@ various:
I've seen some reasoning here, which seems particularly at risk to lead to invalid conclusions.
The implicit premise, is that the Presumed Bad Guys are Really Clever and Highly Capable. Therefore, the way an attack played out in detail, is a reflection of Bad Guy planning and decision-making.
I think there is good evidence that in practice, people who commit such depraved acts are not especially clever, or capable. What perhaps sets them apart, is that they are really determined to do things most people would never choose to do.
Example 1: The "Bomb Trigger"
There's been much discussion (in this and the previous thread) about barometrics, timers, consumer electronic devices, etc. I wish to observe that the effect of triggering several minutes AFTER the cabin reaches its maximum pressure altitude, could be achieved by a really crude home-made trigger that by design should have worked earlier, but introduced a delay by accident.
What I'd like to remind folks of, is that it's quite possible there was a really sophisticated trigger; we don't know. It's also quite possible there was a stupid-simple trigger; we don't know. On the basis of publicly available information, we Just Don't Know.
Example 2: Killing the Black Boxes
Terrorists are inherently opportunistic: their attacks are shaped by openings and weaknesses in defenses against them. For this reason, some aspects of such attacks are quite intentional (for example, the type of targets); but others are quite accidental (this target was easier to get to).
Did someone
really decide to design their attack, to disable the flight recorders?
If so, WHY? Do we really imagine terrorists sitting around a table saying, "there are some things about our attack we want to keep secret after the plane is destroyed, that MIGHT leak out from the flight recorders. Therefore, we must disable them!" REALLY??????
Did they plant a bomb aft because they concluded that this position was most likely to doom the aircraft?
Did they plant a bomb aft because they expected that this position would be easy for them to access, with a lesser risk of getting caught?
Or maybe, just maybe ...
did they stick it under a rear seat, because passengers don't put stuff under seats in the last row?
________________________
Dear armchair investigators, let me remind you of the
principle of least hypothesis.
Let me also remind you (as I believe somebody did on the big thread), Usama bin Laden is on record as saying he did not expect the twin towers to collapse. From his point of view, the cataclysmic scale of devastation was
pure dumb luck -- the most elaborately planned terror attack the world has yet seen, made its most terrible effect by accident, not design.
Of course, we are all free to wander out onto
the Grassy Knoll ... but let's remember that we are much more likely to find our own fantasies there, than anything that actually happened.