Originally Posted by
Machinbird
JD-EE, we were temporarily lead astray by forum members who apparently believed that autotrim would not resume control once you made a manual trim input.
That would be me, having misread the documentation I had.
I strongly suspect there is some misinformation adrift in the Airbus community that needs correction. I wonder how BEA will address that?
Again, it was just me - the "Airbus community" were the ones who kindly corrected me via PM.
Originally Posted by
Machinbird
The problem with the trim is that it moved to a high aircraft nose up setting without crew awareness.
But all indications suggest that the PF was commanding the elevator and by extension the THS to do just that - it didn't do it on it's own.
It appears that a FBW aircraft requires the pilot to know exactly what mode the aircraft is operating in or else the question arises, "What's it doing now?"
Not true. "What's it doing now" usually applies to modern autopilots (i.e. FMS/FMC), which are not restricted to FBW aircraft (the 757, 767, Classic and NG 737 and 744 have them for starters), nor indeed Airbus. As far as trim goes, all you need to have in the back of your mind regarding modes/laws is that in anything other than Direct Law and below, autotrim is active, so one needs to be wary of large, sustained inputs.
Originally Posted by
CONF iture
You are WAY out DW, and should know better ...
Really? How else am I to interpret at least 5 years of posts demanding that Airbus return to interconnected yokes and introduce a big red "Direct Law" button (as in the 777), not to mention continued belief in a conspiracy surrounding AF296 @ Habsheim?
Originally Posted by
rudderrudderrat
If you keep taking tactile feed back away from a pilot, then you reduce him/her to a visual clues only input processor. If the FBW computers couldn't cope without valid airspeed information, is it a bit too much to expect a human to do a better job without the benefit of a "conventional aircraft's elevator feel"?
But "tactile feedback" has been artificially driven in every major airliner designed since the late '60s, and indeed is computer-driven in the case of the 777 - so if you're in a situation where you don't trust the aircraft, who's to say that the feedback you're getting is accurate?
Also, the FBW computers coped just fine with the loss of airspeed information. The A/P and A/THR kicked out, and some protections were lost but ultimately the pilots had a controllable aircraft.
Originally Posted by
JD-EE
And I believe we are in agreement with gums about the word "protections." The word sets up the wrong mindset leading to people getting reckless and cavalier about deadly serious subjects.
The problem is that "limits" (gums' suggested term) does not adequately describe what the system will do for you - for example, the Alpha Max/AoA protection will spool the engines to full thrust in the case of a sudden nose-up input - that's not a limit, it is - for want of a better term - a "protection". Also, your comment suggests that you believe some consider the existence of protections and their description as such might lead to a false sense of security - but from what I've learned from this thread, conscientious FBW Airbus pilots seem well aware of the limitations of said protections and the modes/situations in which they will not function.