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American 767
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Air Asia QZ8501 SUB To SIN Crash - Part 12

Mon Jan 19, 2015 11:53 pm

Please continue the discussion here.

Air Asia QZ8501 SUB To SIN Crash - Part 11 (by American 767 Jan 15 2015 in Civil Aviation)

May all the victims rest in peace.

Ben Soriano
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Kaiarahi
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:04 am

From Part 11:

SimonDanger
Has the airline you work for trained you, in actual aircraft or hours of sim-time, how to get into and out of a high altitude stall? Has that training focused on the effects of pitot tube freezing and it's downstream effects.


You do realize that Pihero is a training captain with about 40 years experience - right? I don't think reading this thread is equivalent knowledge or experience.
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:56 am

Quoting Pihero (Reply 1):
You could say the same things on 95% of the cruise accidents

So what ?
An anti A agenda ?

Or are you really interested, as an aviation fanatic, in knowing the truth and ways of promoting further air safety ?

I notice that my questions to you are un -answered.
Not convenient to your agenda, perhaps ?

"You could say the same things on 95% of the cruise accidents. So what ?"
-- Maybe, maybe not. I did not research every crash that occurred during cruise flight. Im just speaking of information that we have at this moment and yes I am comparing to AF447.

"An anti A agenda ?"
--- Nope, only you mentioned Anti A agenda. If 5 Toyota vehicles all crashed because stuck throttles are you going to get mad because I said the word Toyota? You're damn right it has to do with the manufacturer. I don't care about Boeing or Airbus nor do I care which was involved here. This A vs B stuff, It has nothing to do with my point. If AF447 was a 777, and Air Asia was a 737, guess what, I would have said BOTH are Boeings.

"Or are you really interested, as an aviation fanatic, in knowing the truth and ways of promoting further air safety ?" -- Yes I am absolutely interested to find out what happened. Who here isn't?

"I notice that my questions to you are un -answered.
Not convenient to your agenda, perhaps ?"
--- Give me some time man, I took my daughter to school earlier, picked her up, went grocery shopping with my wife, washed my wifes car, had dinner with my family, and now im sitting down looking at Airliners.net. No it was convenient to my agenda.


I had no intentions of making this A vs B only other people here seem to turn it into that.

[Edited 2015-01-19 17:07:01]
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:02 am

There is no way to prove, one way or another, what knowledge and experience anyone has. This is an anonymous internet discussion forum after all, where yours, mine, and mickey mouse's opinions carry equal weight. It's already bad enough that there is a percieved imbalance caused by one's RR rating, flag of origin, or post count ... the last thing we need is yet anohter label upon which we should, or should not, apply a measure of truthfulness to.

Gee whiz anyway ...

You see what happens when we try something like that? The above post, for instance, which comes off as a "how dare one challenge the great and powerful Oz, who by virtue of his very existence means he is incapable od error". This is NOT a good thing, and I'm sure he doesn't like it either. Too much responsibiliy, when he comes here for fun mainly.

We all appreciate the time and effort expended here by those who are fortunate enough to do as a job what all of us fantasized about while growing up. But lets not put human beings on a pedestal ... two such human beings met their end last month with their hands on the same sidestick as Pihero holds, and I'm sure they had similar praises to sing about their front office. Everyone is capable of error, and even those who've never been in an Airbus cockpit can still not only understand whats happening up there, but can also sometimes come up with something those who've dedicated their lives to this FCS might have missed.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:32 am

Most crashes these days are CFIT, be they at take-off, landing, or in cruise. I don't think the brand of airplane has proved a significant factor in most.

AF447 happened to an Airbus, but pilots losing instruments and the autopilot at cruise happened to all brands, the main difference being the reaction of the pilots. Had the pilots done nothing AF447 would probably have been fine.
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:52 am

Apparently the contents of the Cockpit Voice Recorder are 'recoverable' and will be at least partially published quite soon.

The investigators apparently think that hijack/sabotage/explosions can be pretty well ruled out.

http://www.abc.net.au/news/2015-01-2...terrorism-in-airasia-crash/6026592
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:00 am

Quoting md80fanatic (Reply 3):
There is no way to prove, one way or another, what knowledge and experience anyone has. This is an anonymous internet discussion forum after all, where yours, mine, and mickey mouse's opinions carry equal weight.

Not really. This is something usually quoted by uninformed people to add weight to their point of view.

Quoting md80fanatic (Reply 3):
The above post, for instance, which comes off as a "how dare one challenge the great and powerful Oz, who by virtue of his very existence means he is incapable od error".

Not really. No one is put on a pedestal. One of the things I really liked about a.net, back when it was less like a CNN comments section, was that I could interact with and ask questions of people that I normally do not have access to. Airline pilots, mechanics, military pilots, load masters, etc. I'm not really that interested in hearing what uninformed Joe Public has to say. If I was, I would stick to CNN and USA Today. And, yes, it makes sense to defer to experience. If you had 30-40 years in a profession and found yourself in a continual argument with people who knew almost nothing, you'd probably want a little respect/deference too.

Quoting md80fanatic (Reply 3):
We all appreciate the time and effort expended here by those who are fortunate enough to do as a job what all of us fantasized about while growing up.

Then let's listen more and argue less.

Quoting md80fanatic (Reply 3):
Everyone is capable of error, and even those who've never been in an Airbus cockpit can still not only understand whats happening up there, but can also sometimes come up with something those who've dedicated their lives to this FCS might have missed.

If, as a passenger, you found yourself on an AC that was in a high altitude stall, would you really want the pilot to ask for help/opinions from the cabin?
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:40 am

Quoting LovesCoffee (Reply 6):
Quoting md80fanatic (Reply 3):
The above post, for instance, which comes off as a "how dare one challenge the great and powerful Oz, who by virtue of his very existence means he is incapable od error".

Not really. No one is put on a pedestal. One of the things I really liked about a.net, back when it was less like a CNN comments section, was that I could interact with and ask questions of people that I normally do not have access to. Airline pilots, mechanics, military pilots, load masters, etc.
Quoting LovesCoffee (Reply 6):
If you had 30-40 years in a profession and found yourself in a continual argument with people who knew almost nothing, you'd probably want a little respect/deference to

  

Quoting LovesCoffee (Reply 6):
Quoting md80fanatic (Reply 3):
We all appreciate the time and effort expended here by those who are fortunate enough to do as a job what all of us fantasized about while growing up.

Then let's listen more and argue less.

I used to drive C130s, many years ago. I've nevertheless learned enormously on these threads from Pihero, Mandala499, Zeke, and many others. I am curious and sceptical - which means I ask my proctologist and oncologist questions and listen carefully to the answers. I don't pretend to have answers to questions that have been explored / experienced in depth by people who have years of expertise.

On the other hand, as an informed professional, I react vociferously to people who pontificate on things they know fornicatingly nothing about - such as the provisions of the International Convention on Civil Aviation - and even more vociferously to people who could inform themselves, but are too lazy to do so. Such as those whose knowledge of AF447 is based solely on media accounts. Before proving your profound ignorance, you should at least read the official report - and if you don't understand the DFDR plots (which are more important than the CVR), ask intelligent questions instead of pontificating about the state of civil aviation.

How many people on here are capable of understanding the DFDR plots of QZ8501? If you're not, ask questions. The professionals will, in my experience, be happy to respond. Same as my oncologist. It would never occur to me to contradict her 40 years' of experience, although I might seek another opinion from an expert in the field - but not from an amateur who's learned "everything" s/he thinks s/he knows from Wiki and Google.
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 3:38 am

Quoting trnswrld (Reply 2):

If 5 Toyota vehicles all crashed because stuck throttles


But you don't know that five Toyota vehicles crashed because of stuck throttles. You only know of one Toyota vehicle that crashed due to a stuck throttle. The others you wrongly assume have crashed because of the same problem. But at this point in time you can't tell if they did or didn't.

By the way, many of those stuck pedal accidents were actually attributed to senior citizens stepping onto the wrong pedal. Of course the media made it look like there was a huge problem with Toyota cars. And you obviously bought it. There was only one stuck pedal on a loner car from a dealership that piled a Lexus mat ontop of two existing mats in that Prius. Because one mat isn't enough, right ??
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 3:48 am

Quoting nav30 (Reply 5):
The investigators apparently think that hijack/sabotage/explosions can be pretty well ruled out.

All I have heard on the news today is that 'terrorism' has pretty much been ruled out by the investigators.

[Edited 2015-01-19 19:52:35]
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 4:13 am

I can't remember as fundamentally ill-tempered a thread as this twelve-parter in maybe 10 years of reading. Can we all try to listen, share, discuss and learn?
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 4:16 am

Quoting CO953 (Reply 11):
I can't remember as fundamentally ill-tempered a thread as this twelve-parter in maybe 10 years of reading.

The MH370 thread?  
Quoting CO953 (Reply 11):
Can we all try to listen, share, discuss and learn?

  
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 4:28 am

Quoting LovesCoffee (Reply 7):

What does this have to do with anything?

Because apparently I didn't respond quick enough so Piheros liking, so I made the point that I'm not glued to a.net all day.

Quoting ComeAndGo (Reply 9):

Quoting trnswrld (Reply 2):

If 5 Toyota vehicles all crashed because stuck throttles


But you don't know that five Toyota vehicles crashed because of stuck throttles. You only know of one Toyota vehicle that crashed due to a stuck throttle. The others you wrongly assume have crashed because of the same problem. But at this point in time you can't tell if they did or didn't.

By the way, many of those stuck pedal accidents were actually attributed to senior citizens stepping onto the wrong pedal. Of course the media made it look like there was a huge problem with Toyota cars. And you obviously bought it. There was only one stuck pedal on a loner car from a dealership that piled a Lexus mat ontop of two existing mats in that Prius. Because one mat isn't enough, right ??

Thanks for the info. I was more or less just using that as an example, but you are right I must have bought into the media. I only knew what I heard on the TV regarding that Toyota situation and never pursued it beyond that. I do recall all sorts of BS stories of people claiming to be stuck at full throttle then trying to sue. Typical I suppose and all fueled by the media.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 4:41 am

"Analysis of the flight data recorder would take longer because investigators were examining all 72 previous flights flown by the aircraft."

Sourced from: http://www.abc.net.au/news/2015-01-2...terrorism-in-airasia-crash/6026592

I suppose it's probably standard practice to do so; but it makes me wonder if they are specifically looking for some kind of specific anomaly in the aircraft's performance which may have occurred prior to the final flight.

"The final minutes of the AirAsia flight were full of "sounds of machines and sounds of warnings" that must be filtered out to get a complete transcript of what was said in the cockpit"

(Same source)

Sounds like things were desperate in their final moments, the pilots trying to work the problem until the last moment. The article seems to imply that the aircraft was more or less intact (there was at least a minimum level of electrical power and no catastrophic failure of the structure) through the final moments as well. I'm not an expert, but a functional FDR and CVR as well as aural warnings from the avionics imply at least some electrical power.

I think the actual chain of events after the initial failure must have been catastrophic, even if the initial failure was not.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 5:06 am

Quoting 777Jet (Reply 12):

Quoting CO953 (Reply 11):
I can't remember as fundamentally ill-tempered a thread as this twelve-parter in maybe 10 years of reading.

The MH370 thread?

ummm what are the commonalities between these threads?
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 5:30 am

I hope I'm not complicit in flying this thread into a stall, but I have an ignorant question. That is, I have naught but my own ignorance to build the darn thing out of, so I'm stuck with it.

Back when we got reports of the FDR data on AF447, I remember something to the effect that after the stall started, the plane had gotten to a fairly high bank angle on at least one occasion*, and the crew were able to recover the roll angle to a wings-level attitude. I remember thinking it ironic; that if the bank angle had gone high enough, the plane would have likely gone nose-down, which would have recovered from the stall. Then, assuming the crew could recover from the resulting dive, they would have been about their merry way, minus some thousands of your favorite altitude units.

Now, looking back on it, I'm betting my assumptions work a lot better in a small airplane in a cheap simulator. I really have no idea. Since QZ8501 seems, potentially, to have had an upset in rougher air conditions than AF447, it leads me to wonder anew, what *would* really happen if: an A320 (or other modern airliner), at cruise in undesirable weather, gets into a stall, and then happens to roll up near enough to a 90 degree bank that lift (and even the essential retardation of descent) is lost? Am I wrong in assuming the nose would tend to drop? Would this event be unrecoverable, or be recoverable with grave risk, or be a fairly minor upset?

*I'm not going to make any assertion that my memory isn't faulty regarding the actual bank-angle circumstances of AF447. I wouldn't be able to cite sources; if it is that I am mistaken, I'm willing to be corrected, but if one would wish to call me ignorant over it, it would be like proclaiming the wetness of water or the blueness of the daytime sky in many places not called the UK. It's a given, and not news.

Thanks! I appreciate the time you people take here!
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 5:57 am

A small update: a fisherman found what appears to be the nose of the aircraft in the waters around Sembilan Island, 650km from the crash site and not too far from the area where three bodies were recently found. A picture can be found here.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:00 am

Quoting flightless (Reply 16):
. I remember thinking it ironic; that if the bank angle had gone high enough, the plane would have likely gone nose-down, which would have recovered from the stall.

Yes, but . . .
They didn't realize they were stalled. The flying pilot thought he was in overspeed. The captain thought the falling altimeter was erroneous and the first officer was in panic mode.
The investigators found A) the flight was lost in the first 1.15 minutes and B) the stalled plane was not recoverable.

From what I understand, a modern passenger plane with its central center of gravity and engines on the main wing is impossible to recover from a stall. Therefore, everything is done to avoid pilots stalling in the first place. It's totally possible that pilots in dire straits somehow mentally cut out the stall warning alarm. In the Colgan crash the pilot also thought he was in overspeed and the stall warning alarm was on and ignored.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:10 am

Quoting ComeAndGo (Reply 18):
From what I understand, a modern passenger plane with its central center of gravity and engines on the main wing is impossible to recover from a stall.

Where did you hear that? It's not true at all. Airliners in fact have to be certified for stall recovery. Here is one such test: http://youtu.be/rS1yD9fQhBQ?t=1m40s
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:14 am

Quoting rusti999 (Reply 17):
A small update: a fisherman found what appears to be the nose of the aircraft in the waters around Sembilan Island, 650km from the crash site and not too far from the area where three bodies were recently found. A picture can be found here.

Looks like just the radar antenna cover, aka radome. It's lightweight and would float well.

It looks undamaged.

[Edited 2015-01-19 22:19:28]
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:17 am

Quoting ComeAndGo (Reply 18):
From what I understand, a modern passenger plane with its central center of gravity and engines on the main wing is impossible to recover from a stall.

It would not be certified to carry passengers if that were the case.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:37 am

Quoting nm2582 (Reply 14):
"Analysis of the flight data recorder would take longer because investigators were examining all 72 previous flights flown by the aircraft."

Sourced from: http://www.abc.net.au/news/2015-01-2...terrorism-in-airasia-crash/6026592

I suppose it's probably standard practice to do so; but it makes me wonder if they are specifically looking for some kind of specific anomaly in the aircraft's performance which may have occurred prior to the final flight.

They are looking at the rudder to see if it's behaviour can be noted in previous flights.

Unfortunately, it seems that the NTSC isn't interested in recovering the CMC data (which would have recorded what the ECAM was saying, something the FDR doesn't do)... If they don't grab that CF card in the FDIMU in the avionics bay... some might end up questioning whether the minister has been pressuring NTSC or not...

Mandala499
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 6:41 am

Quoting flightless (Reply 16):
gets into a stall, and then happens to roll up near enough to a 90 degree bank that lift

Other people on here have much more knowledge than myself, but my understanding is that if the aircraft is stalled but the aircraft is banked more than a few degrees, it will probably enter a spin.

Quoting ComeAndGo (Reply 18):
From what I understand, a modern passenger plane with its central center of gravity and engines on the main wing is impossible to recover from a stall

Perhaps you are alluding to a "Deep stall"? This is more or less unrecoverable as the tailplane loses authority because the wing is blocking the airflow (at least I believe that is the cause, I could have something mistaken here)
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 7:36 am

Quoting rusti999 (Reply 17):
A small update: a fisherman found what appears to be the nose of the aircraft in the waters around Sembilan Island, 650km from the crash site and not too far from the area where three bodies were recently found. A picture can be found here.
Quoting LTC8K6 (Reply 20):
Looks like just the radar antenna cover, aka radome. It's lightweight and would float well.
It looks undamaged.

This puts to definitive rest the * nose dive * theory and the in-flight break up of the nose.

Quoting mandala499 (Reply 22):
They are looking at the rudder to see if it's behaviour can be noted in previous flights.

So they suspect a catastrophic rudder failure ?
Do you know whether the engines have been running all the time ?

Quoting mandala499 (Reply 22):
Unfortunately, it seems that the NTSC isn't interested in recovering the CMC data (which would have recorded what the ECAM was saying, something the FDR doesn't do)

That would be a shame, as it records many more data than the DFDR, and trends too.
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nm2582
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 8:07 am

Quoting rusti999 (Reply 17):
A small update: a fisherman found what appears to be the nose of the aircraft
Quoting LTC8K6 (Reply 20):
It looks undamaged.

Image of an A319 radome:

https://www.flickr.com/photos/a380spotter/5760769835/

Sure looks about right.

I'm surprised that it looks (almost) ready to mount on an aircraft.

[Edited 2015-01-20 00:08:11]

[Edited 2015-01-20 00:09:26]
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 8:27 am

Quoting rusti999 (Reply 17):
A small update: a fisherman found what appears to be the nose of the aircraft in the waters around Sembilan Island, 650km from the crash site and not too far from the area where three bodies were recently found.

Wasn't there previously confusion about that name? I believe it's nowhere near as far away as you're suggesting.
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namezero111111
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 9:51 am

Quoting benjjk (Reply 23):
my understanding is that if the aircraft is stalled but the aircraft is banked more than a few degrees, it will probably enter a spin.

Banking by itself will not make you enter a spin. It would be an "accelerated stall"; i.e. at a load factor > 1G, which makes the stall more abrupt and 'violent', but far from catastrophic or unrecoverable.

In order to spin, you'd have to have asymmetrical lift. I.e. slip/skip condition (induced by cross controlling, or crosswind gusts), asymmetric thrust (prop plane due to prop wash, P-factor on non-counterrotating props), split spoilers/slats/flaps condition, part of one wing broken off, or anything else you might envision that would result in asymmetrical list.
Noteworthy here is that countering the roll with aileron will deepen the stall on the low wing and worsen your situation. You'll have to correct with rudder.

[Edited 2015-01-20 01:53:11]
 
jollo
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 10:37 am

Quoting benjjk (Reply 23):
Perhaps you are alluding to a "Deep stall"? This is more or less unrecoverable as the tailplane loses authority because the wing is blocking the airflow

I have a *really* hard time beliving than in a modern conventional airliner (swept wings. no T-tail, no canards), throttling back the engines to idle, trimming full down and keeping he stick foward won't eventually drop the nose. Successful recovery depends on how much altitude youìve got to expend.

And if nothing goes, rudder input + asymmetric thrust will induce enough yaw to accelerate one wing and decelerate another -> roll (and the accelerated wing's aileron recovers some authority, so further roll-> eventually the nose drops. If your aircraft will remain in one piece recovering from the resulting spin + dive is another matter.

I'd rather not talk about "unrecoverable" stalls in the real world: even AF447 was never in a true "deep stall".

[Edited 2015-01-20 02:39:08]
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 10:46 am

Quoting jollo (Reply 28):

  
A spin, even fully developed, is a relatively low-G maneuver.
That said, spin recovery does not have to be demonstrated for multiengine or transport category aircraft.
 
s5daw
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 10:50 am

Quoting Aesma (Reply 4):
AF447 happened to an Airbus, but pilots losing instruments and the autopilot at cruise happened to all brands, the main difference being the reaction of the pilots.

Yes. However, it is likely that the captain would see immediately when entering the cockpit that PF is pulling on a stick, even after told not to.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 10:55 am

Quoting benjjk (Reply 23):
my understanding is that if the aircraft is stalled but the aircraft is banked more than a few degrees, it will probably enter a spin.

It really depends on what you think a stall is, to most lay people and the media, a stall can mean almost any in flight emergency involving the airframe or engines.

The traditional sense of a stall, where altitude is maintained an thrust is reduced, you may enter an incipient spin and a spin with the incorrect application of aileron and rudder, most large aircraft like a A320 however they use a combination of aileron, and spoilers to achieve roll control. A stalled aircraft does not stop producing lift, what happens is that lift passes a angle of attack where any further increase in angle of at attack, lift will reduce.

Where the application of roll could be beneficial is when we are not looking at a traditional stall, however where you are looking at gross mishandling, or significant external influence resulting in an upset, the application of roll can be beneficial to regain positive load and to recover the airframe.

Quoting jollo (Reply 28):
trimming

That is a key point when looking at horizontal stabilizer which also has a significant range of movement independent of the elevator.
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michi
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 11:01 am

Quoting benjjk (Reply 23):
Perhaps you are alluding to a "Deep stall"? This is more or less unrecoverable as the tailplane loses authority because the wing is blocking the airflow (at least I believe that is the cause, I could have something mistaken here)

Not mistaken, but you forgot to add, that a deep stall normally requires a T-Tail. Therefore plane like the A320 is not prone to deep stall.
 
s5daw
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 11:23 am

Quoting michi (Reply 32):
Not mistaken, but you forgot to add, that a deep stall normally requires a T-Tail. Therefore plane like the A320 is not prone to deep stall.

Would a situation where the air speed is reduced to the point where elevator has no authority left also count as deep stall?
 
comorin
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:19 pm

Until we hear from the NTSC, I'd like to add my 2 cents from FL300:

A modern jet, flying in predictable weather, commanded by a top gun pilot ( arguably as competent as anyone here?), flies into the drink. What rare combination of events affected this ship to the exclusion of others nearby?

Grateful for any thoughts.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:20 pm

Quoting s5daw (Reply 33):
Would a situation where the air speed is reduced to the point where elevator has no authority left also count as deep stall?

No, because a "deep stall" always refers to a situation where the wings mask the airstream from the elevators.




Probably you refer to the so-called tailplane stall. It most often occurs in icing conditions, as the ice buildup destroys the airstream, and the elevators have no authority anymore.


David
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s5daw
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:28 pm

I'm not sure your interpretation is correct. If that was true, then airplanes with canards could not deep stall, but they do: http://www.apollocanard.com/4_deep%20stall.htm

IMHO, a proper definition of deep stall is simply: With both wings stalled, the aircraft may lack enough control authority to recover.

T-tail just makes it easer to stall the elevator!
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:34 pm

Quoting mandala499 (Reply 22):
Unfortunately, it seems that the NTSC isn't interested in recovering the CMC data (which would have recorded what the ECAM was saying, something the FDR doesn't do)... If they don't grab that CF card in the FDIMU in the avionics bay... some might end up questioning whether the minister has been pressuring NTSC or not...

Wouldn't Airbus want that data? Could they recover it on their own?
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 12:41 pm

Quoting s5daw (Reply 36):
I'm not sure your interpretation is correct. If that was true, then airplanes with canards could not deep stall, but they do: http://www.apollocanard.com/4_deep%2...l.htm

Were we talking about canard-equipped planes?  


David
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Rivet42
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:12 pm

Quoting LTC8K6 (Reply 20):
Looks like just the radar antenna cover, aka radome. It's lightweight and would float well.
It looks undamaged.
Quoting Pihero (Reply 24):
This puts to definitive rest the * nose dive * theory and the in-flight break up of the nose.

Maybe - but technically all it actually rules out is nose-first-into-water.
We're assuming it really is 'the' nose-cone? No reason to doubt it, but also no reason to assume it is without specific confirmation.
Facts, dear boy, facts. Lets stick with 'facts'. Let's also not forget, at some point the vertical velocity was 'recorded' as -24000fpm; that's a lot of energy for a 70+ tonne aircraft, and judging by the debris it wasn't all present upon impact, so rate of descent must have been reduced significantly prior to 0 altitude... What do the facts tell us? At some point it was descending rapidly, but hit the water with a (likely) nose-up aspect and low enough downward velocity to result in 3(?) large pieces of fuselage... Still quite baffling, frankly.

Riv'
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s5daw
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:15 pm

Quoting flyingturtle (Reply 34):
No, because a "deep stall" always refers to a situation where the wings mask the airstream from the elevators.
Quoting flyingturtle (Reply 37):
Were we talking about canard-equipped planes?  

Your justification is clearly wrong, as you used "always", which is clearly not the case.

So what did you really mean? Deep stall is _always_ refers to a situation where the wings mask the airstream from the elevators _in the airplanes which have H stab at the back_.

That would mean delta wing CAN NOT deep stall, which according to various sources that is not the case: http://ieeexplore.ieee.org/xpl/login...2Fabs_all.jsp%3Farnumber%3D6096086

So that's wrong, too. All your statement could mean is:
Deep stall is _always_ refers to a situation where the wings mask the airstream from the elevators _in the airplanes which have t-tail_. Well, AF447 didn't have t-tail.

Hence, I believe your statement is wrong, and deep stall occurs also in other cases in conditions.

The only generic definition of deep stall is: A Deep Stall, sometimes referred to as a Super Stall, is a particularly dangerous form of stall that results in a substantial reduction or loss of elevator authority making normal stall recovery actions ineffective.

HOW elevator authority is lost is not important, and t-tail is just one common way.

ALso, I hope you are not a pilot.
 
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KarelXWB
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:40 pm

AirAsia flight QZ8501: Plane climbed at speed 'beyond normal' then stalled, minister says:

http://www.straitstimes.com/news/asi...d-speed-beyond-normal-then-stalled
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Pihero
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 1:48 pm

Quoting namezero111111 (Reply 29):
A spin, even fully developed, is a relatively low-G maneuver.

One has to define low-G. It depends on the rate of thurn and could be quite high.

Quoting Rivet42 (Reply 38):
We're assuming it really is 'the' nose-cone? No reason to doubt it, but also no reason to assume it is without specific confirmation.

Having lived for 10 years, 3 times a day, 20 days a month,11 months of the year checking those radomes on walk-arounds and having one or two opened and checked for bird or lightning damage, I'll eat my cap if that is not an A320 family nose radome... That's even better than *fact* to me.
It is for me easy to identify this radome because it is in a very good condition : no trace of heavy rain or hail damage, the nose tip almost undamaged, no sign of tear / breakage visible on this side. Some delamination, but very little of it... causes unknown.

Quoting Rivet42 (Reply 38):
it actually rules out is nose-first-into-water.

Nose dive or nose first into the water... semantics, now ?

Quoting Rivet42 (Reply 38):
Lets stick with 'facts'. Let's also not forget, at some point the vertical velocity was 'recorded' as -24000fpm; that's a lot of energy for a 70+ tonne aircraft, and judging by the debris it wasn't all present upon impact, so rate of descent must have been reduced significantly prior to 0 altitude...

You see ? facts could lead to a faulty reasoning :
You infer that the crew had regained a measure of control over the flight path... Maybe.
Or it could be an altogether different trajectory - a falling leaf-type in which when the wings are against the path, descent rate reduces, to increase again when the wings are parallel to the flight path ( i.e. aircraft descending side-wise )... and never have the nose pointing to the flight path.
Mandala499's post never said that the rate of descent was been reduced from 24 000 ft/min to... ? It specifically said :"at one time reachiung 24 000 ft/min..."

Quoting s5daw (Reply 35):
IMHO, a proper definition of deep stall is simply: With both wings stalled, the aircraft may lack enough control authority to recover.

That's as good a definition as any.
However
1/- the canard deep stall falls into another phenomenon : by design the front surface generates a positive - pitch-up lift -. It is therefore more prone to stalling, sometimes even before the wing. Yep ! Deep stall it is.
But, a canard surface stalling before the wing is good for safety : it generates a pitch-down moment, thus preventing a wing stall.

2/- On a pure delta wing, as the elevators are at the trailing edge of the wing, a stalled wing means generally a stalled - useless - elevator... Deep stall again... That's the reason modern fighters - Grippen / Rafale / Eurofighter - have an all flying canard surface.

[Edited 2015-01-20 05:59:10]
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michi
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:22 pm

Quoting s5daw (Reply 32):
Would a situation where the air speed is reduced to the point where elevator has no authority left also count as deep stall?

What kind of situation are you thinking of?

A situation, where the speed is insufficient for the elevator to have an authority to control the airplane is difficult to imagine. I guess, you would have bigger problems than a deep stall at this point.

However, you still should have positive stability of the airplane. Commercial airplanes should have a positive stability (like an arrow with feathers at the trailing end), as far as I know.

Military planes are a different story. They are even built with negative stability to enable better maneuverability. "Positive" stability is achieved with the help of flight control computers.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:34 pm

Quoting Rivet42 (Reply 38):
Maybe - but technically all it actually rules out is nose-first-into-water.

I suppose it rules out a high velocity, nose first impact. But then, the state of the wreckage and bodies of the passengers already did that.

Are you suggesting just that? Or any kind of nose first impact, including a ditching attempt?
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s5daw
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:48 pm

Quoting michi (Reply 42):
What kind of situation are you thinking of?

I don't know, it's hard to imagine.
Well, one example -albeit not the best- of deep stall could be National Airlines Flight 102. Of course it was due to the load shift, but if you watch the video, at the top of the climb speed is virtually 0, then aircraft rolls and before the crash it falls kindof flat down, with extreme AOA on both surfaces.

in AF447, we have a situation where:
At 2 h 10 min 05, the autopilot then the auto-thrust disconnected and the PF said “I have the controls”. The aeroplane began to roll to the right and the PF made a nose-up and left input. The stall warning triggered briefly twice in a row. The recorded parameters showed a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS)… He also made a nose-up input that increased the aeroplane’s pitch attitude up to 11° in ten seconds.

So here, the plane is virtually stopped mid air and pitched at 11 degrees. Now I'm no expert, but under this configuration, isn't it likely that both - wing and Hstab - are stalled?
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:50 pm

Quoting s5daw (Reply 39):
Well, AF447 didn't have t-tail.

AF447 was never deep stalled throughout its descent. The upset was no longer recoverable after a certain moment because of insufficient altitude.

Quoting s5daw (Reply 39):
The only generic definition of deep stall is: A Deep Stall, sometimes referred to as a Super Stall, is a particularly dangerous form of stall that results in a substantial reduction or loss of elevator authority making normal stall recovery actions ineffective.

Correct, but incomplete: a "deep stall" is also in a *stable* AoA Equilibrium region, meaning that any pitch *down* disturbance will be countered by a positive (nose *up*) piching moment that will tend to raise the nose back up to the equilibirum point.

You'll need considerable nose down control power to get the AoA out of the stable equilibrium region and down into an *unstable* region, where a pitch down disturbance accelerates (pitch down moment). If your elevator authority is unable to provide enough control power to get out of the stalled AoA equilibrium, you're in a "deep stall".

If on the other hand you have enough elevator authority (and enough altitude to trade), eventually the AoA will get back into another stable equilibirum region in the "normal" flight envelope (that's for positive stability aircrafts; relaxed stability is for fighter jocks and we can safely ignore it).
 
Rivet42
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 2:57 pm

Quoting Pihero (Reply 41):
Having lived for 10 years, 3 times a day, 20 days a month,11 months of the year checking those radomes on walk-arounds and having one or two opened and checked for bird or lightning damage, I'll eat my cap if that is not an A320 family nose radome... That's even better than *fact* to me.

I trust your judgement!  
(Sorry, I was making a slightly pedantic point about what has, and has not, actually been confirmed - no intent on casting doubts over your familiarity with said object.)

Quoting Pihero (Reply 41):
semantics, now ?

Yes, probably. I thought you meant 'nose-first' into water, rather than just 'nose-first' downwards. I agree with ruling out the first, but not necessarily the second...

Quoting Pihero (Reply 41):
Mandala499's post never said that the rate of descent was been reduced from 24 000 ft/min to... ? It specifically said :"at one time reaching 24 000 ft/min..."

No, it didn't, but I would have expected an impact with that vertical component to generate a lot more pieces of debris than it has, especially if it was almost 'flat'. It's my deduction that the impact was at a slower vertical speed - it's been much debated and agreed by some already that the horizontal velocity was likely very low too, and we 'know' from reports to the media that the pilot was wrestling with the controls to the last moment, and if there is one thing he would have been trying to do, I would guess (correct me if I'm wrong) it would have been to reduce downward velocity as he loses altitude...
Still, not enough data yet, so it's all supposition. Please don't despair of all of us who may not yet concur with your own analysis... Eventually we will all know the same things, and then, as long as we are able to get 4 from 2+2, we will all be in agreement.  

Riv'
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LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 3:21 pm

http://www.bbc.com/news/world-asia-30902237

He says some things that make sense, and then some things that make you question what he says...
But he appears to be relying on radar data and not recorder data.

'The AirAsia flight which crashed in the Java Sea with the loss of 162 lives had climbed too fast before stalling, Indonesia's transport minister said.

Ignasius Jonan told a parliamentary hearing in Jakarta that flight QZ8501 had ascended at a speed of 6,000ft (1,828m) per minute.

No passenger or fighter jet would attempt to climb so fast, he said."

'Faster than a fighter'
...
Citing radar data, Mr Jonan said: "The plane, during the last minutes, went up faster than normal speed... then it stalled."

"I think it is rare even for a fighter jet to be able to climb 6,000ft per minute," he told a House of Representatives commission.

"The average speed of a commercial aircraft is probably between 1,000 and 2,000ft per minute because the aircraft is not designed to soar so fast."
 
cat3appr50
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 3:45 pm

Thank you KarelXWB for your post #40, regarding posting what really matters here and which is key information regarding relevant, critical investigative information direct from the Indonesian Transport Minister. IMO that should be the focus instead of all of this constant back and forth tangential discussion and back and forth criticism of others by some posters regarding others technical "fitness" to post here, which is becoming nearly unbearable (while these constant critics literally know nothing about an individuals/members direct relevant degrees, formal education, long term professional experience, knowledge, etc. of engineering, meteorology, management, and direct aviation knowledge and experience, etc.).
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 12

Tue Jan 20, 2015 3:50 pm

Quoting LTC8K6 (Reply 47):
Ignasius Jonan told a parliamentary hearing in Jakarta that flight QZ8501 had ascended at a speed of 6,000ft (1,828m) per minute.

No passenger or fighter jet would attempt to climb so fast, he said.

So what would cause this - some massive updraft?

I don't see the pilots choosing to try this, and the FBW protections would surely stop them doing so, unless turned off.
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