DozyWannabe

I'm pretty sure that's not the case - to the best of my knowledge the annunciator system is separate from the flight control logic. The Control Law logic itself is triggered by failure detection scenarios between the sensors and flight control computers. It should not trigger when one of those sensors records something outside of the envelope, only if there is a confirmed failure of one of the systems.

In short, in the unlikely event there's a failure of the system and a concurrent entry into stall warning territory, then the control law will degrade, but a value that triggers stall warning by itself will not trigger law degradation as long as the system checks out as operating normally.

HazelNuts39

In the QF72 accident a faulty ADIRU emitted erroneous data for various parameters. The crew received stall and overspeed warnings, the protections responded to an erroneous AoA value by pitching the airplane nose-down, but Normal law was maintained.

infrequentflyer789

@retiredF4, dozy, hn39

I checked, I'm wrong you're right.

Should re-read and revise before posting rather than rely on memory.

Perpignan also stayed in normal for ten secs or so during SW, before other parameters kicked it out of normal.

DozyWannabe

Remember that the root cause of the anomalies at Perpignan were damaged static ports caused by improper maintenance procedures during cleaning. The level of systems issues caused by loss of valid static information is considerably more severe than those caused by loss of pitot tube data (e.g. comparison of Birgenair 301 [pitot] to Aeroperu 603 [static]).

mary meagher

Reading the recent comments, I am struck by how quickly the nose up Airbus lost altitude, with less than 90 seconds available to recover from an initial altitude of - was it 38,000 feet? It calls to mind that early display when an Airbus planked into a grove of trees when the engines didn't spool up quickly enough....in that case did the protection prevent the stall?

DozyWannabe

Yes, and it's likely that the death toll was significantly reduced as a result.

In a more serious setting than an internet forum, a statement like that would be borderline slanderous. Do you have any evidence for this supposition? Or is it more likely that they *did* analyze the technical aspects and found that no technical failure matched the evidence?

I've asked before and I'll ask again - I can't see any benefit to the BEA by smoothing things over for Airbus. It would also open Airbus to greater risk of problems if the issue repeated itself. What do you believe either would stand to gain?

jcjeant

No technical failure (exept pitots of course) was early announced by Airbus after a BEA note (if I remember well ) released around 27 May 2011

DozyWannabe

@jcj:

Well yes - that does not mean that potential technical failures were not considered prior to that press statement however. We know they brought up the avionics compartment - all such a statement would mean is that they didn't find anything wrong besides the pitot tubes. It doesn't therefore follow that they didn't check.

What we do have is:

• The PNF calling out "Alternate Law" - which means ECAM was working
• The Captain indicating all three ADIs (horizon) - which means they were working
• Multiple altitude call-outs during the descent - which means the altimeters were working

This would seem to indicate that the idea they were in a dead flight deck with no displays is a non-starter.

bubbers44

I don't care what airplane you fly but if all your airspeed went away in the clouds with a little turbulence and everything else worked like altimiters, VSI, attitude indicators and engine power indications would it be a major problem? I didn't think so. Why them? Hands on flying maybe?

Lyman

Doze...

This.... In short, in the unlikely event there's a failure of the system and a concurrent entry into stall warning territory, then the control law will degrade, but a value that triggers stall warning by itself will not trigger law degradation as long as the system checks out as operating normally.

At what point then do you consider the a/c STALLED? It changes LAW to accommodate the STALL? How tight does Mr.Pilot have to play it? Should he wait, so that Mr airbus can still claim, "Won't STALL...." In Normal Law

Here....

The PNF calling out "Alternate Law" - which means ECAM was working
The Captain indicating all three ADIs (horizon) - which means they were working
Multiple altitude call-outs during the descent - which means the altimeters were working


No, he may have called Alternate Law because he knew without speeds, Normal goes away

Probably, but you still have to admit, they may have been working, and wrong....

Multiple altitude callouts. from Altimeter? Again, working and congruent, but....

And In a more serious setting than an internet forum, a statement like that would be borderline slanderous. Do you have any evidence for this supposition? Or is it more likely that they *did* analyze the technical aspects and found that no technical failure matched the evidence?

The St Elmo's fire is not analyzed, the PNF statement is given as "Proof"

The additional heat in the cockpit is not enlarged,

The Smell is allowed to be proven by PNF again, a known authority on Nasal powers...

"What's that". Again the proof is a good guess...

An analysis of prior events re: no record of RHS....


BEA is relying on PPRUNE to vett their analysis. I think their ploy was a good one...

One gigantic leap of faith in an audience that will accept wool as an eye covering...

DozyWannabe

Lack of high-altitude manual handling training is almost certainly a factor, but the sad truth is that no matter how good you are, sometimes it just isn't your day.

The kind of Stall Warning I was referring to was a transient warning - on the order of a second or two at most. In such an instance the aircraft is not stalled and is not in any danger of stalling, but because of the pre-emptive nature of the warning, it sounds regardless. In many respects it's like the "G"-induced warning that sounded after the PF pulled the nose up to 15 degrees - the aircraft was actually a long way from reaching approach to stall, but because of the abrupt shift in data the warning sounded. Surely in this case it's better to design the systems to be over-cautious rather than the opposite?

Highly unlikely - he was monitoring pilot and knew to go to ECAM at the first sign of a problem. Given that he did not immediately take control away from the PF in light of the inappropriate attitude, it's probably reasonable to assume that he was not especially well-versed in the consequences of a drop to Alternate.

The chances of that are exceptionally slim given the evidence at hand.

Lyman

Ah, the STALL warning is explained...


"No Harm, No foul..".


Really? Transient... K.......

The first Stall was real... And transient. "Oh oh where's the Stall bug?" Your readiness to dismiss the Warning is presumptuous, no offense. If I hear the Stall Warn, and I no longer have a Vsw prompt, well, I may be concerned. Perhaps especially if I fear Overspeed at the same time, as has happened before?

The explanations are long, and legend, with precious little concurrence even between and among the pros?... The pilots had seconds... Are you not a little embarrassed?

DozyWannabe

The first warning was not. This is not coming from me, this is coming from the TRE on the sim day, who was well-versed in the event.

Hey, I'm just repeating what I was told by a veteran pilot. And the evidence indicates that the actual AoA of the aircraft was not consistent with stall at that point.

Actually, most of the "pros" that I trust tend to agree on the issue.

CONF iture

Remember to read one more time the report before spreading more erroneous information.

CONF iture

Is it again something of your own making or you will produce a Reference this time ?

CONF iture

Who's talking about technical failure ?
As designed, the autotrim helped to put deeper the aircraft into the stall ... Which manufacturer would like to see such brilliant design discussed widely on the public place ... ?

CONF iture

The first warning was real and should have been longer, dixit the BEA.
I thought your faith in the Institution had no limit ... but now a 'veteran pilot' would make you doubt ... ?

Organfreak

Lyman blurted out:
I'm sorry, but..................

ROFL!!!

IcePack

I've always thought Airbus speed indications to be very sensitive.(almost like the hole in the front of the pitot is too large) so the sudden onset of turbulence would give very rapid reading changes. Interestingly we got into some rough stuff (a320)at 37000 over the alps the other night. Air speeds were fluctuating rapidly+15 to -25 kts, with the speed trend arrows going off the scale. Whilst the auto (guidance) pilot stayed engaged and auto thrust did not chase the speed.
But whilst the turbulence was quite sharp edged I would say only moderate but the speed indications would have had you believe the aircraft was out of control. Obviously it was not but the speed indications looked horrendous / stupid. In my mind this would have added the confusion to the crew after the uas event.
(note I have more hrs on Boeings product than AB ( quite experienced on both )), & find the Boeings airspeed indications more damped than the AB)
Whilst 16 pitch at height would look totally un-real I suspect this crew were totally confused by ALL the indications & warnings. Imagine the Capt coming back in and seeing hearing all that, would he as well be confused thinking 16 up going down noise warnings coming & going that can't be right "what has happened to the flight instruments they are reading crazy they must be at fault."
Humans are not good at multiple shock analysis coupled with fear & sceptasizm.

DozyWannabe

My mistake - it was water from the cleaning freezing inside the AoA vanes. I'm sure I remembered reading "static port" in Flight or something though...

I believe the old Approach To Stall procedure was in the FCOM Supplementary Procedures - not an ideal place for a memory item, certainly! I have it on good authority that the new procedure has been added to the QRH.

Are we talking about the same warning? I'm talking about the single "blip" on the traces at about 02:10:08 - that was a single "G"-induced warning, and the aircraft was not about to stall at that point. The first non-transient warning (where the aircraft was actually approaching stall) began at approx. 02:10:48 according to the traces.

You clearly don't know me well - it's not about having "faith in [any] Institution", but a desire for factual accuracy and an intense distaste for politically-motivated conspiracy theories.

The BEA's only job is to establish the relevant facts - you can bet that one of the ambulance-chasers will try to make hay out of the autotrim feature. After all, the biggest source of misinformation as it applies to aviation accidents tends to come from lawyers releasing scuttlebutt to the press.

And yes, I'll take a veteran pilot's word, but not if they're irredeemably arrogant (Asseline) or clearly delusional (Jacquet/Marnet-Cornus).