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-   -   AF447 final crew conversation - Thread No. 1 (https://www.pprune.org/tech-log/466259-af447-final-crew-conversation-thread-no-1-a.html)

DozyWannabe 24th Oct 2011 13:35

@Capn' Bloggs : Again, somewhere on the Tech Log threads at least one Airbus FBW pilot stated that F/Os train on both sides of the flight deck, so left/right-hand orientation should not have been a problem.

Capn Bloggs 24th Oct 2011 14:39

Dozy, thanks. I missed that. We swapped seats on our Boeing course too. I just wonder how much practical time the bloke in the LHS had in that seat, given the predicament he rapidly found himself and his mate in. 4000-odd hours is not a lot when considering FL350 on autopilot 900hrs/year, hardly touching the stick and being in "wrong" seat, even given that they train in both. It would appear that the training they got wasn't all that flash.

Lomapaseo, in my book, skill is the most essential ingredient. You shouldn't need much knowledge to fly these things, either in or out of a stall. I do wonder about the wisdom of needing to remember to trim forward in this situation when you never do it at any other time (as far as I can make out, not being a bus driver).

Aeroplanes cannot recover themselves yet, but it seems managements the world over have let pilot's skills atrophy all the same.

lomapaseo 24th Oct 2011 15:51

Capn Bloggs


Lomapaseo, in my book, skill is the most essential ingredient. You shouldn't need much knowledge to fly these things, either in or out of a stall. I do wonder about the wisdom of needing to remember to trim forward in this situation when you never do it at any other time (as far as I can make out, not being a bus driver).

Aeroplanes cannot recover themselves yet, but it seems managements the world over have let pilot's skills atrophy all the same.
By identifying it as "skill based" shortfall, it sounds like it means that even though they knew that they were in a stall they did not know how to recover from it.

I suspect that ther may be some arguments against this.

and if it requires a "unique" knoweldge of the use of "trim forward" than that would be a " knowledge base " shortfall.

Capn Bloggs 24th Oct 2011 16:04

Lomapaseo, I see your point, but you didn't give us a "Situational Awareness" option, only a "skill" or "knowledge" option. ;)

By "skill" I mean the ability to observe the instruments, identify the situation, then decide what action to take and take it. :ok:

Lyman 24th Oct 2011 16:16

I would take it a step further.

Skill involves knowing when to ignore "Knowledge". It is unavailable to the format here, where rote and reference command at all times. Skill involves risk, and the ability to instantly observe, orient, decide, and act. If it is down to knowledge or memory alone, we are all screwed.

Knowledge PLUS Experience = Wisdom. And experience is not taught, it is acquired.

fireflybob 24th Oct 2011 16:25


Skill involves risk, and the ability to instantly observe, orient, decide, and act. If it is down to knowledge or memory alone, we are all screwed.
Lyman, thanks for that gem!

There is a difference between doing "things right" and doing "the right thing"

lomapaseo 24th Oct 2011 19:30

Capn Bloggs


By "skill" I mean the ability to observe the instruments, identify the situation, then decide what action to take and take it. http://images.ibsrv.net/ibsrv/res/sr...ies/thumbs.gif
Understood :ok:

Now that is basic use of all traits.

If it can't be demonstrated during training than a person should not be a pilot of anything. I doubt that the training sylabus needs reworking in that case but the pass/fail needs reviewing.

back to lurking looking for some new facts again :)

Clandestino 24th Oct 2011 21:40


Originally Posted by OK 465
We (he) know(s), I don't.

He knows that deep stall has specific meaning: the stall that cannot be exited by using aerodynamic means that are normally at aeroplane's disposal i.e. you need to deploy antispin chute to exit it. He knows that only practical mean to get into deep stall with airliner is to get the stabilizer and elevators in wings' wake when stalled. He knows that the only known way to achieve it is to include T-tail in aeroplane's design. He has seen some A330s and concluded that there are no T-tailed A330s. Therefore he knows A330 is not susceptible to deep stalls.

Do you now know that A330 is not susceptible to deep stalls or do you have issue or few with what I've written?

Argument that "No transport aeroplane has been flown so out of the envelope as AF447 so we don't know what is so far out and there might be deep stall area somewhere out there" is not particlarly meaningful or true and is similar to:


Originally Posted by Golgafrinchan captain, as quoted by Douglas Adams
To those who said that they had a feeling soap wasn't found in mines, the Captain had ventured to suggest that perhaps that was because no one had looked hard enough, and this possibility had been reluctantly acknowledged.


Originally Posted by Aileron Drag
This stall was induced by the pilot pulling the nose up into and beyond 'coffin corner'

Absolutely not. Coffin corner is altitude at which 1g stall line intersects Mach bufffet line. Only overpowered, low Mach no limited aeroplanes are capable of reaching it and A330 is neither. Coffin corner is not where Vls meets Mmo!


Originally Posted by Ross Detwiller, as quoted by Brian Abraham
The challenges the crew of Air France 447 must have been facing on the night of June 1, 2009, over the South Atlantic are known. Sensory systems appear to have iced up, negating their input. From what I’ve read, the airplane was held in a high angle of attack (AOA) position due to back stick pressure being exerted. With a frozen pitot static system, indicated altitude does not change and indicated airspeed increases with altitude. So they may have initially thought they were going fast and maintaining altitude. If true, that might explain why they continued raising the nose.

It is bloomingly clear that only pitots were frozen and measured altitude was correct all the time. Why-oh-why didn't he read and understand the report? His arguments are totally invalid.


Originally Posted by Ross Detwiller, as quoted by Brian Abraham
Did they remain in "controlled” flight all the to the water because the FBW wouldn’t let the airplane exceed the stall AOA?

No. Aeroplane was in alternate law. No protections. This was known two years ago as the message concerning FBW degradation was sent via ACARS.


Originally Posted by Ross Detwiller, as quoted by Brian Abraham
Did FBW add to the confusion by making inputs of its own?

No. Report 3 is pretty clear on that. It just followed pilots' demand, as programmed to do under the circumstances.


Originally Posted by Ross Detwiller, as quoted by Brian Abraham
I’m not saying that’s what happened because I don’t know and no one else has pointed to that fact

Very well, because that's not what happened and BEA did point that but then you have to understand what was written. Not an easy task for prejudiced, ignorant or both.


Originally Posted by RenegadeMan
but if the side stick of an Airbus behaves (sometimes, always or only occasionally such as perhaps when the aircraft is fully stalled) in a manner not dissimilar or even a little bit like the old video game I’ve mentioned above (i.e. the pilot makes an input such as ‘stick fully back’ and a substantial forward stick counteracting input is required to negate the state that the first input leaves the aircraft in)

It does not. Not in any control law. Rest of your post is based on this assupmption and is therefore not true.

OK465 24th Oct 2011 22:06


Do you now know that A330 is not susceptible to deep stalls or do you have issue or few with what I've written?
No and yes in that order. :)

Lyman 24th Oct 2011 22:32

Look at the pretty picture of A330 earlier, note the AoA, the position of the tail feathers, and the extended disturbed airmass present about the aft fuselage.

I vote with OK465. Elevator authority is demonstrated how? Tunnel time.

All arguments post STALL have a fascination that is understandable, and useless and irrelevant at the same time, unless certification standards are altered. Especially the funny parts about the instrumentation being reliable.

Loose rivets 24th Oct 2011 22:56

OK465


LR. It was only a comment on AD's tidy summation.
It's odd, I guessed you'd popped in between AD's post and mine by a second or so. But time does go by fast at my age.

Time and time again I'd asked if the 330 could deep stall, as there have been sooooo many references to it having done so. What I didn't do was assert myself in the way AD did.

I still do not know if it is possible for the A330 to become LOCKED into a stall - given all of the controls are functioning. I have always assumed it could not, but I've been surprised before.

Is there ANY way it could be stable and unrecoverable given say, <60 kts airspeed and high vertical speed? Again, all controls - especially the tailplane - fully functional.

ChristiaanJ 24th Oct 2011 23:00

For the sake of using the same terminology, could we agree to the following ?

A "deep stall" (or "locked-in stall") is the classic term for what happens to T-tailed aircraft, when AoA is such, that the wing wake 'blanks' the horizontal stabilser and negates pitch control.
As stated before, about the only way out is a tail parachute.

A "full stall" (or "fully developed stall") is when you pull the aircraft (any aicraft, Cessna or 747 or A330)) beyond the stall AoA and hold it there, either by control input or by THS trim.
With the horizontal stabiliser below the wing wake, full ND elevator, and trimming the THS ND should allow recovery, even if not instantly.

AF447 was in a full stall, not in a deep stall, as most 'aerodynamic engineering oriented' people here understand it.

CJ

Loose rivets 24th Oct 2011 23:10

That's as I always understood it.

Looking back, it's strange how we glibly did all our training in BAC 1-11s right through to the push. We didn't have a sim for 5 years and Mike Lithgow and Capt Keys were still very fresh in our minds.

Aileron Drag 24th Oct 2011 23:13

Let's go back to basic aerodynamics. The definition of a 'deep stall' is that the stalled airflow from the main-plane is blanking off the horizontal stabilizer, thereby rendering it ineffective.

By definition, therefore, an aeroplane susceptible to a deep stall must have a T-tail. The Airbus is most certainly susceptible to a 'locked-in stall' (that is, locked-in by the pilot holding the control column hard back), but cannot by any stretch of the imagination be susceptible to a deep stall.

There is some confusion on this thread about the literal meaning of 'deep stall'.

I suggest that, because of the very 'conventional' design of the Airbus, with the wing and horizontal stab pretty much in line (just like a DC3), it is not possible to deep-stall any mark of Airbus.

ChristiaanJ 24th Oct 2011 23:19


Originally Posted by Aileron Drag (Post 6768660)
There is some confusion on this thread about the literal meaning of 'deep stall'.

My point entirely.
I was just hoping to clear up the confusion, and avoid unnecessary posts on the subject.
There's enough confusion on other issues.... :ugh:

OK465 24th Oct 2011 23:21


He knows that the only known way to achieve it is to include T-tail in aeroplane's design.

By definition, therefore, an aeroplane susceptible to a deep stall must have a T-tail.
The canard configured Velocity had a deep stall problem initially.

No T-tail.

Aero changes were made so they didn't fall on you.

DC-ATE 24th Oct 2011 23:40

OK.....here I am.....again. Why can't we all just admit that if this had been a "conventional" airplane [cable-operated, not computer/electric-operated] that we would not even have a thread on this?! Let's just wait for the final outcome on the investigation to see just what "they" have to say about all this.

I have been [flying at the time] in a "full-stalled" jet transport [cable-operated] before.....AND recovered.....so I know it's possible.

Lord Spandex Masher 25th Oct 2011 00:05

AD, just curious. How far above the main wing is the 330 elevator? Is it a similar distance as, for example, a BAc 111?

You simply can't confine deep stalls or super stalls to T-Tail only types. It is entirely possible to get a deep/super stall on a conventional (read not a T-Tail) type. A swept wing is actually more prone to a deep stall than a T-Tail but a T-Tail is harder to recover, hence pushers and all that jazz. Remember swept wing pitch up?!

I haven't read the entire million threads but does anybody know where the CofG was?

Lyman 25th Oct 2011 00:07

DC-ATE. Disagree. For the simple reason there is no data to rely upon, and intuitively, the difference in fbw, cables has naught to do with this STALL.

Just as the discussion is not only O/T, it is off Planet.

It isn't necessary to display good behaviour whilst STALLED to get the cert.

For ducks, my opinion is that the ship would begin a recovery as the elevators went nose down, but as drag decreased on the tail plane, it would regain its nose up designed in behaviours due better aerodynamics/drag, and the airframe would be unrecoverable. UNTIL THE THS MIGRATED BACK TOWARD NEUTRAL< AT WHICH TIME THE NOSE COULD DROP< AND RELOAD THE WINGS>

Without trim, the a/c would have recovered itself, even with full up elevators. Eventually, nose down elevators would be needed, or its porpoise into the sea, imo. Also less thrust would be nice. My guess is at first drop, the pilot would grok his space.

M'Lud: The cofg was initially reported by BEA as 37. They changed that to 28, later, without explanation. And generally without comment here.

Mustn't discuss.

Wait, could the 5000fpm VSsel have been the a/p response to command from FCM to load the tail due AFTCG? hmmmmm....

After a time w/o the cg adjust, did a/p drop as a result? Could that have been the chronic nose down the PF was hobbled with? Musical cg's?

stepwilk 25th Oct 2011 00:32


that the wing wake 'blanks' the vertical stabilser
Horizontal stabilizer.


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