PPRuNe Forums - View Single Post - AF 447 Thread No. 8
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Old 26th Apr 2012, 15:39
  #206 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,610
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So back to Alt laws and such

Looked up the "laws" and reversion sequence again, and seems the system continues to use "normal gee" as the pitch command, and roll rate, but not roll angle "protection". That right?

So why have to hold back stick? Further, the 'bus has a pitch attitude correction for the Nz the plane tries to maintain with stick neutral. Otherwise, at just a few hundredths of a gee less than 1 gee the thing would continue to go nose up in order to maintain 1 gee. We saw this in our little jet once pitch was above 10 or so degrees, and it was quite noticeable above 30 deg of pitch. What, 0.87 gee for constant pitch angle?

I understand some folks pointing out a rapid roll change just after UAS could be disturbing, but seems about right for a bit of turbulence.

I can also understand a very slight nose up command if worried about overspeed, but only for a few seconds and then back to whatever pitch was before the UAS.

The CVR comment about crazy speed might be explained, as vertical velocity was extreme but indicated speed was what, 107 or 135 knots? So PF wondering about why such a slow speed if descending so fast. Maybe started to question the altitude readings, too, for first 30 or 40 seconds.

As another contributor has opined, this will be a "landmark" report and I think the recommendations as well.
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