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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 14th Jan 2015, 20:56
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Aerodynamic and Hydrodynamic etc

@A0283:


With respect, nothing that I have seen so far leads me to believe that the main body of the aircraft was separated from the aft section prior to impact with the surface of the ocean. If it had separated then one would expect to see a more intact empennage; no burst bulkhead and more of the aft floor section still attached, or some remnants of floor frame. During a water impact, the hydrodynamic scour that occurs forces the floor section upwards, and in the process causes it to become detached from the side frames exactly what we see in this instance. Ok, the floor frame complex could have pulled out in one if aerodynamic separation was the cause, but that still does not explain the burst bulkhead. The most likely reason for the distance in separation is probably down to the fact that since this part of the intact aircraft probably made first contact with the water ( ie: the aircraft is in a pitched up attitude), the break that occurred between it and the main section was well developed by the time the lower skin of the the main fuselage failed, thus allowing hydraulic surge (impulse) to flow through the cabin in fractions of a second, particularly to the now open ended rear scouring everything in its way. Given that the APU and other heavy bits appear to have detached, plus maybe some level of buoyancy remaining (inflated rear exit slide ) in the aft section and a 5k current, it is not difficult to imagine the aft section drifting apart from the heavier main body. The rear end of the fuselage, as seen in latest photo, appears to show floor frames presumably pulled out from the missing aft section once the connections to the side frames failed. There is also the evidence of one of the data recorders being found under the wing. If the aft had detached in the air, then is it probable that the recorder be found under the wing?

Chronus: The terms used in the literature (NASA Langley Research Center vertical drop tests) for an airframe impact with water are often referred to as Hydrodynamic impact loading. In the past I have also come across the terms Hydrodynamic Ram effect or Hydraulic surge.
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Old 14th Jan 2015, 20:59
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Can anyone tell me if there has ever been a failure of the empenage in ANY Airbus Product? ;-)
American 587 is the most obvious with an in-flight loss of the VS, although in several instances (AF447, Perpignan) it was found floating alone after impact. Of course, that's not the full empennage...
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Old 14th Jan 2015, 21:15
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In this instance my money is on the in -flight loss of the empennage as a result of aerodynamic forces imposed upon it beyond its structural limititations
Basic stability means there is a downforce on the horizontal tailplane.

By definition therefore, if the horizontal tail is lost (as you say), the aircraft bunts - hard. Significant negative 'g'. In turn this would likely lead to a very high speed, near vertical impact. Not sure the wreckage supports that at all?

In fact, loss of tailplane can impose sufficient negative g that the wings then fail.
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Old 14th Jan 2015, 21:43
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Grrr re bj-eng

your 14th Jan 2015, 12:56 post
evidence of one of the data recorders being found under the wing
I suspect that report was made by someone strictly based on the shape of debris it was under. After all, the horizontal stabilizer is shaped very much like a wing and works the same way. To the casual observer or from a underwater photo of part of the structure, the differences would not be obvious without some sort of scale or other information.
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Old 14th Jan 2015, 21:48
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"Most comments on stalling are by those who have never stalled a swept wing jet at high altitude except once or twice in a simulator....."

Before we even get to attempting to practise stalling, in sims of dubious fidelity, how many airline crew posters on this forum have NEVER hand-flown their 'frame, at max mass for the max cruise altitude for that mass?

The "bungee cord" flight controls effect plus the momentum versus control effectiveness is indeed impressive, as is the "fright factor", in S&L controlled flight.

Yet I get the impression, due to some perceived prohibition on hand flying in RVSM airspace, that there are out there now, both F/Os and CAPTAINS who have never controlled their allocated craft in such conditions.

If this is indeed true, then we're all on our way to hell in a handcart if that is the xAAs and airline training departments' official policy.

Please, those of you out there still practising the art of airframe manager, prove to me that I'm wrong, and that EVERY current airline pilot has had the opportunity to hand fly a line aircraft full of SLF at max certified altitude/mass until he/she/it are fully aware of and comfortable with the handling characteristics.

If there are any exceptions to this fun experience, may I challenge whether that is a sensible state of affairs?

Which begs the question, per airframe kilometres/nautical miles, are we seeing a real increase in high-altitude LOC incidents/accidents since the introduction of RVSM and the perceived lack of practice in this environment, or is it just my (false) impression?
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Old 14th Jan 2015, 22:02
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More pictures there in the link.

Pictures & News Photos | Getty Images
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Old 14th Jan 2015, 22:05
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Photo citations

Would those posting photos please cite the source address? Thank you RetF4.

Tail location where discovered is no strong indication of impact location. Partial bouyancy, highest just after impact, is all that is required for drift. With any buoyancy at all the assembly would have been a vertical sail in the current. Some corroboration would be the current direction. Distance could be nothing more than rate of loss of buoyancy until seabed anchoring overcame current.

Last edited by Leightman 957; 14th Jan 2015 at 22:19. Reason: buoyancy rate
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Old 14th Jan 2015, 22:26
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Barking Mad wrote

"Before we even get to attempting to practise stalling, in sims of dubious fidelity, how many airline crew posters on this forum have NEVER hand-flown their 'frame, at max mass for the max cruise altitude for that mass?"

I have never done that in my current bus for the stated reasons and SOP and for reasons of both practicality and courtesy to my passengers. If I ever had to it would be briefly while clearance to a lower altitude was acquired. I do it in the sim from time to time, but only for a few minutes between tasks.

Having said that, in normal law in smooth conditions it is easy. Add complications and it becomes harder quickly. Add cognitive overload and it becomes very hard indeed.

I have hand flown several other transport jets at max level for prolonged periods without problem, but that requires a current agile scan rate and younger reflexes to make it appear effortless.
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Old 14th Jan 2015, 22:45
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Interesting to see an unpackaged life vest in the new photo thread from previous post
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Old 15th Jan 2015, 00:10
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Replies to posts

RE various posts:
FDR CVR recovery will tell some things about what the aircraft did, and what the pilots did, but not why the pilots did it, which is what prevention really needs to know. What 'new' money would be assigned to finding why pilots acted as they did in future incidents?

RE Algol, last seen at #1966 (though currently pg 99 will not load): ”Having seen the aircraft after the event, and spoken with my colleagues, it was no ordinary CB. NASA commented that the flight probably only penetrated the outer edges before they turned/got spat out. They also speculated that further penetration would almost certainly have resulted in a breakup.”

Virtually all forum comments to date treat cb's as dangerous but infer some kind of ordinariness about them. A quote such as “There are cb's in Europe too” infers European cb characteristics are within a range of characteristics that include ITCZ cb's, enabled by a wide but vague inclusivity of cb characteristics, that also manages an equally wide acceptance of moisture complexities near the equator.

Re FullWings perma:
http://www.pprune.org/rumours-news/5...ml#post8825000
“You had to agressively reduce the AoA by pitching down to a far greater degree than in any other flight phase.”

Given the factors of narrow cruise speed range, limitations of live weather info, and inability of aircraft or pilots from recovering from wx caused or faulty instrument upsets outside of a narrow AOA range, 'more training' suggested by many seems to offer very few benefits.

Last edited by Leightman 957; 15th Jan 2015 at 16:21. Reason: Reduced suggestion of conjecture
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Old 15th Jan 2015, 00:20
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I personally am far from certain the accident was even related to a CB. Maybe, maybe not. We are only days from knowing the truth, I would refrain from spinning theories that may have little to do with reality.
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Old 15th Jan 2015, 02:05
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porterhouse:


I am personally am far from certain the accident was even related to a CB. Maybe, maybe not. We are only days from knowing the truth, I would refrain from spinning theories that may have little to do with reality.
You are "spot on" as to what caused the accident.

Having said that, I remain skeptical that we will learn the truth considering the country that has the recorders.
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Old 15th Jan 2015, 02:13
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As yet, we don't even know for sure whether there were two functional pilots in the cockpit at the start of whatever chain of events led to this catastrophe. The greater probability is that there were, but nothing can yet be ruled in or out in that regard.

All we know is that a seemingly very experienced captain in terms of handling conditions in that part of the world, and his FO, ended up in the drink.

I hope the interpretation of the FDR and CVR is more accurate than the head of Barsarnas has been of late.
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Old 15th Jan 2015, 02:27
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aterpster

I just learned that indonesia is trying to decode the boxes themselves instead of sending them to established and respected labs in other countries.

Highly disturbing.

I am unaware of how things work in that part of the world. But would always like to know how money is flowing, from who to whom...if the cause of the accident completely exhonerates the airline...wellllllll
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Old 15th Jan 2015, 02:32
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Photo from NY Daily news

Photo from the NY Daily news purports to show an "Airbus Investigator". Interesting, rather low profile.

http://assets.nydailynews.com/polopo...a-airplane.jpg
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Old 15th Jan 2015, 02:33
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I remain skeptical that we will learn the truth considering the country that has the recorders.
I disagree, I think we will learn the truth, Indonesia did have their share of air accidents and their investigative body each time did sufficient job. Perhaps their final reports are not as polished and comprehensive but no one ever questioned their main results.
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Old 15th Jan 2015, 02:37
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@ BJ-ENG - Aerodynamic and Hydrodynamic etc

Latest official information is that both recorders were found under the right wing and/or right wing/fuselage combination.
Latest official information states that only the right wing was located.
Officials have not provided information on the left wing, the cockpit, or the second engine. Spotting the first engine was mentioned earlier. But there is no mention of actual location yet.


BJ-ENG. Thanks for your reply. You introduce some interesting points that I would like to look at.

Before doing that, my line of thinking on water landing (before I read your reply, so there may be some duplication in it) was roughly thinking about two different and both basic scenarios.

First scenario, the pilots somehow regained control after losing it (losing it for whatever reason). Then they would probably try a ‘mild’ pitch up approach (would be interesting to know what kind of procedure AirAsia has for water landings). Which might lead to a ‘tail separates first’. The Hudson landing was one of amazing airmanship, but luckily not in ‘open water’. Even there, significant tail damage is visible (there were some good posts on that earlier, thanks). Damage that looks similar but, at first sight, not of the ‘same type’.

Second scenario, they did not regain control, or not enough. Which would probably lead to a ‘one wing first’ (there is quite a swell in the area...), followed by a slam on the water, leading to a break ‘somewhere forward of the wing’, and the - by then rotating aircraft (along the longitudinal axis) - losing the horizontal and thereby wringing the lower part of the tail section off.
The widebody jet crashing close to a beach in Africa was not recovered as far as I know. If there is information, that would be interesting.

The second option appeared more probably to me. It would also explain something of the ‘giant hand’ damage on the aft section, pressure bulkhead and some other parts. What made it less probable – at least to me, and until now – was that I would expect the second scenario to lead to quite a different debris field from the one we have. A surge through the fuselage would sweep out a lot of material that floats. Hope you can give your views on that.

Also hope they find the cockpit and the other wing, which will tell us more.
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Old 15th Jan 2015, 03:12
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Debris Field Map

We need a detailed large scale Debris Field Map/Chart, with accurate coordinates.

There has been plenty of time for the Navy to publish an accurate and up to date one.

I can not find one.

Does anyone have one, or a link to one, other than the basic one posted a few days ago ?

With regard to the airframe itself, it seems very odd that all that seems to have been located so far is the tail, cvr, fdr, and the central part of the wing/fuselage. So far as I can gather, three of the traditional four corners are still missing, the nose, and both wing tips. What about the main engines and pylons ?

The reports that the cvr and frd were found with "the wing" is odd.

The ths looks like a wing to most people, especially to a navy diver in the murky depths, or perhaps it is a language translation issue, perhaps even a "jounalist" issue.

It seems likely that they were with the missing sector of the pressure bulkhead, since they were attached to the structure right next to it. Did that part, remain with the bottom of the fuselage as it fracured longitudinally, and subsequently folded under the remnants of the rear fuselage and wing as it sank and settled on the bottom (in which case the "under the wing" may make sense and be correct), or did that section separate and go with the ths, apu and the remainder of the bottom of the rear part of the empenage ?
So, have they found the ths and/or apu or not ?
Can anyone clear that up ?

Next point.

An engine has been mentioned, but which engine, and where is it ?
Was it the apu ?
Was it a main engine ?
If so, where is the other main engine ?

Why have they apparently wound back the search as reported ?

Are they assuming that the recoders will tell all, so no further recovery is required ?
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Old 15th Jan 2015, 03:29
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As HarryMann said a few pages back, anything is possible hitting the water at anything over 100 knots airspeed. A wing low at impact could cause a cartwheel, breaking off the tail, cockpit, and a wing which all float and then sink at different rates being carried by the current.
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Old 15th Jan 2015, 03:43
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I just learned that indonesia is trying to decode the boxes themselves instead of sending them to established and respected labs in other countries.

Highly disturbing.
Why? It's exactly what they did in the Russian crash two years ago.

https://en.wikipedia.org/wiki/Mount_...rjet_100_crash

I won't say the report was the best thing I've ever read but they did a good enough job with it. I have full confidence that the Indonesians can handle this crash investigation properly.
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