RetiredF4

No, i´m picking up some popcorn, looks to be lots of fun when you take it up with OG on the matter of aerodynamics

Owain Glyndwr

I take it you don't mean us to take reciprocal literally? Complementary perhaps?

Again, not quite - normal acceleration is just as important

There I don't agree - adopting a default value for the stall warning AoA threshold for use when a genuine Mach value is not available does nothing to limit the pilot's authority. It might let him go further into buffet before calling halt at high M and be more restrictive than it need be at low M (until flaps/slats are extended, at which time it can be made indistinguishable from the value it would have if Mach were available), but it would certainly give better guidance than they get today.

PS: It's getting late and I need to check, but I seem to remember that the stall warning AoA already defaults to something like 10 deg when no Mach is available (Hazlenuts?)

HazelNuts39

BEA's 2nd interim report, page 47: There is another "backup" value of 8.6 degrees that is used when all three ADR's are lost (or switched off to get the BUSS).

P.S.
On page 20 of IR#3 BEA notes that the decrease in speed corresponding to an increase of 1° in the angle of attack depends on the flight conditions: 25 kt in cruise vs 5 kt in Takeoff/Approach. It is interesting to note in the following chart that the difference near the stall warning threshold is much smaller: 9 kt at FL350 vs 7 kt at sealevel.

DozyWannabe

Understood - in my defence I never said it would be useful for airline pilots, it was just to demonstrate a relationship existed in a theoretical sense - Aerodynamics 101 in other words.

I remember it well because it was what had me go look it all up and try to understand it in the first place!

My own copy of HTBJ (which sits to my right as we speak) was bought as a result of that conversation.

To be honest I think I'm going to have another breather for a bit - but you have my gratitude for the pointer and advice and I will get around to it.

Actually it's more a discussion of algebra (which I admittedly find difficult).

They act in a reciprocal manner - I've just realised that the term "reciprocal function" has a definite meaning in algebra - oops. (told you I found it difficult!)

Perhaps I should have been clearer - I was referring to gums' idea of a low speed protection based on AoA alone.

Before I bow out for a bit - one of the things that puzzled me coming out of the sim session was that the A320 in Alternate had a definite hard limit on autotrim, which doesn't seem to have been the case for the A330 - I wonder why that is?

CONF iture

AZR,

I do appreciate your sane honesty. That’s not a given to all …

As you mention Habsheim, just a quick word to say that Alpha Max was never reached. But I don’t wish to discuss that thing here. As mentioned earlier, I will start a thread on it and it will be a pleasure to possibly debate then.

Merci

DozyWannabe

Well let's be fair here - I never disagreed with what you were saying in the first place regarding Alpha Floor, but you elected to give me grief over it.

Well no - Alpha Prot has a small margin added (to account for wind fluctuation and the like). But even if that margin didn't exist there wasn't enough airspeed to get them over the trees.

AlphaZuluRomeo

CONF iture:
Thx. It was no so a misconception than a miswording, nevertheless "Errare humanum est, perseverare diabolicum" and I try to remember that, sometimes.
I edited my #932 accordingly.

Indeed, Alpha prot/max/floor don't belong here (AF447), will wait about your thread and will be happy to read it, and participate if I feel it useful.

Ian W

From DozyWB
Dozy,
I know this is late - but you really should have looked at turbulence as it occurs in the Inter-Tropical Convergence Zone. These are not weak mid-west thunderstorms - but a LOT more powerful:

"ITCZ thunderstorms are slightly different from midlatitude storms. The differences are primarily due to the different atmospheric conditions in these 2 locations. The strong thunderstorms we endeavor to avoid in the midlatitudes are often due to 2 distinct air masses lying on top of each other.

PJ2

Ian W;

While I agree with all that you say regarding the ITCZ, the key, (and I know you and many here, know this), is vigilance and avoidance, regardless of route.

The thunderstorms in northern Canada differ markedly from those in the Caribbean and while one gives those in the Caribbean (and the ITCZ of course), more berth, both are avoided with as wide a margin as possible, commensurate with one's clearance, (to be clear, it is rare that the emergency authority of the commander must be used to deviate from course or altitude without a clearance).

The circumstances where one has no options and must pick the best route out of a number of equally bad choices are rare but they do occur.

The primary defence against surprise is the constant and knowledgeable use of radar for as long as necessary, bearing in mind two facts about the return signal - that it is moisture that returns the signal* and that TCu's can be hidden from radar by stronger returns closer in.

On June 1, 2009 on the first thread (before it was quickly closed, as it should have been!), and based on experience as well as what Dave Gwinn (RIP) has had to say on radar tilt management (among many things he's said), I posted some comments on the use of radar. I believed then as I do now that the use of radar was not well understood and is poorly taught to airline pilots who must get their knowledge informally as well as through manufacturer's brochures. I think airlines just assumed that "pilots knew", just as they assume all their pilots understand a bit about high altitude, high Mach Number, swept-wing aerodynamics. The one superb source on the intelligent use of today's radar was Dave's work who has written. Along with Trammel's work, at the time it was the best information available. In keeping in touch with what some airlines are doing, I see that much more information is now available in FCOMs. PPRuNe is a good source, as always.

In my experience with the ITCZ there wasn't always a way to avoid all weather so one picked one's way using radar for long-term planning, (A330/A340 radar - 160nm scale, varying tilt to take slices, making calculations of height, watching the changing picture, changing the gain but staying mostly on AUTO), and by watching outside for possible routings. Turbulence was a regular occurence and occasionally long-term characteristic of flight through the ITCZ (Pacific). Sometimes we'd get hammered, very sharply, sometimes when we expected to get hammered the ride was smooth. Diversions were routinely done.

The introduction of CPDLC was in my view a tremendous safety enhancement for such diversions and altitude changes.

Regarding AF447, it is difficult to come to any solid conclusions regarding their choice of routing. They did discuss altering course and indeed did so to the left, without an ATC clearance. In my view the turbulence indicated in the data was not unusual, (1.25 to 0.8g).

To my knowledge, the notion of sleep inertia on the part of the PF has not been widely discussed but the UAS event occurred within about ten minutes of the call to the flight rest where he was sleeping. It will be interesting to see if the Final Report addresses this issue, as it is a known human factors matter.

gums

I have to note that my own experience with CB's in the tropics was that they were no where near the stuff I experienced in the U.S. mid west.

Hell, we even refueled in a thunderstorm on one ferry mission over the Pacific. Great boom operator and we could hold position within 10 or 15 feet.

The U.S. mid west CB's routinely go up to 40,000 or 50,000 feet, and tornadoes are common. Then there's the mountain wave CAT if you are flying over Kansas or Nebraska.

As with PJ's observation, we used our attack radar to tilt up and down to see how high the CB's went. Then turn left or right to minimize problems.

In the final analysis, I don't see the choice of routes as the primary cause of the crash. out......

mm43

It was the PNF who said he had dozed and returned to the cockpit at about 0200 and took the LHS. The PF had been in the RHS from departure Rio de Janeiro. Your comment regarding sleep inertia is still relevant as it could well explain the PNF's lack of positive action over the next few minutes.

Lyman

I think it quite possible PNF had not "cleared the cobwebs". If so, it may have played a major part in his reluctance to immediately gain control from someone who had been in the cockpit for the whole time. PNF had several things on his mind, including a vague command structure left by the Captain?

CONF iture

More than anything, IMO, the PNF never handflies from the left seat, why should he suddenly feel comfortable to manipulate the stick from that side ...
His job was to monitor and call the deviations, in this case : PITCH - WATCH THE ALTITUDE - PUSH in order to give a serious hand to his partner. Calling the Captain back was not the priority.

jimjim1

I have the idea that the PM had a very good idea what was going on but for whatever reason he was content to watch as the pilot flying manoeuvered both of them to their deaths. + 100's of others of course.

I think it was a matter of seniority.

Obviously the PM was not exactly content to die, however, I think that he did not have the bottle to avoid it.

All he (PM) could think of was to hope that the Captain came back to save his life.

Sadly his (PM) hope was misguided. It appears that the PF was determined to ignore the PM's opinions regardless of the consequences.

Old Carthusian

It would be a bit risky to attribute the PF's failure to respond to the PNF as a matter of deliberate will. It may indeed have been that way but we do not have the information to back up this supposition. Just as likely was that the PF went into a state of shock and couldn't process any of the information directed at him by the PNF. We just don't have the information to form a conclusion one way or the other.
Rather it is worth focusing on the lack of professionalism in the cockpit. None of the crew can be said to have responded as one might have expected well trained pilots to respond. Clandestino's reference to the article 'Who killed MacMillan' is I think rather relevant as it illustrates an organisational structure which allows this unprofessional type of approach to develop. Airlines which seem to have developed this condition would seem to include Air France and indeed their own safety audit referred to similar issues. I am not convinced that this crew was professional and therein lies the key to this accident. But I would hesitate to ascribe a level of deliberate behaviour to the circumstances of the accident.

PJ2

mm43;
Thanks! Yes, it was the PNF. I should re-read all three reports to refresh my memory of these things.

Not to divert discussion but I think sleep inertia has not been sufficiently addressed as a long-haul/ultra-long haul matter. It is not just a crewing matter, (as in crewing with four pilots vs three, etc).

I think sleep inertia was at work here. Along with the usual examinations of the crews' activities & sleep patterns prior to the cycle and during the layover, this phenomenon needs more focus in this report as well as generally in research.

The 2011 pitch-down incident involving a B767 on the Atlantic is enough to cause wider examination of the matter no matter how caused of course, (bunk time or controlled rest on the flight deck).

The issue has been demonstrated and airlines can no longer ignore its effects.

PJ2

O.C.;I think so. First, these days it is highly unusual to experience a serious abnormal and even more rare to experience a full-blown emergency.

With 2900+ hrs TT and 807hrs in the A340/A330, (216hr on type), the PF almost certainly will not have experienced a significant failure with full application of adrenaline. Many will go an entire career without it, so highly-successful are the historical and present technological solutions to the safety of flight.

So while the sim recurrent work will have covered the abnormals and emergency procedures for these aircraft, most transport pilots here likely including yourself OC, can tell us that when they do occur, an inflight abnormality or emergency places psychological demands on one that cannot be experienced or taught in training. An abnormality requires significant self-discipline to collect and order one's thoughts and actions. And each person has slightly different responses in such circumstances which is up to CRM to sort out and quickly make a "fighting team", as it were, out of two cockpit crew on a routine mission.

We cannot look to individuals for what we may now consider as "their lack of experience", as every one of us who fly or used to have been there too. We cannot give a course in "More Experience". I think you have expressed it well. We have to look more broadly, which is one reason I considered broaching the sleep inertia matter. We can examine SS vs CC, last-remembered actions for an after-takeoff UAS drill, training, training records, script priorities, airline culture and so on. There are other matters that we could name. The fact is, the accident did occur when in 30+ UAS events it did not; Why here? If factors which are identified as primary and those that are categorized as contributing are fixed, where, in human factors especially, must we look towards next?

Old Carthusian

Sleep inertia as a possible factor in this accident I think has considerable merit. Looking at how people function when they are sleep deprived does throw up interesting parallels with what we know of the reactions of this crew. It does tie in with the professionalism issue and here I should stress that I am not using professionalism as a value judgment but as a being able to act so as to provide the best possible set of responses in any situation. This issue is cultural but I don't think can be directly taught either. A pilot has to want to follow his exemplars and be like them. Any pilot needs to be aware of all the factors that might limit his/her performance and how to mitigate them as much as possible.

jcjeant

A quote from the explorer Amundsen:
Victory awaits him,who as everythings in order.
Luck we call it.
Defeats is definitely due for him,who has neglected to take the necessary precautions.
Bad luck we call it.

mm43

As Human Factors are bound to be an important feature in the BEA's Final Report, consideration should be given to which particular disfunction will dominate.

In Post #27 AF447 - Thread No.6 there is an interesting link to a study on how people adapt to taking manual control when the automatics give up, and more.