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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 1st Jan 2015, 08:11
  #821 (permalink)  
 
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From an article online in the Sydney morning herald.


Mr Soejatman said the plane was equipped with a Mode S radar, a relatively new piece of equipment which sends more comprehensive information, in real time, from aircraft to ground.

Leaked figures show the plane climbed at a virtually unprecedented rate of 6000 to 9000 feet per minute, and "you can't do that at altitude in an Airbus 320 with pilot action".

The most that could normally be expected would be 1000 to 1500 feet on a sustained basis, with up to 3000 feet in a burst, he said.

The plane then fell at an even more incredible rate: 11,000 feet per minute with bursts of up to 24,000 feet per minute.

He said the Air France A330 Airbus that crashed in 2009 killing 228 passengers also reached dizzying ascent and descent rates, but some of the figures cited by Mr Soejatman are higher.

"We can't rule out that the data is wrong," he said, but added that they came from the aircraft itself, transmitted over the Mode S radar.
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Old 1st Jan 2015, 08:16
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He who reports Mode S radar as a relatively new piece of equipment can not be taken serious.
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Old 1st Jan 2015, 08:38
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@ bille1319 & dragon man

Thanks, guys! What I've been searching for through, lo, these 800+ posts.

I'll take the leaked climb rates with a grain of salt. But my suspicion is this crew simply inadvertently penetrated the updraft core of a CB and got tossed out of control. Possibly with some airframe damage (not necessarily a full "in-flight breakup") to exacerbate the LOC.

Why and how they got into that situation will have to wait for the CVR, to find out what they could see out the windows (if anything) and what they could see on the scope (if anything). Along with the other details between "A" and "Z" that we don't know yet.
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Old 1st Jan 2015, 08:45
  #824 (permalink)  
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Not only that it he does not know how a mode S transponder works as well . The altitude is derived from barometric pressure = Also subject to outside pressure variations .if the values transmitted down by the extended squitter are exsessive and short burst they are unlikely to be real . In other words it is not because you have huge burst of altitudes that you can deduct vertical rates and that the actual aircraft went there . They are just coded alt bursts and that why in ATC we filter them out .
Not saying that is what we have here but it surely looks like it to me .( unless of course the values are increasing over time and the responses sequence , I have not seen them )
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Old 1st Jan 2015, 09:30
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CAN YOU IMAGINE how dependent we have become on computers to do things, and THUS when a NUTTY value comes along the COMPUTER BELIEVES IT AND THEN GIVES UP
NUTTY, as in having a stall warning system that doesn't work when measured airspeed is below 60kts:

If the CAS measurements for the three ADR are lower than 60 kt, the angle of attack values of the three ADR are invalid and the stall warning is then inoperative.
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Old 1st Jan 2015, 09:45
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Roseland, spot on!!

You could add to your post the the ingrained trained response to the low speed scenario is to push the nose down, but now in this system once the pitot block or AOA error is cleared the combined aircaft systems decide thats its now above 60kts and presents "STALL, STALL, STALL".

A totally opposite expectation of action/result.

Analagous to someone reversing the piano keys from high to low on a concert pianist just before the big show - her/his thousands of hours of practice have just gone out the window and now mean diddley squat.

Someone is culpably negligent in such a design flaw.
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Old 1st Jan 2015, 10:00
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As if the "computer giving up" isn't an implicit assumption from the design team that the pilot will know better to do at that point.
or an implicit assumption that the design team simply don't know what to do at that point.
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Old 1st Jan 2015, 10:02
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Mr mach 5.5 (?) I think they mean when airborne. Weight on wheels disables it anyway.

Last edited by CaptainEmad; 1st Jan 2015 at 10:03. Reason: M5.50
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Old 1st Jan 2015, 10:10
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Makes perfect sense. I don't want to taxi to the active with the stall warning bleeping at me because the wind is playing with the sensors.
That's why every other aircraft company I'm aware of use squat (weight on wheels) switches.

For much of AF447's descent, the stall warning was inactive either because the pitots were iced, or because the airspeed really was that low. When the PF pushed the stick forward and the speed rose above 60kt the stall warning sounded.
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Old 1st Jan 2015, 10:29
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YET AGAIN - Why Not?......

I recall, after MX370 disappeared last year, posting a plea for aircraft manufacturers to install a simple water-pressure or salt water-activated device in the upper part of the tail in ETOPS flight aircraft, which could release a simple floating locator beacon powered by a solar battery. Even allowing for currents and wind movement at least the SAR people would know where to start looking. It would now seem that this plea should not be limited to ETOPS aircraft.
Yet again this simple and relatively cheap device would have enabled the Air Asia aircraft to be located almost immediately and spare the distress of relatives awaiting news of their loved ones.
Even allowing for R&D costs it must be worth the expense. Come on all the DGCAs and CAAs of the world. Get a grip on this. Forget satellite interpretations of ACARS transmitted postions and other complicated systems, insist on something simple. The technology is there. Do something about it.
For reasons best known to the Prune moderators my previous post was removed after a few hours. Should I assume that this one will disppear too?
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Old 1st Jan 2015, 10:38
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I think the mods probably think this has been done to death. Ian W provided several factual posts along the lines that adequate technology is available but it is up to the operators to implement, a situation which it seems is about to be tightened.
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Old 1st Jan 2015, 10:49
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If the CAS measurements for the three ADR are lower than 60 kt, the angle of attack values of the three ADR are invalid and the stall warning is then inoperative.
Roseland, spot on!!
....
Someone is culpably negligent in such a design flaw.
At what speed, and how derived, do you suggest the STALL warning is enabled/disabled? At low speed, "how" do you proipose to measure AoA in order to drive the "STALL" warning?

I note Roseland omits the explanation for the 60K cutoff:
This results from a logic stating that the airflow must be sufficient to ensure a valid measurement by the angle of attack sensors, especially to prevent spurious warnings on the ground.
Do we really want the STALL warning shouting at us until mid takeoff run??

Airbus' and other modern aircraft are clever, but they cannot rewrite the laws of physics. Even my little homebuilt aeroplane has a speed based "cutoff" for AoA (Stall) warnings.


PS I do not see WoW as a "better" solution, since the LGCIUs sense that, and fail relatively frequently, and MEL permits dispatch with 1 U/S. Do we really want to disable STALL watning for simple LGCIU problems?
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Old 1st Jan 2015, 11:17
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PS I do not see WoW as a "better" solution, since the LGCIUs sense that, and fail relatively frequently, and MEL permits dispatch with 1 U/S. Do we really want to disable STALL watning for simple LGCIU problems?
We'll have to disagree. I think having stall warning disabled by low IAS (frozen pitots?) is a significant weakness.

What do others think?
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Old 1st Jan 2015, 11:18
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I agree 60 Plus, they need something in place for aircraft going down in deep oceans, submarines have been using similar technology for a long time, something has to be done, because what we have in place is not working, the money they spend and still keep spending on these searches is crazy.

Someone needs to show leadership soon and get the existing technology working or bring other technologies online, this can't go on like it is. They have had so many warnings, they need to act and fix all these issues.
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Old 1st Jan 2015, 11:19
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How about enabling it if at 30k ft and in alternate law
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Old 1st Jan 2015, 11:22
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A few words on critical computer systems and automation from someone involved with regulated medical software, where a fatal outcome is an assumed possibility.

Systems and software are really not intelligent per se. In every system there is a perceived risk, designing complex inherently safe solutions is simply not possibly. That is why designs in general are approach with an obligatory risk assessment for every main functionality or mode.

The simplest formula to categorize risk is LIKELYHOOD x SEVERITY = CALCULATED RISK. Every single risk assessment then contains a mitigation or solution. It can be a required new feature or system, it can be training or in a perceived low risk simply acknowledge the risk, or try to lower the severity.

A long story short, icing of pitot tubes, pilot errors, system crashes, etc., etc. are (should be) all accounted for in design. No-one assumes to design an inherently safe machine, where a fatal outcome is even a remote possibility. The sad part: the only intelligence in design is learning from mistakes, testing, and yes, learning from real-life accidents.
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Old 1st Jan 2015, 11:22
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Perhaps if the audible portion of the stall warning could be attenuated below 60 kts that would be sufficient? There would be an added benefit of giving the PF something to differentiate between a classic stall and the rarer event of being under 60kts IAS.
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Old 1st Jan 2015, 11:41
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Stall warn inhibit

NigelOnDraft

You say you don’t like WoW as an inhibit for the stall warning because LGCIUs fail relatively frequently.

You will, no doubt, recall the wingstrike at Hamburg (A320, 1st May 2008). The aircraft thought it was on the ground (the LH LGCIU detected WoW) and it switched to ground mode. Even though both pilots had full right stick it wasn’t enough to stop the wingstrike because in ground mode roll control is halved.

What are the implications of a faulty LGCIU triggering ground mode in flight?

Last edited by Roseland; 1st Jan 2015 at 11:51.
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Old 1st Jan 2015, 11:44
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NoD and Roseland both make persuasive arguments. I do think this is an issue that wasn't given sufficient weight in the AF447 report.

Granted, the crew in that incident had up six ways from Sunday before the incident got that far; I grant you that without reservation.

I don't know which of you is right. I do know I'm still boggled at the existence of a system that, when things have gone to excrement in every conceivable way, gives you a stall warning when you push forward, and stops the stall warning when you pull back.

You can engineer as many different control laws as you like; Murphy's will trump them all eventually. I do believe the clever chaps and chapesses at AB never envisaged this one, and who can truly blame them?
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Old 1st Jan 2015, 11:50
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Originally Posted by Roseland
What do others think?
You noticed that no one jumped on it?

Maybe this is because things are anyway strongly amiss when an airliner troddles along at 60kts? And the point of possible/probable recovery will have been long passed at that stage.
Maybe it would be more important to work on preventing getting down to para glider speeds in the heavy iron in the first place...
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