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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 20th Jan 2015, 11:53
  #2221 (permalink)  
 
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@ Ian W On sound and sound processing - under stress

Ian W --

The name given is low levels of discrimination. The ability to make out a particular sound or voice in amongst other sounds, or even just the ability to understand speech. In the extreme people can hear a voice but not actually discriminate the sounds into meaningful words. This is common in the deaf/hard of hearing and audiologists will carry out speech discrimination tests. This is usually done by playing voices of different people at different sound levels with or without background noise. They may talk in snippets or single words so there is no contextual clue to what the word is, or give a sentence that provides some contextual clues to what is being said. The count the bleeps type hearing test is just for that hearing it does not identify people who cannot hear voices or sounds well against background noise. I am surprised that this is not tested for. The person suffering a loss of speech or sound discrimination may not be aware of it, but will find talking/listening in noisy surroundings difficult and tiring.

This is totally different to the 'attentional' or 'cognitive' tunneling effect, where under pressure humans will focus on one particular part of their environment and exclude all others. If that is the wrong thing then that will lead to problems in a cockpit environment. Sounds are one of the first stimuli to be filtered out, the last to be filtered out are haptics (touch and feeling) hence the reason for stick shakers.
Great post Ian W. It would not suprise me, based on the status by today, if these aspects will return in discussions following the investigation, and will even find their way into the final report.

When you go from relaxed to stressful situations, and end up at the most extreme stress levels on human beings - then you go through something that I call "roll back" (using my own words - I am sorry, but I do not know if there is a scientific label for the whole 'movement'). Which means that the brain's main processing moves from the frontal lobe, to the 'centre of the brain', and finally down to the 'brain stem'. One of the effects is for instance that you cannot lift as much weight in an extremely stressful environment as in a relaxed one. The reduction can be up to 50%. I do not know any numbers for the degradation of pull strength ( ref old fashioned sticks).

Last edited by A0283; 20th Jan 2015 at 12:07.
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Old 20th Jan 2015, 12:09
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Under severe stress according to my psychiatric contacts you 'regress' towards primitive fight or flight (escape) mode. Both are problematic in high technology situations, which are not quite our evolutionary scenarios. One sub mode of 'flight' is to go catatonic or 'play possum'. I know of one incident where an inexperienced F/O got overwhelmed going into LHR and went to sleep and could not be woken until after landing.
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Old 20th Jan 2015, 12:35
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On the topic of stress, there is an interesting Dutch investigation into military personnel. I believe though that the report might be of interest for anyone working in a high stress environment.

http://tinyurl.com/m9kwpga

Short summary of the above PDF: The "scientifical" words for what others call easy things like "roll-back" (I like that expression) is perceptual narrowing and indeed it messes up your perception. One of the first senses to be disregarded is hearing unless it is short, distinctive and preferrably in your mother tongue. Motor skills deteriorate because smaller muscles aren't provided with enough oxygen due to the fight-or-flight state that adrenaline dictates where it is most useful to have a good flow in your large muscles to be able to do either. Loss of near vision is also among the things that hampers your performance.

EDIT: Another one, more directly related to stress in aviation:

http://tinyurl.com/pflgb95

If the radome found belongs to the missing plane, it looks very clean and I see no visible hail marks or scorching as by lightning.

Last edited by MrSnuggles; 20th Jan 2015 at 13:09. Reason: Found another pdf. Edit again for summary.
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Old 20th Jan 2015, 12:42
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There is no hail damage on that radome. It's in remarkably good condition. In fact it does not even show the type of erosion you normally see when a aircraft is flown through extreme rain.
It doesn't look like it has hit the ocean at 100 knots either.
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Old 20th Jan 2015, 12:58
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At that distance it's looking like it has detached before the crash, but whether it's turbulence or mechanical/latching failure remains to be determined.
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Old 20th Jan 2015, 13:01
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Assuming the radome was attached to the aircraft when it hit the sea, the radome has drifted on average 24km per day (550/23).
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Old 20th Jan 2015, 13:11
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Yes it could have drifted that distance and also no radome was reported lost when they requested climb only minutes before the crash position. It's possible also that it was detached in the uncontrolled descent if spinning, for example, with lateral airloads.
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Old 20th Jan 2015, 13:12
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6000 fpm climb and subsequent stall reported BBC News - AirAsia flight QZ8501 'climbed too fast'

Indonesia's transport minister has said AirAsia flight QZ8501 climbed too fast just before it stalled, crashing into the sea with the loss of 162 lives. Ignasius Jonan told a parliamentary hearing in Jakarta the jet had climbed at a speed of 6,000 ft (1,828 m).
"It is unlikely a fighter jet would increase its flight level at a speed of 6,000 ft per minute," he said.
There were no survivors when the jet crashed in the Java sea on 28 December, en route from Surabaya to Singapore.
The Airbus A320-200 is thought to have encountered difficulties from an approaching storm.
Bodies are still being retrieved from the crash area where debris was scattered across the sea.
The cockpit voice recorder and flight data recorder were found last week.
The fuselage of the plane, believed to hold most of the bodies, has also been located and search teams are now working out how to retrieve it.
The authorities are expected to issue a preliminary report on the crash on 28 January.
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Old 20th Jan 2015, 13:24
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Nice attention grabbing headline, but how long was that rate of climb maintained for ?
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Old 20th Jan 2015, 13:28
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It's not a controlled rate of climb. 6000'/min is impossible at that altitude and type. It's a pitchup zoom climb possibly aided by updraft with reducing IAS into a stall; then we are guessing.
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Old 20th Jan 2015, 13:37
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6000 fpm

That report of the 6000 fpm climb is based on old radar data, not FDR data.
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Old 20th Jan 2015, 13:51
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It was the Indonesian transport minister not a journalist that claimed that it climbed "too fast", so the assumption is that the "old radar data" has been confirmed somewhat by data already gleaned from the recorders. It's also stated that it stalled which they would probably know by now. Also updrafts do not necessarily bleed airspeed but zoom (speed for height) climbs always do. The pitchup into a stall scenario during the climb to FL 340 now seems most likely for whatever reason.
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Old 20th Jan 2015, 13:58
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"Audio saturated Environment"

"Audio saturated environment" is a very appropriate expression for the cascade warning sounds bombarding the pilots during an abnormal occurance on a modern airliner. Add it to the lexicon!
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Old 20th Jan 2015, 14:21
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6000'/min is quite believable for an updraft. Even paragliders have been known to climb at 4000'/min in quite modest Cb.
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Old 20th Jan 2015, 14:28
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Of course 6000'/min is possible for an updraft, but gliders do not stall when they enter thermals. They gain total energy, The ROC mentioned is adequately explained by trading speed for height. There equally could have been a slight downdraft.
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Old 20th Jan 2015, 14:50
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Originally Posted by RifRaf3 View Post
Of course 6000'/min is possible for an updraft, but gliders do not stall when they enter thermals. They gain total energy, The ROC mentioned is adequately explained by trading speed for height. There equally could have been a slight downdraft.

6000 fpm unexpected in an Airbus with a change of Outside Air Temperature? Not at all impossible indeed its happened before.

For 18 seconds after the autopilot disengaged the aircraft remained within 200 feet altitude of FL
360 but once AoA law was invoked at 14:21:50 hrs, the aircraft's attitude began to pitch nose-up.
The pitch-up trend continued for 17 seconds reaching a peak of 15 nose-up shortly before the first
nose-down sidestick command was applied. Throughout this phase the aircraft climbed rapidly
(reaching a peak rate of about 6,000 ft/min) due to the increase in lift created by the flight control
system's capture of alpha prot.
The aircraft reached its apogee at FL 384 at 14:22:28 hrs where the
airspeed had decayed to 205 KIAS and 0.67 Mach even though full thrust had been applied.
Throughout the turbulence encounter, the normal g fluctuations were between 0.5g and 1.5g. The
recorded wind direction remained within 20 of the mean of 240 but the wind speed varied
between 67 kt and 108 kt and the static air temperature fluctuated between -42 C and -52C. There
were 7 cycles of temperature change, the second cycle being the most severe. The mean air
temperature before the AIRPROX event was -46.5 C and afterwards it was -44.5C. The crew
subsequently descended back to FL 360 and successfully re-engaged the autopilot and autothrust
systems.
http://www.rvs.uni-bielefeld.de/publ...pdf_501275.pdf
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Old 20th Jan 2015, 15:06
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Pick a number- pick a source

Geeze ...

AirAsia Jet Climbed at Rate Beyond Design of Commercial Planes
Plane Climbed at Rate of More Than 8,000 Feet a Minute, Transport Minister Says

The Airbus Group NV. A320 jet turned left away from its assigned flight path en route from Surabaya to Singapore, climbed at more than 8,000 feet a minute—six to eight times the normal rate—descended and finally disappeared within three minutes, Mr. Jonan said, citing data from the plane’s automatic dependent surveillance-broadcast, or ADS—B, system.


Note it is not from the FDR!

Pitot problems ??
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Old 20th Jan 2015, 15:08
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That's one credible scenario to account for the 2000' odd overshoot of assigned altitude and the eventual stall. You often get temp changes in CBs, however it could also be sensor icing and autopilot pitchup or pilot error. There's not enough data yet to factor out all the possibilities.
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Old 20th Jan 2015, 15:11
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Originally Posted by RifRaf3 View Post
That's one credible scenario to account for the 2000' odd overshoot of assigned altitude and the eventual stall. You often get temp changes in CBs, however it could also be sensor icing and autopilot pitchup or pilot error. There's not enough data yet to factor out all the possibilities.
Enter an updraft which by definition has higher temperature than the surroundings and is already carrying you up fast and then the aircraft does an 'assist' by climbing at 6000fpm inside the updraft. All IMC.
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Old 20th Jan 2015, 15:17
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It seems that we are back to square one if he's just quoting the ADS-B figures because all these variables like temps and extreme gusts may adversely affect the accuracy of the sensors supplying that ADS system.
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