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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 11th Feb 2015, 20:37
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Ok465
Thank you for your point of view, which is a valid one and it was not my suggestion to train the stuff like we did in UPT. I hated stalls and falls from the beginning and could not understand, how some could love that uncoordinated falling.

There are three effects influencing a successfull outcome, the procedural part, the type specific part and the physical part. While the first two can be trained in classrooms and present simulation systems, the physical exposure to the forces in a stall event from entry to successfull recovery can not be replicated in present sim, at least not that I know off. The german military uses one centrifugal gadget which is good for positive g loading, but afaik no good for the opposite.

My line of thinking concerning the failures in multiple accidents to break the stall by putting the SS or control column to the forward stop when necessary is, that the effects such an input would have during normal flying is preventing the crew to even think about it or to maintain that input long enough. There must be reason for that, and it is human not to deliberately go into unknown territory. Therfore as soon as some unloading is expierienced like it happened in AF447 case (see the Nz graph and compare it to the following pitch control input), it is followed immidiately by the opposite input to get rid of this unfamiliar unloading.

Exposure to such an maneuver in any suitable aircraft will aid in more tolerance to this physical effect and would provide some knowledge what to expect during such recovery. The real problem is, that this "Angst" already influences the early avoidance of stall entry in a negative way.

The sim for such training is just a box, a very clever one which can trick the senses in believing all kind of movement, but there is none where the g loads are generated in a usefull way. We all know that transport aircraft should be flown with minimal loadfactor changes, smooth and comfy for the passengers and that's the way aircrews are trained. But that does not help at all in approach to stall and stall recovery events, as the near past has shown.
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Old 11th Feb 2015, 20:44
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RetiredF4, that's an extremely good point.

I think an interim measure could be to ensure stall training includes a well emphasised disclaimer that reduced G-force is likely to be experienced during recovery, which the simulator can not represent adequately.

It shouldn't be a stretch for most pilots to then make the link that the feeling of reduced loading confirms the efficacy of the maneuver, which is designed first and foremost to unload the wing.

The best way minimise the psychological effects of the unexpected, is to make it expected (or at least plant it somewhere in the back of the mind).
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Old 11th Feb 2015, 20:56
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some of you chaps are talking about very aggressive maneuvers to recover from a stalled condition. Once you've unloaded the aircraft to zero G and the angle of attack is accordingly reduced it can't be in a stalled any more. Obviously you then need to wait for the aircraft to accelerate but I don't really understand why shoving masses of negative G makes any difference. But the problem appears to be much more basic than that. Experienced guys are not making any kind of stall recovery - in the case of 447 it appears they didn't even realise they were stalled. Assymetric power, rolling to knife edge, mucking around with the gear and whatever else has been suggested may be a technique that Chuck Yeager would use when all else fails but surely a stall recovery should be relatively simple for any pilot. Recognition is the problem, not recovery. I am an average pilot and I am shocked that other blokes like me can get so overloaded that the bloody obvious is not a possibility they consider. Surely, if it can happen to them, it can happen to me and most of you. Its not the ability of the blokes to fly the recovery - its the recognition of whats going on
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Old 11th Feb 2015, 22:07
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tommutrie
some of you chaps are talking about very aggressive maneuvers to recover from a stalled condition. Once you've unloaded the aircraft to zero G and the angle of attack is accordingly reduced it can't be in a stalled any more. Obviously you then need to wait for the aircraft to accelerate but I don't really understand why shoving masses of negative G makes any difference.
Let me point out some misunderstanding here.

Nobody is talking about masses of negative G. The aim is 0 g, as that will take the load off the wings and unstall the wing regardless of airspeed. 0 g is however a big number for someone, who has never expierienced less than +.9 g by his own hands in his thousands of flying hours. From the physical stress we could compare it to pulling +4 g, as positive g' are more tolerable.

0 g is not reached by gently putting the SS or the Control column a bit forward of neutral when stalled already. That kind of control input might be sufficient in the very early state of an entry into the stall when the AOA is close to the max allowable AOA, but it will achieve nothing when the AOA is excessive. Depending on different factors the AOA will decrease very slowly ( and the load factor in turn as well) even with a full nose down pitch input, which then has to be gradually released when the AOA decreases. Once the 0 g, representing 0 AOA is reached, maintain it with whatever control input it takes until the airspeed is sufficient again for recovery.

Maybe we should use a differnt word for agressive, I think I tried to avoid it in my arguments, let' s call it a decisive maneuver, an immidiate reaction to the stall warning with the correct procedure to migitate the danger to drop deeper into the stalled regime while accepting that management and passengers will not like the fallout of such a maneuver.

Last edited by RetiredF4; 12th Feb 2015 at 10:21.
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Old 11th Feb 2015, 22:14
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Expectations vs reactions

RetF4 thanks for your several well thought out posts. But your conclusion that early stall avoidance may require uncomfortable and never before experienced sensations (dirt, papers, coffee, and appendages rising) that will in many or most people inhibit proper actions appears to me to seamlessly morph into a prediction of lingering angst resulting from any exposures to sub G training "in any suitable" AC. You term these physical benefits as improved "tolerance", 'tolerance' suggesting an increased ability to withstand a discomfort. Perhaps my sub and negative G introduction and subsequent investigation was different, and that probably people in general will have widely varying reactions, but I think a distinction should be made between "tolerance" and "familiarity".

I may learn to become tolerant in the dentist's chair but I don't know if I will ever become as able to act with as much speed or finesse or total SA sitting there with the drill screaming if the chair also jumps off the floor, the building begins to sway, and the fire alarm goes off. "Familiar" however implies a reaction where a sensation has become so well known that the fear of it or angst about it has been surpassed. (However I don't suggest that training to familiarity in the dentistry illustration would ever reach a place of personal ease:-)

I realize I am drawing a fine distinction here, but I don't think it is negligible.

I know that if I had a choice between a pilot who I knew tolerated sub or neg G, and one who was entirely familiar with it, I would choose the latter. I also know that if I knew one airline for which zero awareness or minimal tolerance was the norm, and another where all aspects of piloting were encouraged to be explored for all anticipated flight regimes, I would also clearly choose the latter. It has come as something of a surprise to me to find that the airline industry has evolved to systemically include as much aviating slack as has been reported here.

High altitude stall events as under discussion now are rare, but I don't see that at as any reason to avoid comprehensive training covering anticipated flight regimes, especially when once a stall has been entered there is along with a lot of brand new potential circumstances, a relative dearth of Plan B's. Training today certainly includes other equally rare events that are thought to be essential. Acro aircraft and pilots looking for any excuse to bore odd shaped holes in the air are sprinkled everywhere around the globe everywhere and are cheap compared to dredging the occasional large aircraft. I'm not suggesting acro sequence training for everyone. All we are looking for here is a cheap effective erasure of angst. But like any piloting skill, such exposure demands currency.

Cloudcutter suggested that an intellectually (not physically) informed anticipation of a set of sensations will be sufficient. My experience taught me any never-before-experienced sub or negative G sensations, particularly combined with stress, is going to leave one less able to respond no matter the amount of intellectual preparation.
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Old 11th Feb 2015, 22:40
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Most of this discussion seems more AF447 related, given the lack of information regarding the accident this thread refers to.

tommoutrie makes the point that the issue today is more the recognition of the stall. Not the recovery.

Airbus and Boeing have tightened up their stall recovery techniques and they aren't really the issue here.

Certainly in a Boeing it is very simple:

Push down trim down until the stall indications stop.

Unreliable airspeed is also pretty clear cut now:

If in doubt straight away set a specific attitude and thrust setting then troubleshoot.

Recognition and prompt CRM and action is the issue, not the recovery technique.
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Old 11th Feb 2015, 22:58
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Stall diagnosis

Failure to identify stall is indeed remarkable. You have highly qualified pilots looking at stall warning lights & sounds, crickets, an PFD pointing up 10 deg, airspeed decaying to below 60knots, vsi max'd down, altitude tape unwinding like you never seen before. What else can the a/c possible do to tell you?
Some have suggested a stick shaker, then pusher. Not convinced that that would help or just add to the confusion.

Last edited by xcitation; 11th Feb 2015 at 23:25.
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Old 12th Feb 2015, 00:00
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One A320 simulator training syllabus included setting up the aircraft for practice stall recovery with ALT LAW.
The high altitude part was conducted clean at 25,000 ft. Hardly "high altitude"I would say.. The next was conducted first at 12,000 ft clean and then in the landing configuration at the same altitude. Nothing in the syllabus about IMC or VMC. To be realistic it should be in IMC where manual instrument flying skills would form part of the practice.

In view of recent loss of control events in Airbus aircraft which happened around 35,000 ft or above, it could be argued that stall recovery practice in the simulator should be conducted at that altitude or higher. After all that is where the accidents started.

Practicing a stall recovery at 12,000 ft in the landing configuration seems a trifle illogical since very few airports taking jet transports are that high. It would be more logical to conduct a landing configuration stall recovery on short final since recovery requires minimum loss of height for obvious reasons. As most pilots are aware, stall recovery technique is entirely different at high cruise altitudes compared to (say) 800 ft agl when the aircraft is in the landing configuration.
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Old 12th Feb 2015, 00:14
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Centaurus, trouble is the Sims (in general) are not programed to be representative at 35000 they handle the same as they do at 15000. + the stalls are not representative eg hold full back stick on a 330 sim at 35000 with an aft cofg (38%) and after some buffet the nose will drop. I.e conventional stall. But we know that this is not the case. IMHO this is criminal. Much of the stall teaching on sims is negative training. & no you can't do it for real as the aircraft "might" break if mishandled. So how would the crew really know what to expect of a FBW stall. I certainly don't (I can guess) & I've been flying them for 10 years or so.
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Old 12th Feb 2015, 13:37
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Back on topic for a moment..

Stall speculation aside.

When is the actual preliminary report due out? I thought it was late Jan?
Due to the fact they were keen(maybe not he best word) to cancel the majority of the salvage operations, surely the investigation team have a clear picture with the aid of FDR/CVR of what happened?
If so what's with the delay?
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Old 12th Feb 2015, 14:29
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An airframe every year or two falling out of the sky from cruise killing hundreds.
Sims not accurately programmed to train for scenarios that can and do happen in extremis.
Is it time to fit an ejector seat in an old 319/320 airframe and possibly also 330 and send a test pilot up to find out what REALLY happens. What the plane really handles like. What the recovery techniques all current pilots on type would lead to if done expeditiously. And not.
I'd prefer a man with an ejector seat to find out on his own that "putting 90 degrees of bank angle on to drop a wing and get the nose down" can be done, retains control authority an structural integrity. Rather than when I'm sat in seat 9A reading my book and planning a nice weekend.
Just saying...
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Old 12th Feb 2015, 15:12
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If the aircraft requires an ejector seat for pilot safety if it stalls/spins then I am not sure it should be certified as a commercial airliner.

Test pilots have deliberately test full-stalled various airliners without a bang-seat in the past, so it is something that can be done.
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Old 12th Feb 2015, 15:20
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Test stalled sure - but at or close to service ceiling? With a simulated full load, an imperfect trim with rearward CoG and perhaps some loss of situational awareness? (ie in a thunderstorm at night, rather than a clear day).


I fully appreciate the economics and the "tombstone imperative", however there are a growing number of the latter and what is clear from this thread is that there are few if any with any clear idea of what happens when a FBW aircraft enters coffin corner and then finds the corner. The sim is no help if its working with duff data. Passing a sim check or even playing with the sim in some rare free sim time is no bloody good if the real thing is different.
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Old 12th Feb 2015, 15:36
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If, in high altitude stall test, for real with a test pilot(s) on board, they cannot get the AOA reduced to recover from the stall there is another option as a very last resort. Just to save the test crew.

Why not have a drone parachute attached to the rear of the fuselage? On deployment, the drag from the chute would certainly lower the nose, by raising the tail to a sufficient degree for recovery and could be cut away when or if it has done it's job.

One would think this has been thought of by much smarter people than I. However upon learning these aircraft haven't been (intentionally) stalled, leave alone deep stalled at high altitude, one can only wonder at the mentality. The uncrashable/unstallable mindset, does give it a way a bit.

Last edited by Sop_Monkey; 13th Feb 2015 at 18:08.
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Old 12th Feb 2015, 15:37
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@captains log - reports due

As far as I can read and understand it ...

When is the actual preliminary report due out? I thought it was late Jan?
Yes it is already out at the end of the 1 month period set out by ICAO ... and sent to ICAO and parties involved ... but certainly not made public ... in spite of the expectation of some pprune posters.

KNKT/NTSC have literally stated (look at previous posts - including a translation of the KNKT interview video) that they 'have the key' to the accident.

KNKT suggested that they would have a press conference later divulging more information. Later that changed to - it would be adressed during an already scheduled annual KNKT report presentation - but it was not (as far as I could see - even digging deep in local Indonesian press reporting).

Most public information is from a parliamentary commission presentation of which fragments can be found on-line.

Due to the fact they were keen(maybe not he best word) to cancel the majority of the salvage operations, surely the investigation team have a clear picture with the aid of FDR/CVR of what happened?


The salvage as such already faltered before they had had time to read the flight recorders. So I find that cause-effect highly unlikely.

If so what's with the delay?

I asked that recently. Nobody knows apparently. And most surprising, nobody appears to be upset about that.

Interesting is that originally KNKT stated they expected the final report in 1 year. Recently statements have reduced that to 8 months.

For an innocent bystander it is quite confusing. The state quite fast that they have 'all' the answers. But will publish quite late ... not having a Prelim ... we have to wait at least 8 months for a Final ... which by definition will have a Public version. It would be nice to get some public KNKT explanation of course.

Last edited by A0283; 12th Feb 2015 at 15:51. Reason: Afterthought - final report statements
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Old 12th Feb 2015, 15:47
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Sims not accurately programmed to train for scenarios that can and do happen in extremis.
I don’t think that’s as important as people make out. The detailed response of an airframe to “edge of the envelope” events in real life is often highly dependant on things like CG, yaw/roll/pitch angles, asymmetry, entry rate, wing loading, air density and many other factors. Every one is different, sometimes remarkably so.

What needs to be trained is:

1. High-altitude stalls are BAD, don’t go there.
2. If you do end up there, it will most likely need control deflections and pitch angles that you’ve never used/seen before to get out of it.

If the sim is up to replicating that, then it’s good enough. We are trying for a generic recovery procedure, not a specific finessed one.
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Old 12th Feb 2015, 16:10
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Test pilots have deliberately test full-stalled various airliners without a bang-seat in the past, so it is something that can be done.
From an interview I saw with an airbus test pilot, he said that they only test a stall close to the edge of the envelope with high energy. The AF447 and air asia stall are far more lethal because the a/c has lost nearly all energy and have the engines at idle. This requires a lot more time to recover the lost energy. Clearly there is a huge difference between a best case stall and a worst case stall. I think it reasonable to want the ejector seat for a Chuck Yeager willing to take an a/c so close to unrecoverable.
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Old 12th Feb 2015, 17:20
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Originally Posted by Sop Monkey
Why not have a recovery parachute attached to the rear of the fuselage?
Don't know. Will it rip the rear pressure bulkhead off, or just pull the tail away when it's unfurled?
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Old 12th Feb 2015, 18:12
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Originally Posted by feedback
Don't know. Will it rip the rear pressure bulkhead off, or just pull the tail away when it's unfurled?
He was only talking about doing this to allow test flights to be carried out safely, so it wouldn't be a problem - the test aircraft's structure would be reinforced as necessary. This method is routinely used for fast jet spin testing (although obviously you do also have the benefit of an ejection seat if things don't work out in those circumstances). An alternative would be something along the lines that Airbus have already used for A400M stall testing, a downward-firing rocket in the tail.

I make no comment on whether any of this is necessary, merely observing that it's readily available and deployed technology within the flight test community.
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Old 13th Feb 2015, 08:02
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Originally Posted by A0283
From that professional viewpoint you can only be very very happy with the approach taken by the Taiwanese ASC. And at the same time negatively surprised by the approach taken by the Indonesian KNKT/NTSC.
Surprised by ASC releasing DFDR readout quickly - yes. Surprised by NTSC - well, not exactly, bearing in mid the outcome of MI185 investigation. Regarding the country of registration and nationality of the captain, stakes are far higher now but DFDR and CVR are read out so evasion will be more difficult.

Originally Posted by A0283
In the AirAsia case the (investigation) authorities have published few preliminary facts (radar, FDR and CVR data). But have published some short ‘final opinion’ conclusions( {we know what happened} “ we have the ‘key‘ “ – and – “it was not a suicide”).

(...)

In the Indonesian case no-one, not a single mention on PPRuNe I think, suggested a suicide.
It is possible that recorders' readouts prompted NTSC to jump the gun.
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