Originally Posted by
_Phoenix_
Dozy, please revise the FDR graphics of XL888 and AF447. How is it possible that THS is maintained at max nose up position while AoA > AoAmax = stall warning on, for a prolong period of time?
Why the code doesn't implement a line:
If THS<-10 AND AoA>AoAmax Then MOVE(THS=0, rate X(AoA))
Two reasons.
- The code is not keyed in in that manner, as I said in the linked post - the logic paths are mapped graphically in the development software, and the actual code is generated by machine from pre-tested blocks of logic. These blocks are then further tested as a module, again in conjunction with the other modules and finally regression tested as a whole - a process that at the time could take several weeks per module, and could well end up being revised based on what the test pilots brought back from flight testing. The A320's systems took 6 years (plus a further 2 years beforehand on the A300 testbed) to develop for a reason!
- (Perhaps more importantly) In Alternate Law (AF447), the computers defer to the input of the pilot - in this case the THS moved and stayed put because the PF was pretty much consistently pulling up. If he'd let go, then the "soft" protections would have started returning the THS towards the centre, and if the pilot had pushed forward for long enough, the THS would have moved forward significantly faster. In Direct/Abnormal Attitude Law (XL888), autotrim is off and all THS movement must be ordered by the pilot via the trim wheels.
Originally Posted by
roulishollandais
DozyWanabee, do you know who was sitting in the right seat and in the jump seat from the two copilots ?
Well, we're talking about the A300 test bed from what I can make out, not the A320.
But regardless, I'm sure BZ would have been present for the "photo-op" flights, as befitted his title. But the actual grunt work of doing the thousands of hours of flight testing, as well as refereeing the discussions between the engineering pilots and the aero/software engineers would have been done with GC in charge. Baud was chief test pilot, so of course he'd be in the LHS a lot of the time - and for the earlier test flights it would make sense to have GC in the RHS as monitoring pilot, as it was his job to evaluate the systems and how well they were working, so he could take reports back to the engineering teams and fine-tune them.
About your last questions it seems that our interpretations are different. No problem.
With respect, it's a little more complicated than that. It seems to me that you've come up with a conclusion based on your own beliefs (namely that FBW technology has eroded piloting skill), and are reading the graphs in such a way that fits that belief. What should be happening is that the data should be used to draw conclusions, not the other way round. The interpretation I presented (with regard to ageing airframes and older jets being sold to less safety-conscious markets) is not actually my interpretation, but those of many articles, papers and books I've read on the subject over the years - most of which I hope were written by people who had access to the supporting data needed to draw those conclusions.