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.

Neither was any explicit comment on stall warning, however there was an inanimate object that provided some clue on CVR:

Well, not just that. As pre-stall buffet is defined and measured at cockpit and IRS tend to be near C.G...

..some test flights were flown:
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.

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.

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.

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.

Because co-pilots' performance in the cockpit was not matched to circumstances and can be described as useless.
In my book, 40° AoA in public transport category aeroplane is that much degeneration.

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.

Apology accepted.

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.

Just to make sure that it is now understood, that after the initial pull with too high pitch attitude "not pulling" anymore" would not have been the solution to get the nose down by itself. A nose down push is necessary to change the trajectory in ALt2.

See below. I know, that Oozlum bird again....


BEA final report 2.2.5 (my bolding)
However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at constant thrust. Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick.

OK so no spike in TAT concurrent with increased cockpit temperature.

So what else can suddenly lead to increased cockpit temp? I mean both guys commented on an abrupt and significant increase in temp. That's odd surely. So what are the possible explanations for this? (other than increased TAT overwhelming climate control which the evidence does not support as the explanation)

BEA#3 page 17: BEA#3 page 44: I don't think it is a typo. Buffet onset is defined as 0.2 g and is considered the lowest level of perceptible buffet. The buffet onset boundary is scheduled in the FCOM and QRH. In the conditions of AF447 it occurred at M=0.64 and AoA=7.7 degrees. The 'deterrent' buffet described on page 93 of the Final Report is so severe that it is considered an effective deterrent to further speed reduction, so that in certification stall tests the airplane would be considered 'stalled' and recovery would be initiated as soon as that condition is reached.

P.S. Sequence of AF447 events:
02:10:51 AoA=6 deg, stall warning triggered
02:10:53 AoA=7.5 deg, buffet onset
02:10:57 AoA=10 deg, deterrent level of buffet reached

Hi slats11,
There are very few TAT recordings reported.
However, please see the report published in July11, page 86.
Time 0hr.09min FL. 34.992 Static temperature (°C) -43.5
Time 2hr.10 FL 35.044 SAT -38.8

From the CVR report:
02.06.54 the crew say "Minus forty-two we won’t use the anti ice that’s a plus."
02.08.41 "What's that smell" .. It's Ozone...You can feel already that it's a lot hotter...It's amazing how hot it is all of a sudden.."
02.09.40 Change in background noise (from impact ice crystals)
02.10.03 Engine anti ice is turned on (in response to TAT being warmer than -40)

The TAT has warmed from -42°C to -38.8°C over a very short time.
They must have just entered the warm rising air of a CB.

The Turbine Bypass Valves in the Air Conditioning Packs move slowly, the SAT rise was felt by the air conditioning temperature rise.

OK. But this is at odds with Cllandestino

So did the outside temp really increase as the crew believed (and turned on anti-ice)? Or was this increase due to a blocked TAT probe?

OK. Assuming they are talking about increasing cockpit temp rather than outside, I guess the possibilities include:
1. Increased heat production within cockpit. Unlikely.
2. Increased transfer of heat into cockpit. Increased outside temp and lag in climate control adjusting for this would be one cause, but there are others..
3. Decreased transfer of heat out of cockpit.
4. Loss of (or decreased ) air flow around the pilots leading to decreased evaporative cooling. This would only cause an perception of increased temperature rather than a true increase in temperature.

Many of these explanations involve altered internal air flow. So what exactly is the "change in background noise" noted twice at 02.08.17 and 02:09:40. During this 83 second period, the PF questioned whether the PNF had adjusted the A/C, both pilots noted a smell of ozone, and both pilots noted increased cockpit temp.

I can accept increased TAT due to rising air from Cb, and this explains the ozone. However Clandestino states TAT did not rise during this period, and further that the FDR did not record a change in vertical acceleration.

If Clandestino is correct, there must be another explanation for the increased temperature. The changed background noise and the smell of ozone (or whatever) may be relevant to this explanation.

Lyman,
Yes, my question was rhetorical. I fail to see what the temperature has to do with how the crew handled the last four minutes or so of "flight".
Slats wrote: The captain seemed very slow to act.
Slow to act? The captain did not act at all. He merely dispensed advice, some of it useful (use the rudder rather than the ailerons), some of it not (repeatedly urging that the wings be kept level), and at one point exclaimed despairingly "Damn, that's not possible!" (without specifying what wasn't possible).
I always thought the captain is the guy who's supposed to take over when things go pear-shaped.
Slats is also under the impression that the PNF had better situational awareness than the PF.
This is debatable. When the PNF formally took control from the PF, at 2:11:37.5, instead of pushing the sidestick forward, he held it hard left exactly as the PF had been doing. That's just one example of deficient SA. However, to his credit, the PNF did realize that they were not in an overspeed condition and told the PF smartly to stow the speed brakes that he was deploying at max thrust at FL297. Incidentally, this episode elicited no comment from the captain.
No, Lyman, you could not make this stuff up.

Blockage of TAT probes tend to occur suddenly, similar to pitots. In this case the TAT rose gradually between 2:09:52 and 2:10:04, while the airplane was entering a vertical gust that reached 22 kt at 2:10:03.5 - see figure 64 of the Final Report, the correct one, not the figure 64 erroneously included in the English version.

Hi slats11,
It probably is - but I'm using BEA's reports as my reference, not something that Clandestino thinks.
From the CVR report 2012, page 23:
"2 h 09 min 46. Background noise increases (typical noise of impact of ice crystals, identified by A330-340 pilots) "

The autopilot was engaged, flying ALT CRUISE. Why do you think there would be a change in vertical acceleration? The AP would simply reduce the pitch attitude slightly.
I posted the FDR TAT record in my previous, and the crew's observation of the TAT.

They are all classic symtoms of flying into CBs.
Excuse me if I don't hold my breath.

Fair enough. Thanks for clarifying. So then why did both pilots notice increased temp more than a minute before the TAT increased? If rising TAT led to increased cockpit temp, then the sensed TAT (measured externally) should rise before this warmer air led to increased cockpit temp.

Sure, the report explains this instance of increased background noise as being due to ice crystals. It makes no interpretation of the two previous references to change in background noise at 2.08.17 and again at 2.09.40. The CVR transcript merely states "change in background noise". These comments are earlier, on page 22.

Y'all have been having some fun since I last visited.
I'd rather be in a bar with you two, talking this over, a few pints included. T'would be goodness.
Your analysis, not necessarily a fact. But I'll bet with your read on that one, if we have to go to Vegas on that.
gums
This is CRM training module X: What does it take for the copilot to say "I have the controls," take the controls, and make the right thing happen? Over to the cockpit gradient sub discussion we go ...
The PF was task saturated. As I analyze the event, PNF had at least partially bailed out (mentally) when he called for adult supervision. (Aircraft Commander). The clue to this for me was the "where is he" and frequent call up.
That aside, the time and environment for "briefing" is when you are in control of the situation. The two up front were, from the evidence, NOT in control of the situation, but were playing catch up.
slats:
Yep. Fatally perplexing.
That's how I'd bet it in Vegas.
mm43
They were left guessing, but one wonder just what the "command climate" is at AF, and in AF cockpits. (Air France, not Air Force, about whom I have other doubts. :E)
Clandestino:
Training issue, and possibly an Airbus and Air France Indoctrination Issue. Education and training go hand in hand with indoctrination.

HN39 in re buffet: thanks, well explained!

I almost hear Linda Ronstadt singing "Heat Wave" in the background.
Well said. Truth is once again stranger than fiction.

maybe i can get some support from hf experts, because it`s quite difficult to explain with my bad command of english.
there`s something missing from the BEA report,which in my mind is one important cause for the crash.
the command structure in the cp when the cp left.Bonin was the assigned pilot flying although he was younger and had less hours on type.
Maybe there was one though on his mind,that when the cp returns,he didn`t expect that he,Bonin , had given up command.that maybe the reason for taking back command from dubois .And dubois thougth the same: the cp does not expect me having taken command when he comes back.
that could be the reason for such bad crm.
I´m sure had command been given to dubois by the cp that he would have taken command immediatley from Bonin because he had a right guess.

relaxed static stability
 

Thanks for finding that pearl about the static stability, Retired. Thank you, thank you.

For those that have not flown a FBW system that has "limits" or "protections" embedded in the flight control laws, you are only commanding control surface deflections when rotating on the the runway to get airborne. So if the system is using gee as the primary "command" or even "limit", then the elevators could be moving all on their own despite your stick inputs to achieve that gee. This is a player when at a steep climb unless the system compensates for the pitch attitude ( as the 'bus does in Normal law). The system will move the elevators and THS to achieve 1 gee, but you really should be commanded less than 1 gee. For example, at 30 deg of pitch we should be holding 0.87 gee to maintain a 30 deg pitch while climbing ( honest, the VooDoo required that until about 25K when in an afterburner climb). If you command 1 gee, then you continue to increase pitch attitude.

And now, Airbus shows us that the jet DOES HAVE a point on the pitch coefficient curve that is "neutral". It's why I jumped in here initially to show that the Viper has such a point and we didn't find it until well into the program. But the combination of relaxed static stability and the control laws ( gee command and AoA function) allowed us to get to a deep stall and stay there with hands off the stick. We got there by doing exactly what AF447 did - climb at a sufficient angle and power setting to run outta energy/aerodynamic effectiveness of the elevator before the system could get the nose down. I posited this scenario the instant I saw the graphic of the wreckage. Looked like a classic deeply stalled jet pancaking into the water at a high, very high AoA.

The BEA comment about positive static stability and stall entry was a good one. Before FBW, it worked. You had to work hard/pull hard to get to the stall. Let go and most planes would pitch nose down to achieve the trimmed AoA. But the FBW systems will allow you to get to the stall if the laws are heavily biased for gee command, and do not blend in AoA, pitch rates and so on.

The second "aha" for me was the buffet values were established. Certainly high enough for most pilots to realize that something was wrong, as in an approach to a stall. Before this, I felt that the jet was so smooth that a stall entry buffet was too low to provide a tactile warning. Personally, a buffet of 0.1 gee Nz seems adequate to provide a warning without any fancy chimes/clangs/etc. And a buffet much higher than that once in the stall should have been a very big indication of what the jet was doing.

The good news is that we can train to handle the situation, even prevent the situation.

I would also like to see Airbus use the AoA in conjunction with the gee command to keep the jet from trying for gee "uber alles". This is in alternate laws, as the thing seems to do this in Normal.

The air temp and ozone stuff seems irrelevant other than distracting the crew. And an apology to OKie. I wanted to fly the F-4 when it first came out, and even a C-130 if I couldn't make the cut for fighters. Nevertheless, I never wanted the degree of responsibility required to get a few hundred folks to their vacation venue, so took a pass on an airline job once outta the fighter community. If I screwed up, then it was my skinny butt and not a slew of others. Just my personal philosophy, and no offense to all here that have accepted the responsibility and have survived along with their passengers.

Captain's late return
 

With severe buffet at 02:10:57, the Captain would have felt it too. He must also have noticed an unusual, continued climb >1/2 min before that.

So why didn't he return to the flight deck earlier than 2:11:40, and should he even need a briefing from PNF to connect those dots?

I think that´s not a too difficult question to do some guessing answer.
While expieriencing buffet while flying through bad weather seems a normal and often expierienced event, buffet due to approaching stall sure was the first time in their life in an aircraft.

And even in the simulator AFAIK stall approaches are not trained with nose high attitudes but beginning from decelerating in straight and level flight.

The mindset of the complete crew was not orientated to a loss of control situation in the classical sense, meaning stall, but in the sense that the aircraft does not react like expected. "What´s happening? We dont know......"

In a full motion simulator we can feel climbs and descents, acceleration and deceleration along the longitudonal axis by just tilting the box. So pilots are not used to base their judgement on the bio vestibular system when lying in the crew bunk or being on the way to the cockpit.

When pitch is established (lets sáy 10°) and the aircraft is decelerating, the body would feel a descending sensation even if still climbing.


Answer see above.

Philip,
I think you have confused the cast of characters. The captain's name was DuBois, the left-seat copilot was Robert and the right-seat copilot was Bonin.
When the captain left the flight deck to take his rest, Robert had just returned from his rest. The captain did not unambiguously assign crew responsibilities in his absence. For example, although Robert occupied the LHS, the captain did not explicitly designate him PIC.
What do you mean by "cp"?

@slats11.....

"OK. Assuming they are talking about increasing cockpit temp rather than outside, I guess the possibilities include:
1. Increased heat production within cockpit. Unlikely.
2. Increased transfer of heat into cockpit. Increased outside temp and lag in climate control adjusting for this would be one cause, but there are others..
3. Decreased transfer of heat out of cockpit.
4. Loss of (or decreased ) air flow around the pilots leading to decreased evaporative cooling. This would only cause an perception of increased temperature rather than a true increase in temperature."

Could I add...

5. Loss of dedicated cooling to the avionics.

A lot of stacks of heat producing equipment. If I was a smartie, I might exhaust the heated cooling air from the avionics bay into the cockpit environment?

Might that explain the smell?

Might be easy to check, it could be entirely off base... If a fan motor went tu, could it produce the noise referenced by BEA as "increased cockpit noise" (unidentified)?

BWV988

02:10:51 AoA=6 deg, stall warning triggered
02:10:53 AoA=7.5 deg, buffet onset
02:10:57 AoA=10 deg, deterrent level of buffet reached
With severe buffet at 02:10:57, the Captain would have felt it too. He must also have noticed an unusual, continued climb >1/2 min before that.

So why didn't he return to the flight deck earlier than 2:11:40, and should he even need a briefing from PNF to connect those dots?

Long ago, I reminded myself that a return up the aisle to his (Captain Dubois) office would be seriously "uphill"... Quite a climb actually...About four times as steep as he may have "expected". He walked into three seconds of STALL WARN, so combined with the uphill climb and the chirp of STALL: "hey knucklehead, get the nose down, you looking for a swim?"

At this point, and due to Autotrim, if he continued to use Approach to Stall recovery method, he would merely "relax" back pressure, not actively lower the nose, and the THS would prevent the nose from dropping, further confusing the frustrated recovery... If there was one.

As a non-aviator I was interested in the many posts referring to Buffet. So I did a little research on my own with the hope of understanding this phenomena. I think I have a basic idea of what Buffet is. (Both over speed and under.)

So, the question I pose is this: could both the PF and PNF, distracted as they were by so many issues going on at the time, have thought that buffet was, instead, a result of turbulence? (The same turbulence which PF was obviously so focused on prior to AP disconnect.)

rg, that's an interesting question. I surmise from three years of discussion on this topic that few to no A330 pilots have been in a training flight that included actual stall buffet. As I understand the training rig, pre stall conditions are responded to with a series of actions to prevent getting into a stall. (There is considerable merit in "an ounce of prevention being worth about 230 tons of cure" as shown by this case. :{ )

Note: If I am wrong about this training regimen, I ask the A330 pilots and trainers to correct my surmise. Being wrong is one way to learn something.

Hey rg... Any question will get you several answers here. Here's mine.

Of course the Buffet was charged off to turb, else they would have mentioned it.

Slag on, mc duff.

The rough ride - be it due to weather, stall, whatever - was sufficiently intense to alarm the cabin crew, who called the flight deck on several occasions, at 2:10:55.9, 2:10:59.4, 2:11:02.3, and 2:11:24.9, each time without receiving a response.

Lyman:
Lyman, have you taken a look at where the avionics are located in an A330? I refer to the heat producing items.
A fan motor might, but which one are you referring to? A vent fan?
Lyman, even with an uphill walk, Captain Dubois did not have an altimeter at his rest seat. He has no way to know the altitude and airspeed of the aircraft until he enters the cockpit, even though I think by this time the engines have been at TOGA (and perhaps back to idle before he returns? don't have the time line in front of me) so his aural cues might be a red herring as he heads up toward the cockpit to find out why Robert has summoned him.

He enters, and may or may not see an airspeed that makes sense to him. I am not sure if speed indications were valid or not at that point. If they were, and he's already stalled, they'd not be at values that would make any sense to a man who left the cockpit at Mach 0.82 in straight and level flight. He's got to play catch up immediately. Sadly the man who summons him is not recorded as providing a concise situation brief of "our story so far" in the cockpit.

I get the idea that Captain Dubois enters, and looks at various instruments.
He sees an airspeed value that makes no sense.
He then look at the back up instruments that are more or less in the center of the display area, and again sees an airspeed value that makes no immediate sense. (Perhaps this explains his "this is not possible" remark).

His pilot in the Right Hand Seat, Bonin, is explaining that he hasn't got control of the aircraft, that his speeds are all wrong, but I never get the impression that he gets across to Captain Dubois just what is wrong. (Since he doesn't seem to know that he's stalled, that is no surprise ...)

Dubois has to establish an instrument scan (while not sitting in his usual seat, and with airspeed indications that may or may not be reliable, and most likely are values that he finds strange) and talk the flying pilot back into flying the aircraft. (See my points to jc up there a few). He has to, since Bonin is obviously having trouble with that.

While Captain Dubois' instincts seem to be right, his situational awareness isn't matched with his situation. (I may be hanging on the "not possible" thing far too thoroughly here). He has to piece together what his airspeed, Rate of Descent, and Altitude inputs mean all while being told that there is something wrong with the aircraft by the guy at the controls.

In other words, I belive he has no idea if the crew had descended and was climbing back up as he walks to the cockpit, or if the rumbling and turb he feels is from ITCZ weather, other turbulence, or what, but I don't think his brain is associating "buffet and turbulence" with "stall." At least not initially.

He has a lot to soak up and may not actually have been utterly focused on the walk up, other than thinking
"What's wrong that Robert has called me?"
and only really gets the brain in gear as he look at the displays and has to overcome the

WTF??? :confused:

reflex.

I work under the assumption that Captain Dubois had no idea that things were AFU as he walked up the aisle to the cockpit. He had left the aircraft straight and level. He MAY have assumed that he was being called forward due to increase in turbulence. (Buffet mistaken as turbulence by a pilot who'd not been in an actual A330 stall buffet, eh?) (See notes about cabin crew reports to the cockpit).

That's my take on it, and I may be waaaaaaaaaaay out to lunch.

buffet, buzz and "touch"
 

@ RGB....

The discussion of buffet and other sensory inputs while flying a plane is very germane to this group, many who are flying to this day.

Despite all the "protections", "limits", pushers/shakers, audio warnings, etc., there is no substitute for "feeling the plane". Doze will take exception and defend the 'bus system and others, while disregarding basic airmanship and "touch" ( just poking a barb at you, Doze). I gotta tellya that if you feel something you have not felt on your thousands of hours monitoring the AP or flight director or....., that you have failed to consider the plane is not acting as it should given your control inputs or those of Otto or the cosmic FBW control laws or...

The high-speed indications for sub-sonic designs usually involve a high frequency "buzz" or vibration. You may also have aileron reversal, but this is hidden when piloting a FBW system because the system is trying to compensate and you are not directly controlling surface position, but only commanding a roll rate or pitch rate or gee. And as Doze has pointed out, we have not had direct feedback to the yoke/stick since the early 1950's for most planes using hydraulic control systems.

The high AoA/pre-stall buffet is at a much lower frequency than high-speed buzz, like 20 hz or lower. It's a "shake". Ask Retired, as his jet had a super shake, rattle and roll when getting to the edge of the envelope. The later Double Uglies had slats and much reduced buffet, but it was still there. We also had uncommanded roll when the jet was at its limits, and use of aileron was not advised due to adverse yaw and other aerodynamic phenomena. The standard procedure was to lock the stick between your knees and use rudder for roll. this technique works for the old fighters and even Cessna 150's.

The point of our discussion has to do with airmanship and knowing your plane, and it's limits/characteristics. This aspect of our discussion for two years is extremely germane to the incident and will hopefully be emphasized in training and qualification of the crews and the jet.

I think this part of BEA's final report could explain why both PNF and PF did not recognize approach to stall nor the stall itself, no?

"However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at
constant thrust. Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the
aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick.
It appears that this absence of positive static stability could have contributed to the PF not identifying the approach to stall."

Gums:

Thank you for the explanation. The only 'buzz' I ever experienced in an aircraft was on a C-130 as the rear ramp was lowered so we airborne grunts could prepare ourselves for jumping out of it!!!

Stories
 

Lyman,

Even in a Boeing, if an equipment cooling fan quits, a message such as "AFT EQPMT FAN" is generated. The backup fan would immediately take over.
The electronics bay is not really like a boiler room on a Titanic type steamer, not so dramatically hot to flush the flightdeck with a heat wave.
The BEA report has exhausted all sorts of messages from the system, and the ONLY failure that occurred was a temporary loss of accurate pitot pressures.

Change of background noise - well, open or close one of your personal vent holes for instance (no pun intended, just the little blast ports for individual convenience).

The long walk of the captain up the aisle - I believe the Air France pilot rest area is immediately behind the cockpit, where the (passenger cabin) aisle has not yet started.

Maybe this can explain why the PNF was frantically calling the captain ....

Extrait du manuel A330/340 d’AF en vigueur à la date du crash :

4.1. MANOEUVRE D’URGENCE

Elle est systématiquement effectuée de mémoire selon une répartition des tâches spécifique. Face à une situation qui nécessite de la part de l’équipage une réaction immédiate, le contrôle mutuel devient secondaire sauf dans le cas d’un pompage réacteur qui conduit à une réduction de poussée. C’est toujours le CDB qu’il soit PF ou PNF qui appelle la réalisation d’une manoeuvre d’urgence en annonçant son titre : exemple : “WINDSHEAR TOGA”.

Extract from manual AF A330/340 in force at the time of the crash:

4.1. EMERGENCY OPERATION

It is systematically carried out according to a memory allocation of specific tasks. Faced with a situation that requires on the part of the crew an immediate response, mutual control is secondary except in the case of a pumping engine which leads to a reduction of thrust. It is always the captain it is PF or PNF called the realization of an emergency maneuver by announcing its title: Example: "Windshear TOGA".

HazelNuts39, thank you for correcting me. I was under impression that 1G shake is far too excessive, yet it seems that's just what AF447 went prior to stall. I don't think such a heavy vibration can be ignored, seems that crew either totally freaked out and was unable to understand what was the source of it or somehow believed they have strayed into Cb and it was turbulence.

IMHO, magenta line on real fig 64 (report in French) makes one of the most depressing reads in the report.

That "very short time" was two hours.
Saturation was self inflicted. Had he recognized sudden drop in speed for what it was and called out UAS, we wouldn't be discussing the AF447 case any more than we did all the other loss of airspeed indication on TA Airbi. Damn it, if he only got shocked into paralysis, he would be better of.

Possibly. Maybe it goes even deeper, down to flight schools and "Principles of flight" lessons.

Thank you for explaining the way FBW works on F-16. FBW is just generic term and different FBWs can be set up in radically different manner. Compared to Viper's, Airbus' is "same, same but different". It has no G-trim, it is flightpath stable. So no need to trim it in climb or pull in turns. Stick free, it follows the flightpath.

Well... no. Aerodynamically it is stable yet with FBW intervention in ALT2 law, where low and high speed stability are lost (as is expected when there is no reliable speed measurement), it does not become neutral but unstable.

Actually, I was mistaken. It was ten times as much.

Herein lies the problem; wings design advances much faster than textbooks are updated. Boeing 757, entering service in 1983 needs mach trim. Airbus 320, entering service in 1988 needs it not. Airbus 330, entering service in 1994 does not suffer from mach buffet at all and has so steep drag rise past Mmd it is very hard to overspeed her. While AoAcrit is always affected by mach no, the effect is much more pronounced on 330 than on 320. Yet, all the time there are many airmen still learning from the books of yesteryear, unable to tell which chapters still apply and which not so they keep on seriously discussing about pitch-up of swept wings when stalled, aileron reversals, coffin corners... almost as if MiG-17 is the current state of the art.

No. It would have been an issue, if the crew pulled up, let go of the stick(s) and aeroplane pulled and trimmed into stall by itself, FBW fighting to maintain the flightpath as the airflow over the wings got detached. There is no way to check for positive static stability without controls at neutral and right stick was largely nose-up.

Cost Benefit Analyses
 

Lonewolf50
I have known some of the :mad: 'suits' that you refer to. I am willing to bet that some of them will have calculated that there is no cost benefit in more pilot training in manual handling at cruise level unless there are more than 1 crash per [name a period of time - say 8 years]. This doesn't match with the professed our first priority is safety - but they are 'behind the curtain' of the organization.

FBW laws and history
 

I shall take on Cland here, not as much for honor, but for experience and no small amount of aero knowledge for a "dumb fighter pilot".

To wit:

The normal law and the alternate laws are not "attitude" biased as one would expect in the old days of the autopilot "attitude hold" mode. The thing is programmed to hold a gee! In Normal, the pitch attitude is taken into account, so it does not try to hold one perfect gee if in a climb or descent, but whatever gee is required for the pitch attitude. So in some sense, it has an attitude function built in. Once outta Normal, it appears to be strictly a gee command with pitch rates blended. AoA seems absent to any large degree.

Make no mistake. I do not advocate the same control laws we had in the first operational FBW jet ever flown ( can't resist the plug, heh heh). A trimmed gee is not a good thing for the heavy transports, IMHO. More AoA bias seems better, but what the hell do I know.

Good observation, Cland.

About the Mig-17..... Some of my friends had the chance to fly the sucker, and it behaved exactly as expected ( there's a place in Nevada that has "funny" airplanes). Some controls had direct linkages to the surfaces ( augmented on a few), but it was honest and let you know when getting close to trouble. Funniest thing was the back stick pressure above about 4 gees - feet on dashboard and both hands pulling back, heh heh). You can ask some of my friends that encountered it in 'nam and they will tell you about how good it was in a manuevering fight, and in last year or two they took advantage of its bad characteristics.

Wrong. Aero is aero, and the FBW system can only do so much. I do not believe that the jet becomes unstable, only that there is an AoA and cee gee combo that enables it to reach a stable, stalled condition that we did not realize was possible.

All the data I have seen shows that the 'bus does not have an AoA/cee gee combination that makes the jet unstable. The intervention by FBW laws, limits, protections can only do so much. In my case, we were actually unstable until about 0.95M. So HAL took care of us, but enabled fabulous pitch rates, sustained turn rates, sustained gee and such that had never been seen.

For all:

I joined this fray to provide some perspective of FBW evolution and its good things and insidious bad things.

I respect the pilots here and hope to meet a few one time for a few beers before I pass on.

EMIT.. Thanks for the scoop. I am lookin at a schematic of the a300 E bay, and see transformer rectifiers, aC generator controls, etc. the bay is directly behind the cockpit area, and below it. I see possibilities of heat source, and so for now, I won't abandon the idea, just put Er on hold.

LoneWolf... By uphill, I mean a 15 percent grade, steeper than the steepest legal road in the US, by five percent. Yes rest is just behind and starboard of the cockpit, and when he rolled out, it would not have been airspeed he'd consider, but deck angle. At 350, a deck angle of 13,14 degrees would startle a passenger, not to mention a Captain duBord....he walks in on the crew, sees low speeds, leans against the back of jump seat to catch the angle, hears the stall SV And cricket, and says "hey, you, drop the bleep nose..."

Re BEA. One of the criticisms I have of this D- report is that too many data points are presented without explanation, not even an "unk". EG "there is a noise in the cockpit". You don't say... One is left to ponder the wisdom of leaving data in that serves only to accomplish...nothing?

They could easily include the acoustic traces of the voices, so we could see the sequence, volume, and location of the vocals....traces would not give away any meaning, but would quantify if not qualify the CVR. As it sits, there is no CVR.

Only meager transcriptions of words, no audio. So it occurs to me the BEA rejects its legal requirement to provide a report to the public. Something so heavily censored and "managed" misses the mission mark.

Captain Dubois has been hearing the continuous STALL warning since he was behind the locked door. How long did he spend behind the door waiting for someone to unlock it, we don't know, no mention of the cockpit call on the CVR ... ?
When finally he got in, the continuous STALL warning has ceased. For him the STALL is something from the past ... what's going on now that is not a stall ?

Rockhound, I noted these attempts at communications also. You are the first on this forum to have mentioned it that I have noted (but I'm presently skip-reading this thread).

This was during the initial period of heavy buffet and wing drops (not roll oscillation). It would appear there was a level of consternation among at least some of the Cabin crew.

I also wonder if there might not have been a tell tale vortex off part of the aircraft that indicated a very high AOA. Maybe the first to know they were stalled were the ones in back :ooh:, but we will never know.

Does the tailplane have buffet in Stall? Also, the airstream noise at the aft must have been very odd, and loud...the noise coming off the TE of the wings must have quite a shriek...I think lead FA was 'Mary Ann" a shame no one will know what she had to say. Probably "Not relevant to the flight". Must be quite a blow to the family, "not relevant"...

Good grief, Lyman.

Nobody that could do anything was in the rear of the jet.

The tail surfaces were probably in "clean air" due to the attitude of the jet, and had the pitch authority to get nose down attitude if only the pilot(s) tried. So I can't see any burble or buffet from the tail. AF and BEA admit that there's a "neutral" zone on the pitch coefficient curve that results in a constant pitch attitude with no inputs by the pilot. The jet still has a positive static stability, so pushing forward to overcome the control law that keeps trying to achieve one gee would eventually result in a downward vector. Let's face it. The crew did not realize that they were in a stall and may have been relying on the urban legend that "you can't stall this jet".

I can just see Appendix "Z", section "x" of the report. Before being crushed by impact forces, passenger 'X' cried out on his iPhone that unusual forces/vibrations were present due to tail surfaces in a fully stalled jet. BEAM ME UP!

I wasn't thinking the crew in back had any input at all, probably wanted to know what was going on, and then why their first comm was not acknowledged. I was thinking there were other crew besides the pilots, that's all...

Relevant
 

What she said is duly noted in the CVR transcription
(at times as noted by previous posters)

allo?

oui

allo?

Then no word, but a sound similar to one putting the phone back in the cradle

(word or group of words with no relevance to the conduct of the flight)?

Then no words but a sound similar to the ending of the cabin interphone communication

Needless to say that the pilots were to busy to pick up the phone.

Ref post 506 ..

The jet still has a positive static stability, so pushing forward to overcome the control law that keeps trying to achieve one gee would eventually result in a downward vector

This may have been one of the problems confusing PF. Static stability (which is nice to have as it feels right) is to do with stick forces rather than deflection. The basic requirement is that the pilot has to exert a pull force to maintain speed below the trim speed .. ie, release the stick and the nose wants to pitch down.

The description given is akin to neutral or negative static stability which would be quite distressing to most pilots without test experience and much more so to one with limited hands on stick and rudder experience overall, compounded by a life of watching and button pressing ..

Couldn't do much except ...:ok:

But wouldn't the Captain have noticed the sustained, unusual attitude? As the person ultimately in charge of the flight, going through the ITCZ with two youngsters up front, he could be expected to pay a bit of attention. The PNF must have thought it possible to get to the flight deck, or he wouldn't have been so annoyed they were on their own.

It appears the crew was more concerned than the Captain.

Hey, I never called you dumb... or for a moment thought you were. Actually, I find your contribution to thread very valuable.

We had this discussion before; maintaining one local gee when straight and level is consequence of chasing the stable flightpath, not the principle on which system is based. For pilot, difference is most of the time negligible.

Sorry, I have mistakenly believed you have referred to the part of the final report pointed out by Retired F4 and rgbrock1; that FBW makes the Airbus behaviour slightly unstable by maintaining the flightpath with the speed changes while you were talking about post-stall stability. Flying at such a high AoA was outside the certification scope, as it is assumed that pilots will recognize the stall promptly and initiate the correct recovery action so no one has ever tried to reach extreme AoA in test flight. However, from DFDR data it can be seen that aerodynamics were not enough to keep AF447 stalled; at about 2:11:45, THS is winding up and is 2-3 degrees shy of full nose up, elevators are fully nose up, as trust levers get retarded N1 goes down and nose drops from +15° to -10°.