In the minutes following the attacks, it would also not have been clear that these were two planes fully loaded with fuel for a trans-continental flight. Especially the first one - the fire, from the camera angles I saw, looked bad but not necessarily out of control. The second one, of course, with the enormous fireball and (later) fire obviously creeping down the structure - well, even then, what the article says wouldn't have been blindingly obvious.

But the towers' ultimate collapse was inevitable, as the steel cores inside them reached temperatures of 800C - raising questions as to why hundreds of rescue workers were sent into the doomed buildings to their deaths.

How many of these firemen were structural engineers? How many of the policemen were structural engineers? How many of the people on the scene knew much about the actual construction of the building? Did they have experts in steel core design buildings on the scene? Did they have the original architect and/or construction managers on the scene?

Nobody expected the building to collapse. What is so damned obvious to Professor Knapton doesn't seem to have been obvious to anyone at the scene.

If it was obvious to Professor Knapton, where was he when the firemen and police were sent in? Oh, that's right, he's a professor of structural engineering at Newcastle University, UK - they didn't have the benefit of his sage advice anyway.

And, in any case, even if warned the buildings were "inevitably" going to collapse in a couple of hours, I think you're right - they would have gone in anyway.

I'm sure they knew about the special sheathed construction of the towers. They probably also knew that the towers had been build to withstand the impact of a jet plane - and, at the time, it would not have been clear what size or type the planes that rammed the towers were. Add to that the fact that the towerrs were still standing after the impacts - aha! the towers were living up to specifications.

What nobody seems to have known or anticipated was that the fire would be so hot that the steel would melt. Again, nobody anticipated the collapses. It takes some expert from England to analyze the "obvious" and "inevitable" danger of collapse for us?

As much as they might have had refresher courses and had high-rise fighting training and known the peculiarities of all the major structures in the area, I don't think they or, apparently, any one except this professor in England had any clue it might collapse.

Isn't one aspect of firefighter training an emphesis to take no unnecessary risks? If you're dead, you can't help anyone. Of course firefighters take risks every time they answer an alarm. They take risks just driving down the street trying to get there, and horrendous risks in fighting the fires. But they're calculated risks, not suicidal risks. Or so I've been told.

I still believe they had no idea the towers would or could collapse. I've seen the videos of firefighters fighting ordinary fires in ordinary houses - when the thing is about to collapse, they do pull back, don't they?