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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 21st Jan 2015, 02:19
  #2281 (permalink)  
 
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rifraf3

you make some fine points. I think THEY hit an energy enhancing event (ie updraft etc). the plane reacted by trying to hold altitude, OVERSPED, then pulled up, trimmed up, THEN GAVE UP

and the pilots suddenly were in alternate 2 or direct law and forgot to manually trim nose down

stall, fall, bye bye you all.
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Old 21st Jan 2015, 03:47
  #2282 (permalink)  
 
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They really need to recover the horizontal stab jackscrew.

.
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Old 21st Jan 2015, 04:18
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Could the loss of Radom be the cause of sudden NU attitude ? We lost once a MD-82 (conic) tail cone at landing after a seemingly unverified and wrong exercise from cabin crews, and the Captain/PF was used to land very NU...?

Thank you Machinbird for the flat spin theory : waiting the FDR report unpatient :-)
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Old 21st Jan 2015, 04:30
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A damaged or missing radom obviously can cause a huge airflow disturbance aft of the nose, the pitots, alpha and beta vanes would be severely affected by this as well... I think the effect on the control surfaces would be a much smaller problem than the loss of reliable air data.
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Old 21st Jan 2015, 04:36
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28 January report not to be public
Minggu Depan, KNKT Selesaikan Investigasi Awal AirAsia QZ8501 - Kompas.com
http://www.reuters.com/article/2015/...0KU09X20150121
Happy ? as we can speculate more !

Last edited by jcjeant; 21st Jan 2015 at 04:49.
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Old 21st Jan 2015, 05:49
  #2286 (permalink)  
 
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That would be a first, not being released to the public. Maybe he means that there will not be a dumbed down report for the public, or he means that there will only be a minimal pro forma summary for ICAO as the investigation continues.

I am unaware of any civil accident investigation results not being in the public arena.

Either way, the statement is not a good look as it raises the ugly spectre of official interference in process.
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Old 21st Jan 2015, 07:22
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Maybe he means that there will not be a dumbed down report for the public, or he means that there will only be a minimal pro forma summary for ICAO as the investigation continues.
He does say that the full final report will be put on their web site, but the preliminary report may not be made public. I had a quick look at Annex 13 and it does include the people who must receive the report, but not who may not. He has previously said that this report will be only a very brief statement of the facts known, not any analysis. That was before they recovered the FDR/CVR though, so they may be tempted to include more information.
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Old 21st Jan 2015, 07:31
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Zorin

Great & worthwhile contribution on windshear/ momentum exchange and
energy exchange. Time these situations were programmed into
the AB autopilot in a somewhat more sensible fashion than 'just climb or
disconnect'


...unlike all this ridiculous media spew about... 'climbed too fast'

'We' perhaps know what was meant, but the general media and
public have definitely got the wrong end of the stick... time even
the BBC used a 'proper' aviation correspondent rather than some
'Technology Twit' who just regurgitates without thinking - annoyed
at this general dumbing down!
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Old 21st Jan 2015, 07:42
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... Just to add.

It'd almost certainly be speed and attitude
management after the rapid climb phase that
will be 'critical'...

Going 'over the falls' with rapid reductions in
net energy is where a stall is more likely to
originate than 'too fast a climb'.. duh!
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Old 21st Jan 2015, 08:14
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Interesting graphic based I suppose on radar data published by Ministry of Transportation. In Indonesian but its not very difficult to figure it out

kaki/menit - ft/min
detik - seconds
ketinggian - altitude

They turned left and 6 seconds after that started to steep climb - 1700 feet in 15 seconds. And further to 36.700 ft (3000 ft in 13 seconds?)


Jatuhnya AirAsia Versi Menteri Jonan

Last edited by klintE; 21st Jan 2015 at 08:32.
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Old 21st Jan 2015, 08:24
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Originally Posted by jcjeant

The families of those who perished will be have to be told, and once they are informed, we will know what they know within an hour.
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Old 21st Jan 2015, 10:15
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Zorin and HarryMann

Agree, very interesting. I did an energy management exercise and plugged in some numbers. They suggest that to bleed off the excess kinetic energy caused by a 50-knot airspeed increase due to the jetstream, the plane needs to climb approx 2000 feet. This corresponds well to the FL370-390 reported by Zorin.

But now if there is even a slight overshoot, speed will decay below the
original speed and at that altitude the stall margin is very small. And with a 6000 fpm climb rate the climb took just 20 seconds, so leveling off needs to be both quick and very precise.

One wonders if a safer strategy for bleeding off excess speed in that situation could be to use the speedbrakes and/or power setting?

Then in the case of QZ8501, that might not have been an intuitive action given that they actually wanted to climb above the weather. Maybe they found themselves in an unexpected but welcome climb, and then just did not realise how quickly they would have needed to level off in order to maintain flying speed.

The FDR data will surely be very interesting.

Last edited by snowfalcon2; 21st Jan 2015 at 10:21. Reason: typo
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Old 21st Jan 2015, 10:31
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AirAsia jet's alarms 'screaming' at crash

"Jakarta: Warning alarms in AirAsia flight QZ8501 were "screaming" as the pilots desperately tried to stabilise the plane just before it plunged into the Java Sea last month, a crash investigator says.

The noise of several alarms - including one that indicated the plane was stalling - can be heard going off in recordings from the black box in the Airbus A320-200's cockpit, the investigator told AFP, requesting anonymity.

..."
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Old 21st Jan 2015, 10:35
  #2294 (permalink)  
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Originally Posted by Australopithecus
That would be a first, not being released to the public.
He goes on to say the final report will be released to the public from their website.

This is where the report will be uploaded once released.

AAIC
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Old 21st Jan 2015, 10:40
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AirAsia QZ8501: Pilots' Voices were Drowned out by 'Screaming' Alarms Before Crash

Investigators have eliminated the probability of a 'terrorism' angle behind the crash, after they found no "suspicious noise or explosion" while analysing the voice recorders.
Perhaps also rules out radome coming off as initiator?
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Old 21st Jan 2015, 10:45
  #2296 (permalink)  
 
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@klintE - flight path by Indonesian MoT

Interesting graphic based I suppose on radar data published by Ministry of
Transportation. In Indonesian...
When I put the numbers in and try to translate the text I get this (all dots are 'spaces' to get the layout right):

.ft/min....ft......ds..ssec..dft...estfpm.....description
..1400..32000...6...6...xxxx....+1400......6 seconds after the maneuver to the left, QZ8501 suddenly pitched up/climbed
..6000..33700..15..21..1700...+6800.....15 seconds later, the aircraft had climbed 1700 feet from its original level
11100..36700..13..34..3000..+13846....13 seconds thereafter the aircraft reaches its maximum altitude
xxxxx..35200...6...40..1500...-15000......6 seconds thereafter It had dropped 1500 feet
xxxxx..27300...x....xx..7900...-xxxxx......? seconds, the aircraft continued to descend and dropped another 7900 feet
xxxxx..xxxxxx..x....xx..xxxxx..-xxxxx......? seconds, shortly after touching heights
xxxxx..xxxxxx..x....xx..xxxxx..-xxxxx......? seconds, and finally radar contact is lost

With ft/min = as indicated in the image, ft = as indicated flight level, ds = time step in seconds, ssec = sum of time steps which gives a timeline, dftestfpm = fpm based in numbers stated (they differ from the fpm stated, note also the 13k versus 11k and the 15k), description = indonesian text after my rough translation.

The climb of +13846 fpm is 1.98 times the value of pprune mentioned 'recoverable' incidents of 6000-7000 fpm.
..The drop of -15000 fpm is 1.58 times the value mentioned in the AF447 recorded drop of 9500 fpm.

Wonder what you gents think of that?

Last edited by A0283; 21st Jan 2015 at 13:27. Reason: improving layout, add climb/drop comparison, add 7000 and 9500 fpm
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Old 21st Jan 2015, 11:33
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Thanks

Thanks for the table. If this is correct, then things went out of control extremely quickly. Sound very familiar to the AF447 event. However the full reason for this upset is not clear at this point in time, if there was some sensor failure, disconnection of automation, diversion to alternate laws etc. Neither is the state of the aircraft known as it decended, if it still was somewhat controllable as in the AF447 event or if it already had suffered structural failure.
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Old 21st Jan 2015, 11:52
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RifRaf3

Just a reminder that high alt windshear and jet streams are not usually found in the ITCZ region. .... CBs are just plain dangerous in the ITCZ.
Agreed, hence why I tried to distance the "Jetstream" issue from this accident.

However, the same "effect" can be seen circumnavigating CB(s) - the CB itself influences the horizontal W/V (in both drn & speed) - now have multiple large CBs. It is fine for an SOP to say "avoid" by 20NM or whatever, but ATC, multiple CBs and experience can make this impractical or judged unnecessary.
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Old 21st Jan 2015, 13:08
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Non-pilot here again, please bear with me.

What is the possibility that the increase in altitude exhibited by this aircraft was not that at all but was, rather, a corresponding drop in pressure due to the WX the aircraft was in or near at the time?

forgive me if I'm missing the obvious.
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Old 21st Jan 2015, 13:23
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Rgbrock1:

A pressure drop of that magnitude would have to be bounded by a funnel cloud. Tornadoes are atypical in the tropics, and one open all the way through the tropopause rarer still.

There are ample, more common scenarios resulting in a steep climb, the result of the automation's algorithms and the unfortunate coincidence of vertical and or horizontal wind shear.

Soon the FDR data will reveal the various parameters, attained values and consequent flight path. I am not expecting anything too earth-shattering to be revealed. What the industry and regulators conclude from the data is another thing entirely.
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