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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 17th Jan 2015, 08:04
  #2121 (permalink)  
 
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p.j.m (and others freaking out about Indonesia's capacity to respond)

It's concerning if the Indonesian authorities have control of the recovered data, and they have a history of denying an issue if it is something they feel embarrassed about (like a suicide).
So far there has been a very transparent and I think successful response (aside the issue about routes, which was not atypical of bureaucratic responses in more developed countries).

Interestingly when the NTSB gave early briefings on information during the Aseana investigation they were criticised on this forum for too much too soon.

So far the Indonesians have found the wreckage, located and recovered the FDR and CVR in very challenging and risky conditions, have recovered bodies with dignity and respect, are recovering the fuselage, and are providing clear updates on the state of the recovery and investigation. It's an error to use isolated past experiences as predictors of present and future events.

While the families of 9/11 victims still demand to see the redacted 28 pages, and Australia now has a range of new laws which substantially inhibit transparency, I'd say don't throw too many stones.
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Old 17th Jan 2015, 10:05
  #2122 (permalink)  
 
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these planes are sort of constructed in three big pieces...the front part, the middle part and the tail part


so, it seems we have found the big parts and they sort of break up that way.
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Old 17th Jan 2015, 10:37
  #2123 (permalink)  
 
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bud leon is correct - and the Indonesian divers merit special acknowledgment for their outstanding recovery efforts in conditions that are dangerous in the extreme.
Western divers would be looking for bravery awards under the conditions that the Indonesian divers are working in.

These divers have not only been battling strong and reversing currents - they have been travelling out to the wreckage sites in 2M to 4M waves and enduring violent seasickness as well.
They have been diving to extreme depths, at their diving limit. Then they have had to deal with low levels of visibility, as well as the potential finding of human remains staring back at them. It's not a job I'd volunteer for.

They have not had the luxury of ROV's or mini-subs or other exotic equipment, as many Western nations would produce and use.
They have done an admirable job of finding the wreckage and recovering some of it, in surface weather that has been less than favourable, more often than it has been favourable.

Cut the Indonesians some slack, I'm sure they are just as interested in improving their SAR skills, and finding the real reasons behind the crash, as any of us are.

The fact that a few of the middle-management Indonesians got a little excited and made pronouncements that were guesses, more than actual knowledge, is no reason to write off the whole exercise as one of total incompetence.
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Old 17th Jan 2015, 11:28
  #2124 (permalink)  
 
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@ albatross on ‘cylinders’, naming conventions and configuration management

The actual recorders ... have vertically mounted memory-module cylinders ...
My intent was to give a general visual description. It would have been more complete if I had written: “The actual recorders have large diameter, orange coloured, vertically mounted, memory module containing cylinders. With the ‘pinger’ being the small diameter, silver coloured cylinder, mounted horizontally with two black brackets onto two orange brackets on the vertical cylinders.

Note - on quite a few recorders these two black brackets are connected directly to the memory module cylinders. Both actual 8501 recorders have a kind of ‘rather fat’ intermediate orange brackets on which these black brackets are mounted.

There is one ‘pinger’ each on the FDR and the CVR. ‘Pingers’ are better called Underwater Locator Beacon’s (ULB's), But in this case labelled “EMERGENCY LOCATING BEACON” by the manufacturer on the one mounted on the actual CVR. Not smart from the manufacturer to label it like this, as the ELB acronym might easily be confused with ELT. The (some are yellow) ELT is the Emergency Locator Transmitter, which should start its work on impact, and works above the water surface (ref its specific ELT higher frequencies). The ULB should start its work when it contacts(sea)water, and works under the water surface (ref its specific ULB lower frequencies). Seems like a small detail. But naming conventions are a sub-category of what is called “configuration management”. And the (most) advanced state of configuration management in aerospace, being both art and science, is (just) one of the reasons why the industry has become, and is, as safe as it is.

@Archae86 - agreed. Note that his image shows horizontally mounted memory module cylinders. So they are not from 8501. Thanks for the nice and shiny image. Better one than you usually find.

@p.j.m. - agreed. @albatross, note that the boss of the KNKT/NTSC pulls the CVR out of the black container by holding onto the ‘pinger’.
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Old 17th Jan 2015, 11:53
  #2125 (permalink)  
 
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@glendalegoon

these planes are sort of constructed in three big pieces...the front part, the middle part and the tail part ...so, it seems we have found the big parts and they sort of break up that way.
Not always right and not exactly right. But certainly one of the things I look at, from the start of an investigation. In manufacturing they are often called "production breaks". Not always right and not exactly right - and rather simplified - but production break 'lines' are often 'stronger and stiffer' than the areas on either side. So the probability is high that the breaks are on one or either side of these 'lines', and the probability is low that 'through the line itself' is the break. The recovered tail section can be used as a case study. It shows technically important fracturing details.

Note that the production breaks that you mention are on the 'highest level'. Depending on the complexity and design date of the aircraft, there are a number of levels below that. A section break is not the same as the production break/interface of a fuselage panel for instance. This subject is a sub-part of the so-called "interface management". For all kinds of reasons there is a complex relationship between interface management and configuration management. I said something in my previous post about the latter subject.

Let's hope they find the missing passengers and crew in the recently discovered sections.
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Old 17th Jan 2015, 11:56
  #2126 (permalink)  
 
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sunday 12.50 am nz

PANGKALAN BUN, Indonesia (AP) " High waves and strong currents in the Java Sea again prevented Indonesian navy divers from accessing the fuselage and what is believed to be the cockpit from the AirAsia plane that crashed three weeks ago, officials said.

A team of 15 navy divers tried to get to the wreckage to examine it and calculate its weight, but failed to reach it due to the unfavorable conditions, said Suryadi Bambang Supriyadi, director of operations for Indonesia's National Search and Rescue Agency.

Indonesian survey ships have located at least nine big objects, including the jet's fuselage, what is believed to be the cockpit and an engine, Supriyadi said. The fuselage is sitting on the seabed at a depth of 28 meters (92 feet).

The 30-meter-long (100-foot-long) fuselage and an attached wing were sighted Wednesday. Divers attempted to reach the wreckage Thursday and Friday, but were turned back because of the rough sea conditions.

Authorities believe many of the bodies are still inside the fuselage. There were 162 people aboard Flight 8501 when it crashed into the sea Dec. 28 en route from Surabaya, Indonesia's second-largest city, to Singapore. Only 51 bodies have been recovered so far.

The head of the search and rescue agency, Henry Bambang Soelistyo, said Friday that the fuselage would have to be lifted because of the divers' inability to reach it. This will be done by either using floating balloons, as the tail section was lifted earlier in the week, or cranes from tugboats. Soelistyo did not say when the operation would start.

Divers, however, still need to reach the wreckage area. The wreckage that appears to be the cockpit was located by sonar imagery about 500 meters (yards) from the fuselage and was partly embedded in the mud.

"What we have so far is only a silhouette of the wreckage," Supriyadi said. "We need to deploy our divers to identify whether it's the jet's cockpit or something else."

He also said the divers have been told to retrieve the bodies of the pilot and the co-pilot if they are able to find them in the cockpit.
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Old 17th Jan 2015, 12:26
  #2127 (permalink)  
 
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CVR & DFR analysis

Hi there,
How long does it take to decode, visualize & analyse the DFR data ? (flight parameters, engine performance, structural modes,...). I mean to get the rought lines of the failure scenario ?
I have been working several years on tactical missile design and testing.
Knowing how a missile test had failed (in this case knowing whether it was a stall, a catastrophic descent due to a dual engine failure, or how these engine or other structural element failed, etc...) would have been a matter of several hours (if no data is missing/corrupted).

Last edited by Hyperveloce; 17th Jan 2015 at 12:48.
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Old 17th Jan 2015, 13:06
  #2128 (permalink)  
 
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Originally Posted by Hyperveloce
How long does it take to decode, visualize & analyse the DFR data ? (flight parameters, engine performance, structural modes,...). I mean to get the rought lines of the failure scenario ?
If there are no problems with the decoding and timing of the data, the first may take one or two days. The second will take longer. In terms of causes and effects I expect the accident scenario to be quite complex, and the investigators would be well advised not to publish any data before they have at least a rough idea of the causal chain of events.
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Old 17th Jan 2015, 15:23
  #2129 (permalink)  
 
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If they have a good idea of the cause but do not feel it urgent to release any information about it, can it be considered that the likely cause is something that does not pose an immediate risk to the operation of other aircraft of the type?
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Old 17th Jan 2015, 16:07
  #2130 (permalink)  
 
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Originally Posted by quackers View Post
I'm sure most posters will recall the Ethiopian Airways hijacking back in 1996 (Boeing 767) in which 125 of the 175 persons onboard perished. The pilot ditched the aircraft a couple of miles off the African coast, which was a large factor in the survival of 50. The ditching was recorded on video by a tourist from the beach and is easily found via Google.
As with the Airbus, the 767 has engines below the wing and, as the aircraft hits the water the first break-away is the empennage. I believe the cockpit also broke away (both pilots survived). One can only imagine the terrific forces involved when the engines hit the water, acting as massive water dams - hence the transference of stresses throughout the aircraft and its breaking up. The outcome of that incident bears some uncanny comparisons with this latest tragedy in the way that the hull has apparently seperated.

No doubt the true cause of this incident will be revealed during the next few days/weeks but I am of the opinion (for what it's worth) that the aircraft sustained complete/partial electrical & engine failure in the eye of the storm and the pilot(s) attempted a ditching as per the Ethiopian incident. I cannot see that an Airbus can fall from 32,000 feet and break into such large pieces upon contact with the water - at god knows what speed.
AFR447 fell from 38,000ft and the aircraft broke into similar parts as the Air Asia aircraft. The A330 was dropping at around 11,000fpm (125mph) with very little forward speed. The aircraft debris field was more compact as the underwater currents were not as strong, unlike the stormy sea and strong currents in the latest crash.

As A0283 posted earlier these breaks tend to occur close to the strengthened interfaces - production breaks - between major components. This explains the similarity in components of the debris after very different accidents.
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Old 17th Jan 2015, 17:50
  #2131 (permalink)  
 
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Megathron

"If they have a good idea of the cause but do not feel it urgent to release any information about it, can it be considered that the likely cause is something that does not pose an immediate risk to the operation of other aircraft of the type?"

Yes it often can, because otherwise Airbus would issue an All Operators Telex (or whatever it's called these days) which without accepting blame (lawyers!) says "be careful about this".
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Old 18th Jan 2015, 01:21
  #2132 (permalink)  
 
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ELT is the Emergency Locator Transmitter, which should start its work on impact, and works above the water surface (ref its specific ELT higher frequencies). The ULB should start its work when it contacts(sea)water, and works under the water surface (ref its specific ULB lower frequencies)
One more time: ULBs work with SONIC waves and ELTs with RADIO waves. Two different worlds...
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Old 18th Jan 2015, 02:06
  #2133 (permalink)  
 
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@Shadoko - specific frequencies

Quote: ELT is the emergency Locator Transmitter, which should start its work on impact, and works above the water surface (ref its specific ELT higher frequencies). The ULB should start its work when it contacts (sea)water, and works under the water surface (ref its specific ULB lower frequencies)

Shadoko's comment:
One more time: ULBs work with SONIC waves and ELTs with RADIO waves. Two different worlds...
Yes I know. I tried to cover that with the word "specific". I should have written that explicitely as "specific to the use and medium". Your statement is clear and welcome.
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Old 18th Jan 2015, 02:24
  #2134 (permalink)  
 
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@IAN W – on production breaks and AF447

As A0283 posted earlier these breaks tend to occur close to the
strengthened interfaces - production breaks - between major components. This
explains the similarity in components of the debris after very different
accidents.
As I mentioned in my post ... my statement is a simplification ... even with that in mind, I would personally like to adapt your lines a little to something like: “... A0283 post ... these breaks have a higher probability to occur close to the ‘stronger and stiffer’ interfaces, like the so-called production breaks between major components. This may explain similarities in aircraft break-up and components/debris distribution. Even after quite different accidents.” Or perhaps we should say “accidents with different causes”.

In that respect, depending on the type of accident, it could be well advisable to add a manufacturing engineer (which is a special job function, each Tier 1 aircraft manufacturer has a a few) to an investigation team. Their view can add to the views that people with a pilot, design engineer, and maintenance background may not immediately have. Would be interesting to know if anyone has any knowledge of, or experience with this in practice.

Your remark about AF447 made me think back to that accident. The main debris field was only 600x200m, and that at a depth of 3,900 m if I am not mistaken. That ‘compact’ distribution (its an ocean !, and it was in the ITCZ! at that time, and...) still amazes me ... for that depth. Compared to that, relatively speaking, the QZ8501 sections are (figuratively) ‘miles apart’. More knowledge about this might help (even if we do everything to prevent crashes from happening) future searches.
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Old 18th Jan 2015, 02:51
  #2135 (permalink)  
 
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If they have a good idea of the cause but do not feel it urgent to release any information about it, can it be considered that the likely cause is something that does not pose an immediate risk to the operation of other aircraft of the type?
That is a reasonable inference.
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Old 18th Jan 2015, 03:16
  #2136 (permalink)  
 
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Warning reference to QZ 8501 autopsies below.





It has been reported today that autopsies have QZ 8501 passengers revealed impact injuries such as broken legs, but no burns. Source:

Divers sent to investigate pings from crashed AirAsia flight QZ8501 (apologies for mobile link).

I recall that AF447 pax also suffered broken legs from the upward impact of their seats.
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Old 18th Jan 2015, 10:39
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Unlike the AF crash i suspect this airbus hit the sea with some forward speed, cartwheeled and came apart.

I further suspect that this was a weather induced loss of control and at some stage an attempt at recovery was made, but the vertical rate of descent and space between cloud base and hard deck was insufficient

I very much doubt the weather was directly responsible the break up, but if they ended up in a viscous updraft and pitched down and cut the thrust it would be very easy to loose it and recovery in cloud with no visual reference, much turbulence and all manner of warnings going off......there but for the grace of god
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Old 18th Jan 2015, 12:12
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Vertical speed of about 10,000fpm is about 100kts straight down so coupled with 100kts forward it will not be pretty on hitting the ocean!
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Old 18th Jan 2015, 15:34
  #2139 (permalink)  
 
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Future search scenario's

The majority of posters appear to 'vote' for most likely scenario(s) (and versions of those) going like: ‘... an event or upset, leading to a (low speed) stall, no recognition of that stall, or impossible or too late to recover from that stall, and finally the plane hitting the water at an almost even ‘keel’ ...’

I have read interesting comments on other scenario’s though. So I hope those interested in other scenario’s will share comments or suggestions on the following ‘theoretical scenario’.

What would the damage look like, if an almost intact A320 would dive almost straight in?

Keeping in mind the special circumstance in the 8501 case, being that the water is only 28-30m deep. If you take the fuselage length of 37.50 m and subtract the waterdepth of say 29.00 m you get 8.5 m. Now assume that the nose reaches the seafloor. The tail part that ‘sticks out’ is about 8 m. That would roughly be around frame 68-70. Ergo, around the aft strong frame of the aft passenger door?

The exact angle of entry into the water will then determine how the tail section breaks off. Following the earlier ‘production break’ discussion, that could be either just in front, or just behind the aft passenger door. It could also provide a (the section moving ...forward, backward or sideways) break-up scenario for the components of the tail section.

It is possible to think of a path now, that leaves the vertical tail rather undamaged( we can try to match that with the visible fractures – of course trying to exclude damage caused by pulling the tail on board Crest Onyx). And losing the APU and the THS. Where perhaps (see earlier posted scenario’s) the tail section with tail floated before it became water logged, anchored, and overturned. But now the THS also floated before becoming water logged. And therefore it is possible it will be found a bit further away.

I did some tower diving in the past from 10-12 m. When you get in under even a small angle with the vertical, your spine is bent, quite a force, so would fuselage show a kind of water dampened whip 'reflex'. Always very complex to make dynamic stress calculations ... but ...

Answers to these questions might be of some assistence in future searches. Till this accident it seemed most likely, if anything was found on the surface, find vertical tail or rudder first. Would it help to give SAR crews a description of most probably objects to look for. Also helping to separate ocean garbage from aircraft components and fragments.
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Old 18th Jan 2015, 16:04
  #2140 (permalink)  
 
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@ A0283...

Not an expert but if as you suggest the aircraft "went straight in" then one would have to assume it is not in a "stalled" condition, thus probably hitting/entering the water at a substantial speed.

In this case it would most likely break apart in many small pieces upon hitting the water almost like hitting solid ground.

Last edited by Jet Jockey A4; 18th Jan 2015 at 17:07.
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