Originally Posted by
A-FLOOR
What was also significant in the AF447 case is that (...) the FBW will mask any change in roll response of the flight controls due to the extreme AOA, as I recall that the roll rate response vs. stick deflection is linear in alternate law. FBW being FBW, it will always try to give you what you are asking of it.
No. In Alternate 2 law, roll is direct. Meaning sidestick deflection gives proportionnal control surfaces deflection. This is different than the normal mode, and FBW doesn't try anything here, no "masking".
Originally Posted by
A-FLOOR
With regards to Airbus vs. Boeing: the Airbus overspeed mode was commanding an increase in pitch through the flight directors, which was followed religiously at least until the aircraft reached its apogee at 38000ft.
What flight are you talking about
If still AF447 : sorry, this one never get to overspeed.
Originally Posted by
A-FLOOR
(...) even though the captain correctly remarked on his return to the FD that the aircraft was stalled.
Same question. If that's AF447, I fail to see anything suggesting any of the crew members ever understood the stall situation.
Originally Posted by
A-FLOOR
This tells you how a Boeing would have fared in the same situation: the lack of autotrim on Boeings leaves the THS in the same position unless you conciously tell it to do something else using the trim switches, and this leaves open your avenue of sensing that the aircraft is stalled as you are unable to maintain a nose-up attitude as the aircraft loses airspeed.
Two remarks:
- It still remain to be proved that elevators only aren't enough to maintain stall (at a lower AoA than that obtained with the help of the THS, maybe). IIRC knowledgeable peope (of which I'm not) suggested otherwise.
- What do you mean by "the lack of autotrim on Boeings"?
[edit] May I suggest we move to the AF447 thread if I undestood correctly that was the topic at hand? We're hijacking flyburg's thread, here.