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Old 5th Aug 2011, 12:42
  #1588 (permalink)  
Join Date: Jun 2009
Location: Paris
Posts: 691
Hi Old Engineer,
Originally Posted by Old Engineer
I'm noting that this -5000 fpm appears to be without flight deck input, so I'd say the graph is saying something critical to us.
Before AP disconnecting (at 0210:05) the graph is showing a VSS of zero, not -5,000 ft. (one need to read the discontinuous green line) and the red line (real V/S) is not altered in any way by it. It is also showing a different active mode when autoflight is still ON.

The cyclical drops (regular pikes down to MIN value) is certainly due to this autoflight mode (hence normal). In fact, I did not comment on those regular pikes as nobody here knows how those values are sampled. The same channel may be used, when AP is ON, for recording another flight parameter at regular intervals. It looks for me to behave this way.

After FMGECs faults (at 0210:05), the mode change is obvious, next VSS value increase/decrease is now linked with FD resetings. But, before this point, the VSS values (including MIN) are not linked with FD as there is another graph for FDs showing nothing anormal before UAS.
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