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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 19th Jan 2015, 20:17
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Originally Posted by Bergerie1
May I ask two questions:-
1. Why are we discussing spins when no one knows whether the Air Asia aircraft ever got into a spin?
2. How many large commercial jet aircraft have ever got into a spin?
It seems to me that the discussion is taking a wrong turn.
1 The answer to #1 is that it appears to fit the impact conditions very well. See http://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore-109.html#post8830502 At this point, it is just a theory until confirmed or denied by the accident investigation.
2. If it has wings, it can depart into a spin. Ask yourself what would happen to your twin underwing engine jet if it pitched up for some inappropriate reason and then compressor stalled one engine at an inopportune time due to the high transient AOA.
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Old 19th Jan 2015, 20:20
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I know what will happen to at least 95% of posts on this thread when FDR readout is available.
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Old 19th Jan 2015, 20:42
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Originally Posted by AM
The Concorde prototypes had a crew escape hatch
I'm not sure what your point is, but all the Airbus prototypes I've been on have had crew escape hatches. They would be used in case something went very badly during any of the many stall tests that were done.
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Old 19th Jan 2015, 20:50
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Thcrozier, while this definition is not universal, this is the way I think of stalls:
Stall - When the airflow separates causing the wing to loose lift. Most stalls can be readily recovered with a simple nose-down command, although the details can be tricky since one wing will often stall first resulting a sudden roll.
Deep stall - extreme stall where the nose is not allowed to drop and most forward speed is lost - forward speed is similar to the descent speed (e.g. Air France A330). Deep stalls take a long time to recover from since there is initially little airflow over the tail to provide a nose down command.
Unrecoverable stall - stall where the spoiled flow from the stalled wing effectively blanks the tail, completely preventing the necessary nose down command to recover - quite common in 'T' tail aircraft.


OK465 - I don't know how the FAA pilot would have done that, but my suspicion is that he was trying something that he wasn't supposed to and/or hadn't been briefed (that's happened before, where I do have first hand knowledge, when the FAA pilot performed a maneuver he'd been specifically told not to perform - tends to result in rather strained relations between Boeing and the Feds - and would also be consistent with it being kept 'quiet').
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Old 19th Jan 2015, 21:12
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@Volume

Interesting that they look at all the previous flights, is there some pre-existing malfunction suspected? Do they need to calibrate some models?
Why would one think that the investigators would not analyse previous flight data? For the purpose of a full investigation this must be done... simple as that. They're not "expecting" anything per se...
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Old 19th Jan 2015, 22:21
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all this talk of stalls...

just remember for those of you who haven't heard of the many types of stall...if you can't get the nose down...

you might try rolling into a steep bank and this may cause the nose to come down eventually. this was taught many years ago when concepts like deep stall came out.


I would like to think that most planes certified will likely NOT get into the hairiest of stalls without some coaxing from either a very good test pilot or an odd sort of computer scenario.

I imagine , right now, that at least a dozen people in indonesia have a really good idea of what happened ...and what didn't happen...we might hear something in 10 days or so...just a guess
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Old 19th Jan 2015, 23:38
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@A0283

Having had the misfortune to have done some transcripts of fatal air accidents, I can assure you that it takes longer than you would think and is more draining than you would think - especially when you know the people involved. Add in chaotic ECAM and cavalry charges and alarms etc etc and I am surprised that they have done as much as they have.
All the time you are aware that someone will challenge your transcripts so you go over and over. Each alarm has to be identified, each sound identified. Not a pleasant task at all.
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Old 19th Jan 2015, 23:43
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in a number of these accidents we hear of the mayhem of alarms going off on the flight deck. no doubt making it even more difficult for pilots to try to think clearly. while audible alerts are obviously helpful if one goes off, they rapidly achieve the opposite of the desired effect in a full on crisis.

just thinking out loud, but does it makes sense at some point to have them shut off when they system senses the pilots are trying to respond? they obviously know they need to recover but being screamed at by hal non stop is not delivering any kind of useful infromation at that point.
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Old 20th Jan 2015, 00:11
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We have reason to believe that the stall alarm cutting in and out on AF447 may have led to it being disregarded as spurious (and may have induced the PF to pull back again when airspeeds became valid and the alarm restarted). Certainly there is much more work to be done in providing prioritising relevant information to pilots in an audio saturated environment. I am anticipating a near impossible workload in the QZ8501 cockpit.
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Old 20th Jan 2015, 00:22
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audio saturated environment
That's a new one
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Old 20th Jan 2015, 00:25
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A recent sim exercise had an alarm repeat every couple of minutes during a busy procedure which rightly required the crews to formally acknowledge and evaluate the damned alarm each time it triggered. You don't want to get into the habit of blithely waving off repeat alarms without at least assuring yourself that it isn't something new, or worse, something new dressed in the previously used alert.

Cognitive overload under stress is a huge problem which the designers address by adding more unthinking and contextually ignorant alarms. Kind of like fixing a language problem by shouting.
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Old 20th Jan 2015, 00:50
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Boeing and Airbus on Stall Testing

A March 2013 lecture by an test piloe and a flight test engineer from Boeing and Airbus on stall testing:

Royal Aeronautical Society | Event | Jet Transport Stalls

Royal Aeronautical Society | Podcast | Jet Transport Stalls

Video of the lecture, about an hour and 40 minutes long:

https://www.youtube.com/watch?v=HVt6LiDbLos

The individual speakers (times approximate):

Paul Bolds-Moorehead, Boeing flight test engineer, 0:00:00 to 0:02:30; 0:27:00 to 0:37:00; 1:31:00 to 1:37:00

Stephane Vaux, Airbus flight test engineer, 0:02:30 to 0:27:00; 0:37:00 to 0:49:00

Van Chaney, Boeing test pilot, 0:49:00 to 0:59:00

Terry Lutz, Airbus Test Pilot, 0:59:00 to 1:31:00

A similar set of briefing slides from 6 months later at a Society of Flight Test Engineers meeting:

http://sfte2013.com/files/78988645.pdf

A search engine turned up this description of the briefing, with a few web links that have since changed:

http://theairlinewebsite.com/topic/3...nsport-stalls/

The same Airbus and Boeing people published a journal paper later, but it's subscription only:

Royal Aeronautical Society | Aeronautical Journal | Stalling transport aircraft

Bootleg source:

http://www.sfte2013.com/files/75234188.pdf

Last edited by Vinnie Boombatz; 20th Jan 2015 at 01:16.
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Old 20th Jan 2015, 07:35
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Alarm

In modern Electrical Power stations, in case of serious problem for the security of the plant, the system sounds the alarm requiring immediate action from the operator. Afterwards, lesser urgent requests for action appears on the screen and so on...

It had been found that too much alarm sounding at the same time stress the operator which might not take the corrective actions as requested.
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Old 20th Jan 2015, 07:49
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@ZFT


'audio saturated environment'
That's a new one

Not at all really and a lot of people, males in particular, have problems assimilating several noise sources.
It is something which happens at puberty to about 30 percent of males.
For myself it made learning morse code (in the Grey Funnel Line) the devils own job; all I heard was a stream of noise.
The same may happen if several people are talking at the same time; perhaps in somewhere like a pub where music may also be playing.
I wonder if this surprisingly common condition has been sufficiently thought about.
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Old 20th Jan 2015, 08:21
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I am far from convinced that there are many "spurious protection triggers" or "dumb designer mistakes". No, I am not a pilot
Yes it is quite clear to see that! I have seen guys & girls cancel genuine warnings because they are so used to cancelling a nuisance warning at a particular phase of flight....

All the talk on this thread of stalling may or may not be related to the accident in question, we will soon find out, but let me give the non pilots some practical info.

Is it possible to get a stall warning and a high speed warning go off at once without it being spurious?
Yes! Coffins corner.
All it would take is an updraft, especially when in bad weather and in turbulance. Descending to a lower altitude with increased margins between low speed and high speed is the only thing that will save your neck.

Put yourself in this situation. In moderate / severe turbulence at high level naturally only a few knots from low speed stall due to the G. Static tubes /smart probes ice up due to super cooled water droplets, first indication is that you are over speeding. If either you or the automatics reduce the power you are in a whole world of trouble.
To save your neck, recognition of the situation must be instant which is most likely not a practical stance.

You realise within a few seconds 'oh we must have unreliable airspeed' you decide to fly a sensible attitude and power as per the book, but guess what? it's already too late as you've already stalled the wing due to the initial reduction of power and / or severe turbulence.
So you now need to initiate a stall recovery but by this stage you don't trust any of your instruments so continue to fly that sensible attitude and power which you have been trained to do. It's very likely the instruments will be telling you that you are flying straight and level due to frozen ports. You are actually stalled and descending at 7000 + ft/min and you or the plane can't make sense of all the conflicting information before your eyes and that unfortunately is game over.

A good crew will recover from the above situation but the best solution is avoidance. Avoid the weather ahead, don't attempt to climb over and if you must go through or if you hit nasty turbulence, descend to a lower altitude immediately where your margins are increased and you buy yourself time to recognise the problem and carry out the sensible actions before it's already too late.

This is why a human brain will always be required in a flight deck to analyse and pre empt future problems.
Pilotless airliners? No thanks
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Old 20th Jan 2015, 08:25
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Also worth a reminder that when humans become "maxed out" the brain "deletes" hearing.
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Old 20th Jan 2015, 08:30
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CVR transcription is a very difficult task. There are typically four channels: LHS, RHS, Intercom & Cockpit ambient. Within these channels are multiple inputs such as Com 1, Com 2, Nav., Ramp, Inter-phone, PA, warnings etc. The comm. and nav. channels are easy to decode. The difficult ones are voice, ambient noises and warnings. These will have to be cross-checked against each other, FDR data, software versions, aircraft manuals etc. to determine exactly what warning sounded when, who heard and it and what was said. Only when combined with SOPs, cultural norms, company standards etc. can a complete audio picture be given. So maybe the 50% refers to first hour. If the complete CVR transcript takes less than two months, that will be rapid progress.
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Old 20th Jan 2015, 08:39
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Not at all really and a lot of people, males in particular, have problems assimilating several noise sources.
It is something which happens at puberty to about 30 percent of males.
I find this quite intriguing. What is the source of this information?
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Old 20th Jan 2015, 09:02
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I cannot remember the condition being given a name by the doctor I was sent to.
He asked me a series of questions one of which was 'Before puberty did you need to hold your nose when you swam underwater or jumped into water'
My answer was no.
He then asked me if I needed to do so now and I answered yes which was correct.
That was only part of the examination but he did not seem to think it was that unusual a condition.

I do not believe the condition can be picked up by normal hearing tests.
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Old 20th Jan 2015, 09:31
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gcal: I think it's called "Sensorineural deafness".
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