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-   -   FBW question (https://www.pprune.org/tech-log/554797-fbw-question.html)

Microburst2002 27th Jan 2015 17:46

Airbus sidesticks could be enhanced with a stick shaker, I suppose, but nothing more. Stick force must be totally independent of speed.

However I think that a loud "STALL STALL STALL…" aural warning is enough, at least for me.

In the case of the AF I don't think that a Boeing style fbw would have made any difference. They would have just done the same, pull the yoke till death. The airplane was airworthy, although somewhat challenging to fly.

It is human factors that have to be addressed. They were taken by surprise and they never recovered for it. They were so "in the red" and the tunnel vision so so narrow that they became effectively incapacitaded. Both of them. I wonder what rol had fatigue, complacency, health, etc in that incapacitation.

CONF iture 28th Jan 2015 01:43


Originally Posted by M2002
In the case of the AF I don't think that a Boeing style fbw would have made any difference. They would have just done the same, pull the yoke till death.

Little chance that the right seater could have maintained the yoke on his stomach for a 30 sec period just as the captain came back ... What a HUGE input for both the captain and the left seater on what's going on ...

Microburst2002 28th Jan 2015 03:44

Maybe, but I think they were incapacitated, otherwise, the other pilot would have prompted the PF to pitch down. You don't just sit there silent while such a mess is going on. They lost their ability to manage the situation.

In the Boeing they would probably have pulled both together from the yoke when the other pilot noticed that the PF had difficulties in pulling.

CONF iture 28th Jan 2015 17:53


Originally Posted by M2002
In the Boeing they would probably have pulled both together from the yoke when the other pilot noticed that the PF had difficulties in pulling.

I doubt that as the first action the left seater did when he grabbed the stick was to push on it.
Never he or the captain realized the right seater was maintaining full back stick for a 30 sec period.
They had lost confidence in the FCS to the point to shut down some computers.

When the left hand has no idea what the right one is doing ...

DozyWannabe 28th Jan 2015 20:16

What computers did they "turn off"? to the best of my knowledge, there's no evidence of that...

CONF iture 28th Jan 2015 21:35

PRIM1 SEC1
 
http://www.pprune.org/7382441-post158.html
http://www.pprune.org/7383280-post164.html

DozyWannabe 28th Jan 2015 21:57

Hold up - that's not proof, those are two of your own posts in which you seem to have derived your own theory based on your interpretation of flight surface deflection.

To the best of my knowledge there's nothing in the DFDR/CVR evidence which explicitly suggests any of the FCCs were turned off. Without either of those as supporting evidence, it must be considered as a strong possibility that your suggested disabling of FCCs did not in fact happen.

[EDIT : Some discussion went on on the next page of the thread - AZR wondered if the PRIM1/SEC1 FAULT messages tallied with the CVR (albeit very late in the sequence and not as a consequence of following any kind of procedure). I guess the question for me is whether manually turning them off would result in a FAULT ECAM message or whether it would say something different.]

[EDIT 2 : In fact, I'll quote AlphaZuluRomeo's response:


2 h 13 min 28,2
PNF : essaye de trouver ce que tu peux faire avec tes commandes là-haut (my note: the PRIM/SEC commands are on the overhead panel)
2 h 13 min 30,4
PNF : les primaires et cetera (my note: "primaires etc." may refer to the PRIMary and other computers)
CPT : (* fera rien)
2 h 13 min 31,5
CPT : on (fera /verra) rien

And then:
2 h 13 min 45 F/CTL PRIM 1 FAULT
2 h 13 min 51 F/CTL SEC 1 FAULT
...
The transcript show the PNF to want to "try" something with the "primary" (computers?) then the captain answering it will be no use, then the PRIM1 & SEC1 to be switched OFF.
Even that interpretation is vague enough to raise questions. If the PNF wanted to "try" something, was it simply turning PRIM1 and SEC1 off, or did he mean to attempt a reset (i.e. switch them off and back on)? In any case, all of this happened well after 02:12:30, which is the probable last timestamp in which recovery might have been possible given the aircraft's scenario.

Linktrained 28th Jan 2015 23:57

"10,000 ft."
Was this said as a matter of routine... Or with surprise, when cruising over the Atlantic ? It appears to be the first recognition of the direction of travel recorded on the DVD.


No comment that the THS was only moving in one direction, NU, steadily. Would this be likely, when the aircraft would normally be in nearlv level flight.


I was a newby Second Officer, doing "my hour" of hand flying at night, as the A/P was u/s. I flew into an unseen Cb. The Captain told me to "Fly reasonably straight and reasonably level." Which I did. ( We had heard of someone who had tried something else with bad effect.)


Rain soaked through the unpressurised windscreen and wet my knees.


(Radar did not come, for me, for a dozen more years.)

NeoFit 29th Jan 2015 00:15

DZ wrote

What computers did they "turn off"? to the best of my knowledge, there's no evidence of that...
Not really, in fact but ....


27 F/CTL PRIM 1 FAULT 2:13
27 F/CTL SEC 1 FAULT 2:13

----> Flight controls computers set OFF or reset
2012_ISASI_Airbus_presentations.pdf ( link )

c100driver 29th Jan 2015 02:27

May I respectfully ask if you want to specifically argue the AF447 issues you move it to the AF447 thread please.

vilas 29th Jan 2015 04:17

AF447 is like a hydra headed monster. You chop one another one pops up. It appears to me that dragging any airbus topic to AF447 is a favorite past time of some participants.


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