Air Asia Indonesia Lost Contact from Surabaya to Singapore

[Ian W]

Originally Posted by Ber Nooly

From the CAPE values (around 2000 J/kg) indicated by the model analysis I calculated MAXIMUM updraft velocities of around 55 knots. In reality, rain-loading of the updraft reduces actual velolcities by maybe 30-40%, but let's allow for some stronger outliers too. I still can't see 100 knots being possible, but that's a moot point at this stage.

I realize that I increased the amount of the updraft it was for simplicity of calculation. I still think that the more likely cause of the upset would be the coincidence of a severe updraft and a jump in OAT that would confuse the ADIRUs. If that was linked to sudden accumulation of clear icing from liquid water droplets in the updraft that could block pitot/static ports, then things could get very confusing for both the automatics and the flight crew.

Experts on the Airbus AIDRU algorithms should be able to give an idea on how they could react to:
1. Sudden OAT increase in cruise at FL320
2. Sudden loss of reliable pitot/static information (possibly associated with (1).

The response of the FMC to the AIDRUs could be added to a sudden updraft with a VS of let's say 5,000fpm (to use a value in line with your CAPE values). If the FMC initiated a 'protection' pitch up at the same time as the ambient air was lifting the aircraft at 5000fpm it might explain the apparent unlikely climb rates.

[DrPhillipa]

One interesting line in that news item is "Indonesian transport minister threatens to sack those who cleared QZ8501 for take off when AirAsia was not permitted to fly on Sundays" - not that it has any relevance to why the accident happened.

Or maybe it has, assuming the passenger quota for SUB-SIN was correlated to all the other flights through the area and had something to do with potential safe AC density and separation in an habitually weather threatened airspace.

[AfricanSkies]

The machine has radar. It has multiple sensors and computers. When it sees that it is about to enter a turbulent zone as detected by radar, or indeed enters one, why can't it go into a 'Cautionary' mode where it will be anticipating conditions (large buffets, icing) and react accordingly, instead of not anticipating anything, flying along as if it is blind when it is in fact not, and blithely and stupidly sounding stall warnings when the airspeed drops by a ridiculous amount in an incredible time? If you're going to automate things, then automate them. Don't even display data that fails creditibility tests - it just confuses the pilots. Just pause the game, maintain thrust and attitude and display possible viable alternative data such as INS derived airspeed and AOA* to the pilots, remain engaged using such data but give the crew full unrestricted control if that data indicates flight outside its parameters. Do this until such time that conditions are such that credible data is again calculable, verified with the INS data, and only then display that data to the crew.

Its no use having the million dollar computer display rubbish to you.


*as the INS can describe a FPV then all the factors contributing to that vector can be calculated, even airspeed
(Please do educate me here if I'm incorrect, I'm just a pilot not an expert)

[Flagon]

"Is that not an escape slide?" - indeed, but when detached becomes a 'raft' as per drills.

"not that it has any relevance to why the accident happened. Or maybe it has.." - no - totally itrrelevant. This is a route licensing issue and has zero to do with this accident as far as I can see - a true 'red herring' which could even be 'political' trouble-making by another carrier.

[ATC Watcher]

Air Scotia :

Are those squawk numbers allowed for civilian flights in that airspace?

Yes. Normal SSR codes.

DrPhillipa :

had something to do with potential safe AC density and separation in an habitually weather threatened airspace

Absolutely not. Reason(s) for the Minister agitation is elsewhere, and he is not finished as I heard.

[thcrozier]

ASEAN Open Skies

I understand very little about the ASEAN Open Skies policy, implementation of which is supposed to be complete by year end. But it does seem to be creating some friction between Indonesia and Singapore. That the Minister repeatedly failed to enforce an agreement between the two countries probably puts him in political hot water. Hence this unexpected CYA blame-shifting.

Asean open skies on track - The Nation

http://thejakartaglobe.beritasatu.co...sean-open-sky/

[BigG22]

Ice?

I admit to reading only 66% of this thread so perhaps I might have missed something. Apologies if this is the case.

It is well known that the CFM56 fan is neither capable nor certified to tolerate bird strikes of a size such as occured in the case of US Airways Flight 1549. A little research reveals that earlier CFM56 fan sets suffered from resonance and high-cycle fatigue. And in addition, rain/hail ingestion has also given rise to several incidents with this engine.

Perhaps what is generally less well known is that CFM56 fan blades have been observed to suffer significant damage in the event of ice accretion. When this occurs, high levels of N1 engine tracked order vibration are likely to be observed, along with audible changes in engine 'tone'. The consequences of prolonged engine operation in this condition merit little discussion.

The following report therefore, although not conclusive, contains some degree of credibility:

AirAsia Flight 8501 Crash Possibly Caused by Icing, Indonesian Report Says - WSJ

Are A320 and B737 pilots routinely trained in ice shedding manouvres, and what is the policy for avoidance of potential ice accretion?

By way of explanation, my personal backgound is in aircraft and engine prognostic health monitoring, including engine bird strike detection and fan blade damage detection.

[AfricanSkies]

A thought. Now that accellerometers are so tiny, would it not be possible to mount sets of them at each extremity of the aircraft (nose , tail, wingtips) and then calculate a graphic representation of the aircraft's movements in space? Could be presented to the crew as a 3rd person view perhaps?

[nickp]

Thanks IcePack. It was a simple question - can I set the a/c up at turbulence penetration speed/mach, power and attitude and the a/c will then maintain power and attitude and ignore any other sensor inputs?
I get the impression the answer is 'no', because the various protection systems will kick in.

[etudiant]

A question for those who know A 320 cabin sidewall materials.
There was an image earlier in this thread of a damaged sidewall, including the window surround, that was recovered at sea. The sidewall was neatly cut across the top, is though it had been sheared.
Is there anything other than high speed aerodynamic stresses that can shear a composite structure so cleanly?
It seemed to me that this bit of debris was pretty strong evidence that the aircraft had broken up in flight. Is this a mistaken belief?
Certainly the absence of any cockpit communications during a long fall from 30 odd thousand feet is more consistent with a catastrophe than an icing/loss of control scenario.
After all, they were in ongoing ATC communication, unlike AF447.

[MrSnuggles]

etudiant.

As I answered to the original poster of that picture, we need to see the adjacent structure to make any claims of any sorts.

This type of damage can occur in many ways. One of the many ways may be that when the plane hit the ocean the forces made the bottom half snap cleanly from the wall structure but the upper part may have been stuck by, well, let's say, an overhead cabin and thus the crumbled upper part. This is just one of MANY explanations for this. Please remember that.

[HarryMann]

Etudiant

anything 'other' than high speed aerodynamic stresses that could do that,?

Whatever you mean by high speed aerodynamic stresses... lots of things could. A kniife like object striking it maybe...

Water is hard when struck at any speed.
Depending on how an object is supported acceleration or deceleration alone can achieve surprising things. Aerodynamic s doesn't have to come into it, high speed or not
so proof of nothing yet IMHO

NB. Aerodynamic Forces create stresses (and strains) on objects... per se there
is no such thing as an aerodynamic stress, other than maybe between molecules
of air.

[AirScotia]

The debris found shortly after the AF447 crash showed similar characteristics, and that was high velocity impact with the ocean. The cruise-level destruction of MH17 resulted in much smaller pieces (apart from engines) and fragmented bodies.

[ekw]

Slats11, your economic model is a little off. It should be Revenue - (Fixed Costs + Product Costs) = Profit. The biggest fixed cost savings which LCC find is in operating from cheaper airfields. They will only operate from expensive airfields when loading is always high (e. g. Hong Kong). Through clever hedging they might save on fuel as well but that can be a double edged sword. Whilst staff costs are cheaper in Asia than in Europe, there is no difference here between legacy and LCC carriers. Both pay peanuts for ground staff and cabin crew but both have to recruit internationally for the flight deck and maintenance. The real savings are in product costs. LCC try to achieve higher turn around times and higher efficiency by removing services which are not required in order to perform the contract of moving the customer from A to B. The inference that LCC are compromising safety is not accurate because if they were, their insurance premiums would move in tandem, killing their profit. Allianz actuaries will be sratching their heads trying to figure out why Malaysian* airlines are now such a big risk. 3 crashes yes, but no obvious link.

*Air Asia Indonesia is controlled by its parent, Air Asia notwithstanding that for political/legal reasons an Indonesian investor appears to own 51%.

[etudiant]

Thank you for the considered replies.
I spoke of high speed aerodynamic because in my limited experience, composites rarely snap cleanly as they did here, they usually have bits sticking above the line of separation, unless the break is very forceful and sudden. That plus the abrupt silence of the crew together are pretty significant, imho.

[Propduffer]

@Machinbird

Here is a KML file which expands on my post 1197.
Plug it into Google Earth and you will find the FR24 data plotted, showing the actual coordinates along with the debris locations etc.



https://www.dropbox.com/s/8j2tl52m5d...08501.kmz?dl=0

[Leightman 957]

Part ID

Clips on this piece have been noted previously. What is top and what is bottom?

I answered my own question: clips are at the panel top as suggested by A320 photos showing a radius on the panel concavity below the window. Panel bottom torn, top undamaged.

[ettore]

'Crashed AirAsia jet's pilots did not get weather report' according to Jakarta Post

'Crashed AirAsia jet's pilots did not get weather report' - The Economic Times

Sorry if already posted. If true, I'm stunned

[McWho]

The only window I've seen is a plastic panel which is undamaged at one end and torn at the other. The wind probably tore it from its fixings. Would all passengers please replace their tin foil hats.

Given that the fixings in the bottom of the photo have hooks pointing up, I'd imagine that's the top. We can all rest easy knowing if we get bored on our next flight we know how to annoy the cabin crew by dismantling the interior of the aircraft.

[etudiant]

'Crashed AirAsia jet's pilots did not get weather report' according to Jakarta Post 'Crashed AirAsia jet's pilots did not get weather report' - The Economic Times

Sorry if already posted. If true, I'm stunned




Seen that there were other flights shortly ahead of him, behind him and to either side of him, it would be surprising if any weather reports would have changed a thing for the pilot of 8501.