't the core behave like the failed demolition I posted?

Because the core is absolutely nothing like the building the in failed demolition you posted.

I guess not, but I know for a fact that such calculations exist and have existed for over a hundred years.
And load calculations for floors, connections, structural components, etc. DON'T exist?

Do you need calculations to understand econ41's illustration in post #167 to understand how floors were overloaded which cased them to fail?

Do you need calculations to understand why the 6 floors impacting the first intact floor below destroyed said floor and then the descending rubble pile became 7 floors worth of debris to impact the next floor, etc., etc.

FWIW... We're dealing with willfully ignorant people. Explanations (correct ones) on every level of expertise from rank novice to engineering professional have appeared in numerous online discussions / sites over the years. People like Gage have had years to "familiarize" themselves with the science/physics and engineering explaining why/how the buildings collapsed. Understanding does not require calculations or formulas. YES engineers use these to DESIGN "anything"... that's a design tool.

Everyone understands that if you stand on a wine glass it will shatter. No formulas needed. Sure one could provide a calculation showing your weight (superimposed load) on the glass's "load bearing" specification... and collapse would be obvious.

It may not be obvious that a typical twin tower floor could support X pounds per square foot... And it hardly matters... the floors were designed for the anticipated loads (with a factor). The safety factor was far exceeded.... so failure of the floor slabs was inevitable.

People are confused by the role of the columns and why they didn't prevent collapse. The collapse was failure of the slabs themselves and the connections of the slabs to the columns... Columns were actually "unloaded" when the floors broke free and collapsed. Columns failed because their stability was provided by the floor plates. When the floor plates were no more the columns became unstable and collapsed. (a radio antenna will collapse if the guy wires (bracing) are removed. Bracing provides stability and strength to a structure. Columns support floors. Floors brace columns (in the case of the twin towers) Not buildings with a rigid grid/lattice frame rely on the frame not the floor plates. But floor plates provide "bracing" for a frame.

So why didn't the core behave like the failed demolition I posted?
How do you know it didn't?

Are you clear what "the core" means with respect to the WTC?
View attachment 52480

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Well, my overall goal in creating an account here was just to discuss the WTC collapses.
What is a good discussion like for you? How is it different from a bad discussion?

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