thermostat

3holelover, I agree with most of what you say. I will go a step further by saying that part of airmanship is not to fly a heavy airplane at high altitude near the coffin corner, through Cb's. I get a kick out of the entire discussion about different "laws" and how to recover from a high altitude stall etc. etc. when this whole thing could have been avoided by diverting around the storm. That simple !! It's unbelievable how much this thread has gone off on a tangent to somehow blame the 'plane or the lack of knowledge in high altitude stall recovery. And one other thing. It wasn't ice crystals that caused the pitot blockage, it was supercooled water which froze on contact with the pitots. That same SC water would have made the AOA vane inoperative also. It would be helpful if we could stick to the real facts in all discussions. Just stay away from CBs at high altitude. End of story.

Mad (Flt) Scientist

Since AF447 HAD AoA vanes, and they actually continued to provide good data except when invalidated by the system due to low airspeed, how do you conclude that the AoA vanes would have been inoperative? They were in the same atmospheric conditions as the pitots. The pitots couldn't cope, the vanes did.

mm43

No! AoA Vane #1 was having a 'rest' well before the AP disconnect.

TJHarwood

I respectfully submit that the very length of these various threads on AF447 in itself indicates a widespread enough fear in many quarters that other high altitude UAS events on various aircraft could all too easily end equally fatally (under circumstances identical or very similar to AF447).......

rudderrudderrat

Hi Clandestino,

The most important warning on that flight deck was "Stall Stall" - which appears to have been ignored / not acknowledged / not heard. (Similar to the You Tube "What's that Beeping?")

If their human auditory channel was filled to capacity with previous flight deck audio noises, (Cavalry Charge, ECAM Dings, ALT Alert etc), and the crew are attempting to verbally communicate whilst they trouble shoot - what is the point of having the only stall warning alert simply another verbal "Stall Stall"?
Even my iPhone has both audio ring plus Vibrator to get my attention.

Do most other aircraft have a stick shaker as a stall warning? If Apple can fit one into my phone, why was it not possible to fit something similar into the side sticks?

Before AF447 event, there was NO Stall Warning QRH procedure. The previous procedure was buried in FCOM.
The new QRH procedure emphasises reducing angle of attack, and does NOT recommend the use of TOGA power. (as the old FCOM procedure did)

BOAC

- not a complete picture since the 'cessation' of the warning was recognised? Time to think again.

Clandestino

Shakers are installed if natural pre-stall buffet is too weak to be recognized (or non-existent). I hope final report addresses whether the Airbus got through certification too easily or FBW Airbi indeed have sufficient natural buffet to warrant omitting the stickshaker. I agree that with sidestick, effective shaker needn't be much larger than those used on modern cellphones.

All transient and not going off simultaneously with stall warning. IIRC even if they were trigered simultaneously with stall, stall warning overrides all other audio alerts.

Same way that you recover from mid or low alt stall. Hint: therr's difference between approach to stall and stall itself, which is seldom appreciated on PPRuNe.

If this theory is congfirmed by HF group, that would show complete incap on the PF side. Unstalling by pull? Only when flying inverted or you're doing some very serious aerobatics.

Because it was assumed that pilots understood stall & recovery from day one and never forgot it. Whooops.....


Little less respectfully, I offer alternative explanation: as usual, fatal accident wakes many up to the reality of aviation being a very hazardous game. Length of the thread is due to inability to lay our fears to sleep with usual lithany of "It was only loco/Africa/Russia/Asia/Latin America/cargo anyway"

rudderrudderrat

Hi Clandestino,

Then why did the QRH have "EGPWS ALERTS" in the Emergency Procedures?
Using your logic - you would think that "Pull Up" before hitting the ground and apply TOGA power would be instinctive - so why include that one?

I think Airbus believed they had designed an aircraft that was so well protected and that the chance of stalling was so remote - that a Stall Warning QRH procedure was deemed not necessary.

With the benefit of hindsight - that has now been fixed.

You'll find that every Boeing & Lockheed has a dedicated stall warning stick shaker.

Old Carthusian

You'll find that every Boeing & Lockheed has a dedicated stall warning stick shaker.

Which can and has been ignored by pilots. It is important to remember that this is not an accident related to the aircraft configuration. It is an accident related to aircrew behaviour.

Ian W

Which would appear to be a trained and ingrained 'by rote' behavior with little actual practical follow-up training.

Diagnostic

@Old Carthusian:
All very true, sir.

However, in the spirit of trying to close as many holes in the proverbial swiss cheese as possible, I see no harm in at least considering whether stall warnings via a different cognitive route (i.e. non-verbal, non-text) might be helpful - although as you say, also not perfect.

In the case of AF447, the question in my mind is whether the stall warnings were (a) not heard (e.g. cognitive overload or similar) - perhaps stick shaker would help here; (b) heard but not believed (due to multiple apparent problems with the aircraft behavior, leading especially the PF to ignore all warnings?) - stick shaker might be ignored in this case too!; (c) some other reason.

Personally, I fear that the answer is (b) but of course, I don't know. I think that rudderrudderrat has put forward a very good case for auditory overload (also Ian W) - I know that when I'm trying to speak to someone, I do tune-out all extraneous sounds; I can't tune out only selected sounds unless one sound is especially loud. So perhaps the answer is (a), and for that reason shouldn't a stick shaker be considered, for those occasions when it would help?


@mm43:
I mentioned this a few weeks back, and sensor_validation kindly pointed out a very plausible potential cause (link below) unrelated to ice (I don't know if that's what you were suggesting?):

http://www.pprune.org/tech-log/45687...ml#post6628318


@TJHarwood:
I also thought you were right. I was only replying to (what I believe) Clandestino was saying, where he seemed to be saying that if 32 other crews could manage clogged pitots successfully, then AF447 was the exception. The reason I posted was that this assertion seemed to conflict with the data & analysis presented in the 2nd Interim BEA Report (which I found very interesting, as it touches on some aspects of my professional life).

If I misinterpreted what Clandestino was saying, and if everyone agrees that some of the other 32 incidents were also (or could, in other circumstances like in turbulance, at night, at FL350, have developed into) "close shaves", then I happily withdraw from the conversation for the moment.

Mad (Flt) Scientist

Actually, I think they (and others) took the position that not only was it not necessary, it was actually prohibited, at least from the flight manual.

The idea that you recover from a stall by pushing the nose down was felt, at least by some, to be such basic airmanship that it was actually prohibited by regulation from inclusion. Airbus were not alone in having no such procedures.

steamchicken

That's really impressive data visualisation - brings out the difference between the PF and PNF's responses and also the dual input events.

(A thought - when we want to focus on the trend in a particular metric, we plot it on a chart like the DFDR traces. Strangely, aircraft displays show scrolling numbers or else multiple needles. Would a "value plus trend-line" be better? Medical monitoring displays do this.)

DozyWannabe

My wild-assed guess in this situation would be that stall recovery is taught in single-engined trainers from very early on in basic aircraft handling training. Most single engined trainers are not equipped with EGPWS.

Well, it's an opinion with merit in a theoretical sense, but I'd be surprised if that tured out to be the case. I remember reading an interview with a pilot in "The Tombstone Imperative" in which he advanced the opinion that things like stall recovery and microburst recovery have been mitigated by the arrival of the large high-bybass turbofans that were introduced with the widebodies and were installed on every new jetliner from the mid-70s onwards - you could just apply TOGA and keep the wings level and the AoA within a certain range and power out of it. It now appears that this is not always the case.

What makes your assertion doubtful for me is that if Airbus truly ever felt that way then they would not have put a stall warning in the aircraft in the first place - yet they did. So from an engineering perspective at least, Airbus always knew it was possible.


So did the VC-10, BAC 1-11 and HS Trident - in fact they pioneered the technology. However, as D.P. Davies said in the third and final edition of HTBJ, pilots had trouble trusting them and adjusting to their presence. Stick shakers in the Trident, 727, 757 and MD-80 have all been ignored on the line with fatal consequences.

As to the other discussion, the presence of supercooled droplets in the area AF447 flew through is debated. Even the BEA won't put the pitot failures down to anything more specific than "ice crystals".

jcjeant

Hi,

DW
Incorrect
This is a mandatory specification from regulators .. nothing to do with any Airbus decision.
As for a Airbus be able to not stall .. it's true .. for Airbus Industrie (or EADS)
This is black on white from Airbus
No training necessary for stall condition
This is one of the point in their commercial incentive ... low cost training

Note (from BEA report N°3 page 63)
Before this date .. Airbus don't write about "Stall recovery" .. but instead .. "Stall warning"

And this is the change made after the AF447 accident (BEA report N°3 page 82) for the simulator training

Yet .. nothing about training for stall recovery ..........

Ice crystals ? .. well I wonder what can be a training in flight simulator for "ice crystals" ....
A employee of the training center trowing ice crystals on the simulator casing ?

I am almost certain that these new workouts are not going to make more significant progress in terms of flight safety.
Only the real flight training will provide pilots with the mastery of certain events
More flight simulator training for this kind of event it's just like put a additional (redundant) fire alarm horn near another instead construct more fire escapes
You can't save lifes with a supplementary horn .. you can just spare money for short term .. but problem not solved (I was there)

CONF iture

Then stick to your words, concentrate on the facts and give a break to your snobbish and pompous style, that won't hurt.

Basic rule : Do not put words in my mouth or assume by quoting me if you pretend I have said so ...


I would rather think, according to the serial number, that F-GZCP was the Enhanced version of the 330.
I believe airfrance has or had 16 A330, 4 of them being A330E.
F-GZCP was also the newest in the fleet.

As you may have more accurate information ... please, let me know.

mm43

Well it could be related to ice, or it could be related to the EASA AD, and there is no way of proving it now. Though looking at the traces (when valid), it was tracking again prior to 2:12:20.

In any case, it wasn't an issue in ALT 2B as the SW used the highest AoA value.

DozyWannabe

Air France F-GZCP (Airbus A330 - MSN 660) | Airfleets aviation

F-GZCP was an A330-203. As far as I know, they didn't retrofit design changes from later models to later production runs of earlier models because of the training issues that would ensue (pilots reported a significant difference in feel between the old system and the new). So for the moment let's assume that F-GZCP was of the old design when it came to the rudder controls. Either way I don't think it matters a great deal regarding this accident because the rudder barely came into it.

Still waiting on your reply on the other thread by the way...

Diagnostic

@mm43:
Agreed, sir - my point is just that we do have another plausible potential reason, and so I don't think we can say the AoA vanes (specifically #1) were definitely affected by ice.

I'm interested - other than the Perpignan incident (where the AoA sensors had been "abused" outside their specs before the flight), is ice affecting AoA sensors as much of a problem as pitot icing?

Svarin

DozyWannabe dared writing :

Read the report in full, including page 1xx where you will find the rudder traces. Just because BEA did not expand on the subject does not mean it is irrelevant.

You yourself have used the expression PIO (which stands for Pilot Induced Oscillation). Experts now prefer APC event (Aircraft Pilot Coupling), which better emphasizes the interface issue. There is a definite APC event in this instance, in roll and yaw. Rudder played a huge part, as a fast-moving, oscillating control surface with zero feedback to the pilots.

Regardless of what actually caused these oscillations, and why did PF had such trouble keeping the ship's wings level, rudder certainly played a major part in the whole sequence.

That the system governing this particular control surface was subjected to a large update is in itself source of questioning.

Yes, looking at the traces is dull work. But as long as we take these recorders for the truth of the matter, the traces are all we have as unbiased data, along with the ACARS messages. Unless one is prepared to use and study them carefully, one can only follow pre-made conclusions written under careful supervision by interested parties. Such should not satisfy an inquiring mind.