@ 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.

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 ?

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.

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.

It wont just be the Indonesians looking at the FDR and CVR information. There will be Airbus reps, Australian FR/CVR specialists etc.

I'm not sure who "we" are but the official report should be able to provide that info. The public does not have a right to this stuff before the investigators complete their work.

I agree. I think all must understand that Indonesia has a new, highly progressive President: Joko Widodo. It is in his and the countries best interest to improve air safety in Indonesia and repair their image abroad.

Corruption runs rampant in Indonesia, and it seems that this has been unearthed in the Aviation sector. Expect major clean-up, including criminal investigations by the highly effective KPK (corruption eradication commision).

Not really. Flimsy plastic lifejacket containers designed to be opened in a hurry are not going to be crashproof. Aircraft accidents have been known to strip layers of clothing off people.

I haven't seen the photo, but perhaps it was an attendant's demo life vest? ;)

@glendalogoon: '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'

Tony Fernandes (Air Asia) is not an idiot. He's running a sophisticated, international operation.

Hydrodynamic forces in accidents
 

If you want an insight into the forces and effects involved, have a look at this crew:

-The Bluebird Project | Home

They have done an astonishing job, and that includes very detailed forensic analysis of what happens when water meets metal at high speed.

(It's a fascinating project and website in any case)

Do you mean this photo? (cropped)

Sorry, I don't find it interesting at all considering the condition of the wreckage.

http://i2.photobucket.com/albums/y17...6.jpg~original

It is very hard to imagine that a horizontal stabilizer fails due to overload (or a "hand").
Having significantly less span than the wing, high "twisting" loads due to roll are impossible, the wings will stop the aircraft rolling fast enough to create significant loads on the stabilizer.
Any high up or down forces would immediately result in big AoA changes, at cruise speed that would mean enormous g-loads, which would most probably rip of the wings before the stabilizer.
So the only aerodynamic scenario I could call remotely likely would be an asymmetric actuator fault, meaning one elevator deflecting up and the other one deflecting down (commanded by the computers to counteract the pitching moment caused by the faulty actuator). Given the fact that there are two actuators per elevator, and we never experienced such scenario, I would not consider this likely.
Thinking of the Alaska Air trim actuator accident, a scenario like that might be possible, but that would have most likely also resulted in an in flight breakup and a much wider field of much smaller debris.

So I do (so far) not believe in any horizontal stabilizer failure scenario. It all looks more like the Aircraft hit the water first with the tail, which caused all the damage.

With respect to cutting the tail section, I found the upper skin panel just behind the pressure bulkhead very interesting (don´t have the link to the photograph currently): All stringers are buckled, so obviously there has been high up-bending loads on the tail. Either due to high forward momentum from the VTP with high horizontal deceleration, or due to impact forces on the tail from below, indicating an impact with high AoA. Cutting in that area is probably destroying some evidence...

We have codification not only in transport but currency, food and many other areas of life because there have ALWAYS been 'cheapos', scammers, fraudsters and the rest of them. Don't kid yourself the past is a halcyon period where everyone did everything right without scrimping. Some areas it hurts the pocket, others it has often been lethal - food for example.


BBC News - 10 dangerous things in Victorian/Edwardian homes

A real time empennage failure from the archives...
 

For those of you born too late, Google "MD 80 test flight crash" to find a youtube video of a intentional hard landing. The tail separates, and that's at about 1200 fpm descent from memory. Imagine hitting water instead of a runway with the gear down and its not too hard to expect to see exactly what is being seen in this debris field.

If the EASA emergency AD relating to blocked AOA probes is relevant then this investigation could get very messy. I guess we will know soon enough.

What, exactly, does "trying to decode" mean?

An important learning point for SLF arising from the Ethiopian crash off Comoros mentioned above (Ethiopian 961 in November 1996) is that there were a few survivors, but it was reported that many more might have survived but that they inflated their lifejackets before exiting, so couldn't get out (and probably blocked others). We're always told "don't inflate before exiting", and that's why,.

The DFDR memory module contains a long string of 0’s and 1’s, called “bits”. Twelve bits comprise a “word”, many words are contained in a 1-second “subframe”, 4 subframes form a “frame”. The meaning of the thousands of words in a frame is defined in a “Decoding Document” that is submitted to the authorities when an airplane obtains it registration. The first word in each subframe contains the date and time of the subframe. Each of the subsequent words is dedicated to one or more of the thousands of parameters recorded.

In addition, before you can get to those 1s and 0s, you need to decompress the data, which is stored in a special and proprietary format which compacts the data to be able to store as much as possible in as small memory as possible.

The decoding document above is basically an OEM thing, but the FDR manufacturer is the one who knows how it's compressed. that's another set of special software required, with the right decoding info too.

I believe the 9/11 truthers have been trying for 12+ years to decode one of the "raw" FDR files from one of the aircraft that they somehow acquired, with no success because no-one who knows how to do it - which is a pretty closed community - has any interest in providing the information required. In this case, it's won't be the same reluctance, but it's a bit of an art, so if you've never done it before, even with the right info it might take a while ...

Importance of locating ocean crashed rapidly
 

Quite some number of contributors have expressed the opinion that location of wreckage after and ocean accident is not particularly important. These opinions also extend to the relative importance of investigating the primary cause of the incident versus the blow by blow analysis of every aspect.

I think these attitudes are probably statistically appropriate, but they do not accurately reflect the general consensus and policy that has been adopted more or less since the start of aviation.

The statistical chances of surviving ditching in the ocean are very small. Yet, every passenger aircraft has life jackets, rafts, passenger safety briefings and so on. Clearly, it is the intention of the air travel industry to give the passengers at least a reasonable chance of surviving a ditching event.

In those circumstances, I find it extremely difficult to understand why a practical and effective systems to locate ditched or crashed aircraft have not been mandatory for many years. If you survive a ditching you will not survive for long in the ocean without rescue. Surely location is a vital ingredient? In addition, a collateral benefit would be to reduce resources being wasted on SAR.


For those that suggest that it is difficult or impossible to design an effective device for locating an ocean crash site; I would suggest you are as wrong as wrong could be. It would be a simple project even in grade school.


If it is our intention to abandon aircraft and passengers at sea, in the event of ditching, then please remove the emergency safety equipment and stop these pointless passenger safety briefings.

For the scenario you draw up, there are ELT's and rafts. A survivable water landing and successful exit has been provided for. Now, is it sufficient to the task? In New York it was, but that was not "out at sea" but on a river in the biggest city in the nation. How many at sea ditchings have happened in the last 40 years that were survivable? What were the cues that got search and rescue teams to the location?