I've spent literally thousands of hours on Boeing flight decks. I know Boeings. In fact...if it ain't Boeing, I ain't going!

I submit the following observations for discussion:

1. The CVR transcript released in the Moussaui trial says something about a "Green Knob." Hmmmmm......Can someone please tell me what green knob the "terrorists" are referring to? The only green on a flight deck are indications of system status. Specifically, for example, on the 757, the stabilizer trim indication is green. As are some indications on the display just forward of the throttle quadrant on the instrument panel. There are many other green indications but no knobs. Green indicates normal, amber indicates caution or a valve in transit, etc. and red indicates you should stop think and evaluate. Then do something in fairly short order. There is blue also, I guess which I believe indicates a valve position. I could be wrong but in all my years flying and maintaing aircraft, I've yet to see a green knob on a flight deck. One last byte on that: some old school diluter demand oxygen systems have a green lever, but a knob? Never heard of such a thing. Please someone correct me on this if I am wrong so I can sleep better at night.

2. Also mentioned in the transcript is something to the effect of "cut off the oxygen." Again, supposedly from the terrorist(s). That one puzzles me. An airplane is a pressurized vessel which relies on what are called packs (2 on the 757), left and right. Both packs receive pre-cooled bleed air from the powerplants and pump it into the cabin. Outflow valves open and close according to psid, or, cabin differetial pressure. I believe the 757 is like most other airliners in that the differential is ~8.6psi. The air is "replaced" about every 6 minutes or so but don't quote me on that figure. The result is the cabin altitude is maintained at about 8000 feet MSL to extend the service life of the airframe. But I don't want to get too deep here right now. Oxygen is controlled on the 757 by a red guarded swith on the overhead panel. The two selectable positions are "ON" and "NORMAL." The oxygen is always "ON." There is a momentary switch right next to it which is for manually releasing the familiar yellow rebreather masks in the main cabin. While there is a circuit breaker for the system, the only thing that does is disable the switch so the masks can't be manually deployed. Normally, the masks are deployed by pressure differential in the atmosphere. Hence, in the event of a rapid or explosive depressurization, they will automatically fall from the compartment abobe the seats (assuming your lungs haven't exploded you can partake). All this leads me to wonder if the terrorists were planning to raise the cabin altitude to their current flight level, thereby reducing the time of useful consciousness to ~30 seconds (FL350). They would pass out too. Besides, I believe the maximum rate of climb for the cabin is ~2000 feet per minute in the manual mode. There is some question about that, though, as that is the extent of the cabin rate of climb indicator. Assuming the airplane eventually reached a cabin altitude high enough for the passengers to pass out, maybe the terrorists would have too, given that they commanded that the oxygen be "cutoff." Oh, and there's something about a spring loaded toggle switch associated with the pressurization system where one can manually drive open the outflow valves but that's mainly used for ventilation in the event of smoke in the cabin. But then they would have to turn both packs off in order for the cabin altitude to climb. Need I mention the positive and negative pressure relief valves on that system? I could go on and on. One last thought...there is no switch that I've ever seen on a civilian airliner which rapidly depressurizes the aircraft. Some military aircraft have them but they are a red guarded switch with black and yellow hash markings. They are used to depressurize the cabin so the airlpane doesn't pop like a balloon if hit by a missile or other things like bullets that enemy aircraft sometimes use. That's the theory anyway.

3. My memory is fuzzy on this one so I'll keep it short. And also why it's number three on my list. Supposedly, the passengers were alleged to have used a drink cart to break down the cockpit door while the terrorists were supposedly saying "hold them out" (from the inside). I believe the flight deck door on that aircraft opens out towards the cabin so, well, you can probably guess where I'm going...but agin, I know that those doors conventionally open out but that one could be different. Just throwing it out there. If someone can clarify that for me that would be great.

4. This one is trivial probably, but apparently, one passenger said something like "we better go now because if we don't we'll die." I guess that passenger or someone else on the flight had the skills, knowlege and ability to fly the 757 to a safe landing. Then again, maybe not. No deadheading pilots ever mentioned in any manifest I ever saw.

5. the information previously in this spot has been deleted due to an innacuracy of information as pointed out by a fellow aviation expert. I welcome further comments challenging the accuracy of the information in this post and apologize and stand corrected on the incorrect flight levels. Just interested in the truth.