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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, 04:30
  #2281 (permalink)  
 
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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
  #2282 (permalink)  
 
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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
  #2283 (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
  #2284 (permalink)  
 
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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
  #2285 (permalink)  
 
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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
  #2286 (permalink)  
 
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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
  #2287 (permalink)  
 
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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
  #2288 (permalink)  
 
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Originally Posted by jcjeant View Post

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
  #2289 (permalink)  
 
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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
  #2290 (permalink)  
 
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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
  #2291 (permalink)  
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Originally Posted by Australopithecus View Post
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
  #2292 (permalink)  
 
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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
  #2293 (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
  #2294 (permalink)  
 
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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
  #2295 (permalink)  
 
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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
  #2296 (permalink)  
 
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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
  #2297 (permalink)  
 
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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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Old 21st Jan 2015, 14:20
  #2298 (permalink)  
 
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Cb and Tornado

Emacs thanks for the link,
A0283 thanks or your information,
MrMachfivepointfive for the translation.

Though I had seen in 1982 the original report, after I had left Incident and Accident investigation, I had forgotten the Tornado detail, but remembered the Squall line like frontal system with embedded Cbs.
But more important is the detail of the extreme high accelerations of +6.8 and -3.2 g. It is a very good indication of the inherent forces in those airstream inside a weather build up.

I know from experience that it is a better approach to the truth by waiting for the investigation results, than starting wild guesses and assumptions. So lets wait and see.
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Old 21st Jan 2015, 15:23
  #2299 (permalink)  
 
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Some pages ago someone wanted som number crunching: forces needed, etc. I can't find that post right now, but here are my attempts.

Case scenario: (all numbers taken from Airbus A320 family - Wikipedia, the free encyclopedia)

ASSUMPTION: A320-200 flying at cruising speed 828km/h and 11000m with total weight 78t = 78000kg.

Climb 2000m in one minute = 33,333333m/s = 120km/h

828km/h = 230m/s

Baseline kinetic energy = 2,06e+9 Joule (Nm)

Work needed to lift airplane 2000m = 0,64e+9 Joule (Nm)

Interesting fact is that max allowed speed for A320-200 at 11000m is 871km/h and if some of those 120km/h updrafts added a forward component, an overspeed scenario is likely.

I have deliberately calculated with the max allowed weights and cruising speeds, anything slower and lighter than this would of course be greatly beneficial. I did not calculate any inertia because this would be much too complicated and I really don't have time today.

EDIT: I am very happy to see the Indonesians work so tirelessly and be so committed to this. Awesome effort by the divers, I really hope they get recognized for the extremely dangerous and mentally exhausting work they do. I wonder if there is some way to show appreciation from around the world to those guys.

Last edited by MrSnuggles; 21st Jan 2015 at 15:30. Reason: Forgot brave people...
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Old 21st Jan 2015, 15:50
  #2300 (permalink)  
 
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So far there have been a lot of good suggestions re training for high altitude turbulence, stalling, and even spin recovery. However, as many have pointed out, the first priority is to avoid the extreme weather. There is a long history of jet fighters being lost in large CBs because they lacked any weather radar and yet they were stressed well above airliners' G limits and had much higher control response.

We can't properly simulate really severe turbulence, so the training - as for ditching - has to be rather arbitrary. There is a lot more we can do in regard to weather avoidance at reasonable cost/risk benefit by integrating weather data sources and I hope at least that this tragedy will spur greater efforts in that direction.
....... <snip>
There is a lot of 'noise' in this thread, avoiding the core issue, well written above by RifRaf3 in post #2240.

From my perspective, a humble (former) PPL holder, avoiding the extreme weather, seems to be a minor issue as far as this thread is concerned.

The thinking seems to be that with the aid of technology, experience, and bit of good fortune, a pilot should be able to "thread the weather" (as close as possible), without "getting bitten".

Instead of discussing recovery techniques after the accident, maybe more discussion on prevention ?
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