Originally Posted by John Tulamarine
Done .. JT
Thanks!
Originally Posted by OK465
IIRC OG suggested that the system will then 'see' the g is not as commanded and then continue to increase elevator deflection to eventually match the commanded or available g for a much lower speed than 330 KIAS. (My observations showed some number of seconds involved)
While precise and correct answer could be provided only by Airbus FBW experts - and I strongly suspect any of them reading AF447 threads must be howling with laughter - I find such interpretation quite implausible because:
1. certifying the FCS that significantly increases your pitch rate over couple of seconds while holding the constant stick deflection would be waaay too much even for the most corruptostupid aerogovernmental people inhabiting the imagination of PPRuNe's resident Airbus bashers.
2. From my 320 initial training I remember that FBW was trying to mask the fact it was losing control authority as much as it was practicable. Stabilizer lost or one elevator on vacation with other limited to 50% throw not to overtorque the empennage? No problem or perceptible difference as long as the speed was up. Maneuvering for approach with two hyds shot up felt normal enough but when abrupt maneuver at low Q needed to be performed, i.e. last moment go-around, it tended to turn quickly into wrestling match with the aeroplane.
3. Final report says:
Originally Posted by Page 186
In alternate 2 law, the longitudinal control law remains a load factor law and the
lateral control law is a direct law. In the specific case of alternate 2B law, some
coefficients used in the longitudinal flight control law become speed-independent
and are set for the maximum speed for the aeroplane configuration (330 kt in clean
configuration). This hardly modifies the behaviour of the aeroplane in comparison
to normal law, but can nevertheless induce an unusual response dynamic when the
aeroplane has an abnormally low speed for the configuration.
Originally Posted by Waldo Cerdan
Was the risk adequately appreciated?
Yes. Thirty cases with not as much as scratch to anyone or anything were appreciated enough... till the 20-20 hindsighters took over.
Originally Posted by Lonewolf50
Based on the limited evidence available to us, which is some of the CVR transcript, I'll suggest that neither Bonin nor Robert ever got to the "frightened" stage. They remained in the "what is going on?" stage, though Robert seems to have been more aware of the aircraft's flight condition than Bonin, coupled with frustration and confusion.
Oh, they quickly went from frightened to completely shocked. They were climbing with 7000 fpm, above their performance ceiling and could not connect the fact with blaring stall warning. It's textbook panic - very unlike the Hollywood one.
Originally Posted by PJ2
"...over the ocean" makes no difference, neither should night-time if one is an instrument pilot
WoCL is a four lettered word.
Originally Posted by Owain Glyndwir
The question is WTH was this not carried over to Alternate laws???
Because ALTN laws are made (inter alia) for cases of air data getting screwed up! It would be no good if false data unnecessarily rob the pilot of control authority. No matter what John Cashman, Bernard Ziegler or CONF iture might say, in FBW Airbi pilot still has the ultimate responsibility to recognize the problem and more than enough control to solve it properly.
Originally Posted by RetiredF4
The manuals are comparable to instruction manuals without comunicating the basic knowledge layer behind those instructions.
How many times have I posted the disclaimer from the very beginning of Airbus manual in previous AF447 threads? IIRC at least three.
Originally Posted by gums
The insidious effect of the implementation and the lack of speed/AoA stability until in direct law was a very big player.
Not in AF447 case as it didn't pitch up with neutral stick.
Originally Posted by BOAC
So, we are back to having something saying "That's enough mose-up THS, boys and girls - if you really want more push this over-ride button" - what is wrong with the concept?
Maybe not completely wrong but surely it's spectacularly incongruent to bash Airbus FBW for taking away the full control authority from pilot and then cry: "Help automatic trim cut-out, save us from ourselves!"
Originally Posted by roulishollandais
Boeing's Synthetic airspeed, Airbus BUSS, safe USN's AoA, or Klopfstein's old inertial HUD.
...can not alter the fact the unreliable airspeed procedures work when applied even with no alpha gauge, HUD, BUSS or whatever.
Originally Posted by RetiredF4
Correct would be the airplane will maintain a loadfactor of 1g.
It would be correct except for the fact it isn't.
Originally Posted by RetiredF4
That mindset "set the pitch and it will stay there (and go there) might have influenced Bonins actions with the SS.
So, he was desperately trying to achieve 20 degrees pitch on cruise level?
Originally Posted by tartare
Big, vulnerable ocean liners of the sky that are pretty much optimised to point directly into a high mach airflow, and stay there.
'Tis a miracle thousands of them keep themselves pointed into high mach airflow day after day, year after year and survive despite their vulnerability.
Originally Posted by gums
I do not feel we should go to a "direct" law post haste, as even that requires electrons from the flight controls to the control surface actuators. But the plethora of modes and sub-modes on the 'bus puzzle me.
You are puzzled because you have never tried them, in the sim at least, but rather built up your misunderstanding of Airbus FBW on usual PPRuNe mix of prejudice, ignorance and outright libel.
Originally Posted by Flightglobal
Safran’s exhibit featured a two-seat cockpit simulator with sidesticks on either side. Unlike passive sidesticks found commonly on Airbus commercial airliners, the active system integrates a digital feedback loop. It allows pilots to feel how the aircraft responds to control inputs. As control forces climb higher, for example, the stick feels heavier. Over-speeding the aircraft triggers a vibration in the control stick to warn the pilot.
Stickshaker as overspeed warning.... now that makes almost as much sense as 12 threads on AF447 here.
Now back to our usual reaction eliciters.