Originally Posted by rudderrudderrat
The controls would feel lighter than normal - just like roll in ALT LAW
Thereby making it easier for the pilot bent on pulling to overstress or stall the aeroplane? Isn't it unsafe design? Unlike airbus where you are presented with constant stick force?
Of course I'm indulging in mockery here; both constant force sidestick and syntethic feel yokes are well thought-out systems with good and bad sides. Pilots who use them must be well acquainted with their normal and abnormal behaviour. PPRuNers would do well to remember that "natural feeling" yokes are in reality dependent on whole lot of instrumentation and electronics to simulate DC-3 like feel in modern aeroplanes.
Originally Posted by Lyman
Buffet was not noted on CVR
Neither was any explicit comment on stall warning, however there was an inanimate object that provided some clue on CVR:
Originally Posted by BEA final report on AF447, English edition, page 93
This modification of the behaviour resulted in the appearance of a high frequency
component of an amplitude increasing to up to about 0.1 g peak-to-peak, and with
a signature that is very different from a turbulence signature of aerological origin.
Furthermore, there is a noise on track 1 of the CVR, at about 2 h 10 min 55, which may
be the impact of the microphone striking a panel, heard at a stable frequency.
Originally Posted by Lyman
Buffet was determined by analyzing accel.
Well, not just that. As pre-stall buffet is defined and measured at cockpit and IRS tend to be near C.G...
Originally Posted by BEA final report on AF447, English edition, page 93
Additional analyses were conducted with Airbus to determine if this phenomenon
could correspond to buffet. The identification of this phenomenon is complicated by
the fact that the concept of buffet is defined as accelerations at the level of the pilots’
seats and not at the centre of gravity.
..some test flights were flown:
Originally Posted by BEA final report on AF447, English edition, page 93
Airbus subsequently flew special flights to collect more accurate data at high angles
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10
min 57 s during the accident flight
However, I believe 1g to be a typo in both French and English versions. 0.1 G is more likely and nevertheless represents very significant vibration. At 1G amplitude, aeroplane would be buckling like mad.
Originally Posted by Lyman
The aC did not pitch nose down at Stall.
Because CM2 got in his head that he has to keep the nose high, even if it meant setting TOGA and pulling all the way back. That's the only constant about his behaviour; he pulled when stall warning blared, he pulled when it did not. He pulled when F/Ds told him to pull, he pulled when they were knocked out.
He was quite successful in keeping the nose high, too.
Originally Posted by gums
pull and pull to the limits and run outta energy while transitting the stall protection limits, then get to new territory. pushing forward would have equally bad outcomes if the "overspeed" "protections" ( how I hate that term) are FUBAR due to invalid speed inputs to HAL.
We are getting somewhere. Insane pushing could eventually get as dangerous as insane pulling. So question is why push or pull at all? Many a crew has survived the UAS ordeal by making no reaction to turbulence induced, high Ma induced low threshold stall warning at all, just keeping the usual cruise attitude. They would if they have gone for memory items, too.
Originally Posted by gums
From the CVR fidelity ( could detect switch changes) and the comments by the troops, doesn't sound as if the AB330 has pronounced buffet in the stall regime.
I don't mind having shaker or blinking red STALL light installed on Airbi. I explained why it was not required to be installed. Also I believe it would not make a lot of difference in AF447: I'm not buying aural saturation theory. Seemingly CM2 disbelieved everything he has seen or heard and somehow got idea pulling will get him out of the situation. Too bad he didn't comment out loud what he believed was going on, like capt of Birgenair 301 that first told his crew to disregard the warnings only to break down a few minutes later and dismiss every speed information as false, when 2 out of 3 were correct.
Originally Posted by slats11
Why did the Captain not get a useful handover when he returned to the cockpit?
Because co-pilots' performance in the cockpit was not matched to circumstances and can be described as useless.
Originally Posted by slats11
Had things already degenerated that much.
In my book, 40° AoA in public transport category aeroplane is that much degeneration.
Originally Posted by Turbine D
Guess the TAM folks proved the Air France FCOM wrong?
Pardon my level2 English: I meant to say that usual Frankensteinan idea that aeroplane has suddenly turned into monster prepared to kill her masters at the slightest provocation, which surfaces almost every time someone is killed in aeroplane accident, has no merit. FCOM recommendation to manoeuvre with care absolutely doesn't imply that very gentle adjustments of the sidestick are required. While TAM crew went against the recommendation of care, their roller-coaster ride did prove you can get away with being severely ham-fisted in high-altitude manual flight, as long as amplitude and average of your shenanigans keep you inside the envelope.
In law degradation, or control problem or whatever, control displacement or force gets second seat to taking feedback from instruments! "Hoot" Gibson did not care a little bit that post-dive it took him almost full roll control and considerable force to keep the aeroplane level, he was just interested in keeping it level and applied as much deflection and force as needed to achieve that goal. As should any instrument rated pilot.
Originally Posted by Turbine D
I am sorry Sir, that I gave you credit for something that didn't deserve credit.
Apology accepted.
Originally Posted by rudderrudderrat
It's a clue that you've just entered a region of much warmer air suddenly.
No trace of it on FDR concurrent with the comments. Blockade of TAT probe did rise the apparent temperature 40 seconds after the comments were made.