PPRuNe Forums - View Single Post - AF 447 Search to resume (part2)
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Old 9th May 2011, 17:34
  #1011 (permalink)  
RetiredF4
 
Join Date: Jun 2009
Location: Germany
Age: 71
Posts: 776
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zoom-boom scenario

I´m somewhat astonished concerning this scenario.
Flying at FL 350 with a still heavy aircraft, how much climb could be produced even with full power? Is there enough elevator authority available to get the climb rate going to reach such an AOA and how fast would airspeed degrade? Gums with his F16 could have done it, my F4 would just have produced a lot of drag on such an elevator input and would have picked up a descent rate instead of a climb rate.

Next question is, at what point of the events and with what kind of airspeed could this pitchup have started? Icing of pitots, therefore unreliable airspeed (not known to the crew jet), turbulence and autothrust of, stall onset at the low speed region (not clearly identified by the crew yet, might be mixed up with turbulence issues). Crew-action increase thrust leading to pitchup (underslung engines, unfavorable CG), with slowing down descent rate, but not curing the pitch problem (correct speed still not known to the crew, work overload, turbulence.....). Nose stays up crew reduces thrust again..........

At what forward speed would we define the upset (if it happened) from FL 350 to FL100 and then on down to the water? If the normal flying speed is 470 KTAS in FL 350, is the thing still flying with 300 KTAS? Per my definition the aircraft would be out of flying speed way before the previous mentioned 60 KIAS from other posters.

The going down in a upset condition would probably never be in a straight line, struggling with a falling aircraft in free airspace directional control would be my last worries. It might have done one or more turning/ yawing motions around the vertical axis, it is at least more probable in an upset than a straight line. That sums up for the missing time. And it might not have been a continuous upset, secondary stalls are quite a common encounter in well controlled training environment (planned, briefed, prepared and good weather).

I´m not saying, that´s what it was.

franzl
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