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-   -   AF 447 report out (https://www.pprune.org/rumours-news/489790-af-447-report-out.html)

RetiredF4 3rd Oct 2012 21:34


DozyWannabe
No - the PDF links contain the "at take off" and "phases after take-off" actions. It is the latter I have quoted. One does not maintain altitude by maintaining backpressure on the stick/yoke - if the aircraft is trimmed correctly then no direct input is required.
You assume, that one trims into stall, therefore no backpressure is needed when speed decays? Or you are talking about an aircraft, where autotrim is keeping the aircraft trimmed into the stall?

Actually i think the procedure "reduce pitch" refers better to situations, where the aircraft is not entering the stall due to decaying airspeed in straight and level flight, but due to loading the aircraft while maneuvering, like initiating a turn or a climb (we called that accelerated stall).

Reducing pitch (for avoiding stall) in straight and level flight would be better expressed by stick / SS push forward until stall warning stops and would cover the other situation as well.

Lyman has half of my point.

DozyWannabe 3rd Oct 2012 21:44


Originally Posted by RetiredF4 (Post 7447882)
You assume, that one trims into stall, therefore no backpressure is needed when speed decays? Or you are talking about an aircraft, where autotrim is keeping the aircraft trimmed into the stall?

Neither - I'm simply stating that none of the procedures refer to backpressure on the stick. Because no matter how you get into the stall warning regime, pulling back is almost exclusively the wrong thing to do.

truckflyer 3rd Oct 2012 21:50

"DozyWannabe" - That was based on the channel 4 program.

Now I have not checked the official transcript, channel 4 translated this from French, so I do not know of the accuracy of this. I would assume they would use original transcript/translation.

DozyWannabe 3rd Oct 2012 21:53

They used a combination of the BEA transcript and Otelli's from what I could tell. I watched it and must confess I can't remember words to that effect, but if I can find it on 4oD still, I'll have another look later in the week.

RetiredF4 3rd Oct 2012 22:05


DozyWannabe
Because no matter how you get into the stall warning regime, pulling back is almost exclusively the wrong thing to do.
Fully agree, i would not have commented on such a statement.

But..


One does not maintain altitude by maintaining backpressure on the stick/yoke - if the aircraft is trimmed correctly then no direct input is required.
that statement in discussion of a stall procedure is misleading.
I give you credit that it was not intended though.

DozyWannabe 3rd Oct 2012 22:27

@franzl - No problem.

Note that the first action in the Stall Warning list is to set thrust to TOGA, which will give you a nose-up tendency anyway. In that case, maintaining altitude would be better served by pushing the stick ND.

truckflyer 3rd Oct 2012 22:39

Checked the BEA transcript, nothing there, however it was mentioned on the Channel 4 program, so not sure if this is their "imagination"

I recently completed TR on A320, and we did do some stall practice, and was told first action now was stick ND - and than after TOGA!
I was told this was something that had recently been changed.

DozyWannabe 3rd Oct 2012 22:43


Originally Posted by truckflyer (Post 7448011)
I recently completed TR on A320, and we did do some stall practice, and was told first action now was stick ND - and than after TOGA!
I was told this was something that had recently been changed.

Yes. Until recently the onus was on "Approach to Stall", which involved maintaining pitch to the best of your ability and cramming on the power at the first sign of stall warning. Actual stall recovery would not have been trained.

truckflyer 4th Oct 2012 09:23

Actually you should not even use TOGA now, progressively increase thrust as required, after ND with the stick, to get you out of the stall.

It does seem in the start they believed the instruments, than they came to a stage of disbelief!
Did the PF have a panic attack, holding the stick back without being aware what he was doing?

As these stories are told, documentaries made, it is difficult to know what is the exact events, as sometimes things are omitted or added for effect of "entertainment" or creating a story!

But the main focus what I have heard from other pilots that I know personally, friends of mine, is that the captain should never have left the cockpit for his rest at the time he did. All I spoke to said they would never have done that!

Lonewolf_50 4th Oct 2012 12:39

truckflyer:

If you have the stomach for it, you'll see about every angle possible of the debate on this accident covered in fine detail in the discussions that began here in JUne of 2009, shortly after the aircraft was lost.

Any number of pilots who have actually flown the ITCZ routes do not agree with your point on where rest is, yet others do.

Best wishes on the reading, there is some good info and some good commentary, surrounded by no small amount of chaff.

jcjeant 4th Oct 2012 23:04

There are disturbing similarities between the drama of the Titanic and AF447

Popular
"best machines" that human kind can construct (high technology concepts)
Titanic
Reputed as unsinkable because protections (watertight doors)
AF447
Reputed as "can't stall" because protections

Titanic:

1-They know (have warnings) of many ice and icebergs in the vicinity
2-They know (seamanship) that it's necessary to reduce speed
3-Captain Smith is not in the wheelhouse

AF447:
1-They know they will crossing the ITCZ
2-They know (airmanship) that they can't climb safely
3-Captain Dubois is not in the flight deck

Titanic:
1-They will put lookouts for ice
2-They will increase speed !
3-They will not fully understand what happen (the severity of damages) and a officer will give orders for open hull gangway doors for embark passengers in the half-loaded lifeboats

AF447:
1-They will set their weather radar for better detection of dangerous areas
2-They will climb !
3-they will not fully understand what happen and take bad decisions

Epilogue:
Wrecks will be discovered after long and difficult research
Their discovery will help to understand more or less what happened but there are still shadows
The tragedy of the Titanic had results that some laws concerning maritime safety, construction and conduct of vessels have been modified
It is certainly true with regard to the world of aviation

Roger Greendeck 5th Oct 2012 01:22

Stall recovery training is a very interesting field of unintended consequences. We all learn stall recovery during basic training in docile aircraft relatively close to the ground. We are taught 'minimum height loss' which when practiced numerous times over a short period becomes in many pilots' minds 'no height loss'. To a degree this makes sense for the close to th ground case where there is not a lot of room underneath to recover.

But most of us end up in aircraft that fly well above the ground and hence we can safely trade height for speed. But even when we do stall training in a type rating course iris not enough to overwrite the earlier learning.

So much for the problem, what about a solution? Why not include stall recovery in basic training where the student cannot use power? ie they must lower the nose and trade height to speed. This caters for cases such as severe icing when full power has already been applied and for the future high altitude case where full power and nose up is not appropriate.

BEagle 5th Oct 2012 07:10


Lose no altitude, maintain back pressure. Thrust increase.
That nonsense has now been canned - it was some FAA Examiners' idiocy which was totally wrong. Both Airbus and Boeing have now had to rewrite their stall recovery procedures to ensure that the emphasis is on reducing AoA. 'Unload for control' was once a well-known maxim; sadly that seems to have been forgotten by many.

Control may be compromised if TOGA is applied as this can generate a powerful pitch/thrust couple which can exceed elevator authority if the aircraft has auto-trimmed to the point of the stall.

Pilots are also having to be reminded that 'minimum loss of height' may be undesirable as there may be occasions when the stall occurred because the aircraft was at excessive altitude for its weight.

A positive manner, disciplined flight deck procedures, sound training and attentive monitoring are needed - none of which were evident in the AF447 accident.


Why not include stall recovery in basic training where the student cannot use power?
In the UK, this is taught during a student's very first stalling lesson. Only when the technique has been mastered are students introduced to the additional technique of minimising height loss by use of power.

Notwithstanding an entirely adequate 'Unreliable air speed' QRH procedure, I do think that all large aircraft should be fitted with independent AoA gauges.

BOAC 5th Oct 2012 14:03

Apologies if I have missed this in the welter of OOZLUM bird flocking, but do we know if AB have now addressed the logic for the stall warning 'inhibit' below 60kts?

DOVES 5th Oct 2012 16:58

NOOO!!!
(I don't know how to say it louder).
Please tell me that's not true, no one has ever said such a folly:

Quote:
Lose no altitude, maintain back pressure. Thrust increase. That nonsense has now been canned - it was some FAA Examiners' idiocy which was totally wrong. Both Airbus and Boeing have now had to rewrite their stall recovery procedures to ensure that the emphasis is on reducing AoA. 'Unload for control' was once a well-known maxim; sadly that seems to have been forgotten by many.

Control may be compromised if TOGA is applied as this can generate a powerful pitch/thrust couple which can exceed elevator authority if the aircraft has auto-trimmed to the point of the stall.
...and the tail tank is full, adding a stronger pitch up moment!
I think I have to stop teaching old stuff to my students and burn out all my manuals!

Lonewolf_50 5th Oct 2012 19:29

Roger, the stall training and stall recovery training that I taught as a flight instructor did not have "minimum altitude loss" as a criterion, but there was a time when the approach turn stall training did have some attempts to "quantify" what number of feet lost was a criterion for success. I typically argued that if you teach good technique and good procedures, you will recover with minimum practical altitude loss. (Uh, and I was right about that).

I won't bore you with the various battles I fought over that, but do agree with you that stall training at altitude has numerous benefits, particularly when you teach it as a power independent training maneuver.

Clandestino 7th Oct 2012 20:07


Originally Posted by fustall
This was the start of the problem,how did Airbus get away with fitting inferior pitot tubes with inferior heating elements?

Conditions that lead to pitots being overwhelmed could not be replicated in any test and, besides 1) are very rare 2) are of short duration 3) were successfully negotiated every time except once.


Originally Posted by Lonewolf 50
they made the assumption that stall warnings that they were receiving were spurious.

Could be, but then it is pretty widespread standard in airline cockpits to react to false warnings with "DISREGARD (reason) " and tell the significant cockpit other what you think is going on and what you are doing. I'd be surprised if AF didn't have similar procedure.


Originally Posted by Lonewolf50
I am not convinced that a 5 degree nose up pitch held ad infinitum would do other than slowly fly them into a stall, or slowly fly them to their service ceiling.

With idle power they would have stalled, with climb power they would have leveled off below service ceiling, at altitude where power required for 5° AoA steady flight meets power available delivered in CLB detent. Come on folks! Basic aerodynamics is not that difficult.


Originally Posted by jcjeant
why Airbus (in the first place) fitted those particular brand and patent (Thales) Pitot tubes ?

1.18.1.7.


Originally Posted by Lyman
I disagree, utterly. you would enlarge your understanding manifold once hearing evidence that is unfortunately unavailable to you, or to the public.

The CVR tells BEA everything, they tell us next to nothing. It is quite possible the CVR will find its way into the public domain. If available to you, would you listen? Or would you cover you ears, satisfied with a 'story'...

So you have access to CVR recording that is contrary to one published by BEA but you just can't share it with us or it is pure conjecture on your part that CVR transcript is inaccurate or worse?


Originally Posted by truckflyer
Furthermore to Airbus pilots, when did Unreliable Airspeed become a memory item?

Before first Airbus took to the skies. First item is KEEP ON FLYING on every aeroplane.


Originally Posted by truckflyer
should they have been aware of these procedures.

Should they have been aware of the emergency procedure on their aeroplane? Maybe we should ask pilots if that's what is expected of them.

Originally Posted by truckflyer
From what the TV program showed, however much is correct there I don't know, but it does seem like the PF (RHS) locked/jammed the controls for to long time!

Name of this thread is "AF447 report out". Stick traces are available in the said report.


Originally Posted by Lonewolf 50
Typically, airlines do not do actual stall training in the aircraft (valid risk and cost reasons),

Exactly. On my current type full stall would cost an aeroplane and lives of the crew. That's why we are never trained to recover form it but rather to prevent it.


Originally Posted by lonewolf50
That sort of training is apparently not done.

...yet some managed not to crash their 330/340s even without the training.

Originally Posted by Lyman
Lose no altitude

That's very interesting way to describe 7000 fpm zoom climb near the ceiling.


Originally Posted by Retired f4
Or you are talking about an aircraft, where autotrim is keeping the aircraft trimmed into the stall?

Autotrim works both way but stick has to be held forward long enough that elevator alone cannot meet the G demand.


Originally Posted by BEagle
That nonsense has now been canned - it was some FAA Examiners' idiocy which was totally wrong. Both Airbus and Boeing have now had to rewrite their stall recovery procedures to ensure that the emphasis is on reducing AoA. 'Unload for control' was once a well-known maxim; sadly that seems to have been forgotten by many.

It is not nonsense.

It hasn't been canned.

It's just folks around still can't tell the difference between approach to stall recovery and stall recovery. Unsurprising if one can't tell the difference between the stall warning and stall.

Originally Posted by BEagle
Control may be compromised if TOGA is applied as this can generate a powerful pitch/thrust couple which can exceed elevator authority if the aircraft has auto-trimmed to the point of the stall.

So what. If autopilot autotrimed, manual trim is available. If FBW autotrimed, stick forward causes trim to roll in the opposite direction.

BEagle 7th Oct 2012 20:28


It is not nonsense.

It hasn't been canned.

It's just folks around still can't tell the difference between approach to stall recovery and stall recovery. Unsurprising if one can't tell the difference between the stall warning and stall.
It was nonsense and both Airbus and Boeing have now canned it. The revised teaching is also that recovery for an incipient stall and recovery from the developed stall require the same initial actions. Suggest you read your revised QRH.....


So what. If autopilot autotrimed, manual trim is available. If FBW autotrimed, stick forward causes trim to roll in the opposite direction.
I said elevator authority, not pitch authority. Due to the resulting very powerful pitch/power couple, TOGA from very low speed may cause excessive pitch angles to be achieved which elevator alone may be insufficient to prevent. This may cause excessive AoA to develop before use of the pitch trim can prevent this situation being reached.

jcjeant 7th Oct 2012 20:33

Hi,
clandestino

...yet some managed not to crash their 330/340s even without the training.
Yet some managed to stay alive after jumping of a plane even with no parachute or with a parachute malfunctioning :ok: (you will say it's rare ..... )
Anyways I will not take the chance to jump without parachute :=

FullWings 7th Oct 2012 20:49


So much for the problem, what about a solution? Why not include stall recovery in basic training where the student cannot use power? ie they must lower the nose and trade height to speed.
The aircraft I first learnt to fly on had no engine, so that was what you had to do!

My honest opinion is that we are seeing the results (in a wide sense) of the continuing spread of high levels of automation, including FBW and envelope protection. Statistically, flying is becoming safer but when accidents do occur, they trend towards the "what's it doing now?!" and/or failure to intervene when the automation has become unreliable.

I don't see much in the immediate future that's going to change this. Airline pilots who fly "conventional" airframes or light aircraft outside work get much more exposure to AoA, airframe performance and feedback; those whose only real handling experience outside of initial training is five or ten minutes in the sim every six months cannot be expected to have the same level of awareness or respond quickly in the appropriate manner when the computers give up and dump the whole thing in their laps. This is not a criticism of those pilots - we haven't yet got to a Matrix-style "I know Kung-Fu" as applied to aeroplanes, so there is little or no learnt/reflex behaviour to draw on in a problem situation. You can read the manuals as often as you like but nothing prepares you for the reality like continual practice.

The statisticians have probably worked out that overall it's better to have the odd AF447 when the automation can't cope than to rely on humans for the rest of the time...


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