PPRuNe Forums - View Single Post - AF 447 Thread No. 9
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Old 13th Aug 2012, 21:00
  #1267 (permalink)  
gums
 
Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,610
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THS time response

In a limited defense of DOZE, I submit:

With a traditional empennage design, and with all control systems functioning, it is never completely impossible to un-stall the aircraft due to aerodynamics unless cee gee is so far back that the jet has lost it's normal longitudinal static stability or the horizontal tail/elevator has lost a positive/negative pitch co-efficient. The limiting factor is purely time (i.e. how long you have before running out of altitude to recover), and if the PF had pushed the stick forward and held it there, the THS would have come forward and recovery would have been straightforward in a matter of a few seconds (presuming that the recovery was effected with enough altitude to spare).
Other than the aft cee gee problem that we had with the Viper, I agree. Holding stick forward for a few seconds should see the "auto trim" kick in to allow reducing stick fwd/back pressure, just as if you rolled the trim wheel. Secondly, you don't want a short time constant on the auto trim. A few seconds, like 3 or 4, should be about right. Otherwise, you could have a "computer-assisted PIO", as if the auto-trim reacted in a tenth of a second, heh heh. Can also average the stick inputs for a few seconds and not require a constant 1.3 gee or -0.85 gee command. Ahhhh, the wonders of a FBW system.

I agree with several here that the auto-trim did not help, but I agree with those that maintain it was not the major contributing factor. No doubt trimming nose down using the wheel would have helped, but that didn't seem high on the priority of the PF. And the nearly constant nose up command seems to me to be the most damning crew action.

I am becoming upset with the "personal" stuff I have seen lately.

If anyone wants to attack me, then I already have my kevlar flak vest on and NOMEX shirt.

Otherwise, I would prefer to see a more "professional" dialogue, as the name of this forum implies.

Last edited by gums; 13th Aug 2012 at 21:06.
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