Oystein
Penultimate Amazing
- Joined
- Dec 9, 2009
- Messages
- 18,941
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...Some of the issues that come to my mind:
1. Probably would have pilot alerts going off (audio warnings, blinking lights, etc.), causing distractions to the pilot. This creates a higher workload, increasing the likelihood of getting behind in the primary task of hitting the building. If the pilot gets behind, the deviations from some nominal flight path become larger, and the need to correct the deviations become more time critical.
2. The need to correct deviations is where the increased closure rate, and need for faster reaction times is where I would expect the greatest problems.
3. Since the plane is flying well beyond the design limits, I wonder at the primary control surfaces power actuators ability to respond to the pilot’s more abrupt commands (which would be coming if the deviations from nominal became quite large.) Can the hinge moments possibly demanded by the pilot’s commands be met by the power actuators (which were designed under the assumption the plane would not be flown that far beyond its design limits.)
4. Is there what traditionally has been called a pilot induced oscillation (PIO) possibility? This is where the pilot’s commands, usually to correct a deviation, couple with the airplane such that the airplane at first seems slow in responding, but then overshoots. The pilot then commands in the opposite direction which becomes out of sync, and an oscillation grows in amplitude, with the pilot inadvertently driving it. This can happen even to an experienced pilot when well outside the design envelope, in that the flight condition would not have been anticipated by the control system and airframe designers.
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A lot depends on how precisely the targets were intended to be struck. I believe the precision desired was much greater than apparently you believe. We can’t resolve that easily, since it deals with intent.
Dadeets,
while I agree that all the points you raise may jeapordize the task the hijacker-pilots set out to accomplish, you word them all in speculative terms. if we were looking at the problem ex ante, your objections certainly would carry some weight and convince me to apply cautious values when assessing the terrorists' chances of hitting the towers with oversped planes.
However, we are looking at the problem from an ex-post point of view, where all probability terms must be factored with a Baysean term expressing the fact that the towers were indeed hit by oversped planes. If, ex ante, the chance of missing the towers was, say, 99%, that chance drops considerably if ex post we already know that the towers were hit and not missed. Then suddenly, the however slim ex ante probabilities don't matter anymore. My father once won the lottery jackpot. It was, ex ante, exceedingly unlikely. But he did win - and that fact does not allow you to conclude that he somehow cheated, because the probability of winning the lottery jackpot is 100%, if you already know that you won it.
You may still wonder, but face it: The identity of the planes is in no serious doubt, and way too many people knew too well the technical shape these planes were in. At the end of 9/11, there were four planes in the service of US-based airlines unaccounted for. You have the airlines, Boeing, the NTSB, the insurances, the FBI, the FAA, the air force, caterers, mechanics, plane spotters, the relatives of passengers and crew all agreeing that indeed the people and material lost on 4 commercial flights that day coincide with witness sightings, DNA readings and debris parts found in the rubble of 4 terrorist attacks.
No matter how unlikely the maneuvers, they were done. You'd have to show they are absolutely impossible to make a case. But you can't and don't do that. You are dealing in felt probabilities, rules of thumb and speculation.