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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 20th Jan 2015, 20:52
  #2261 (permalink)  
 
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"6000fpm is the low 30K's is quite possible in an A320, and does not need an "updraft"."

What would the g loading be at this ROC and would envelope protection not say computer says NO.

Likely cause of such ROC must be exceptionally powerfull updrafts in the storm cell.
The 'g' loading would be 1g (or strictly marginally less by COS(Climb Angle) and marginally more when pitching up).

What envelope protection would intervene? There is no "RoC Protection"? 6000'/m is easily achievable to low altitude, but not usually high up due reduced thrust. All my "scenario" involves is an increasing HW to substitute for the IAS loss. Put another way, the high RoC (increasing PE) is obtained by loss of KE (measured v GSpd) - the key is the increasing HW (temporarily) maintains IAS = AP target.

It does not need to be an updraft.
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Old 20th Jan 2015, 21:04
  #2262 (permalink)  
 
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Supposed Latest
"World News
AirAsia Jet Climbed at Rate Beyond Design of Commercial Planes
Plane Climbed at Rate of More Than 8,000 Feet a Minute, Transport Minister Says"

If this is the latest from Indonesia, it's meaningless nonsense and all we know is that it climbed rapidly and stalled. The ambiguity re instantaneous and average climb rate, and climb speed is obvious (GS or CAS). Any one or a combination of zoom climb, windshear, temperature change, updraft, loss of control, is sufficient to explain a higher than normal rate of climb bleeding into a stall. At the moment any figures remain dubious as we don't have the confirmed source of the figures or confirmation of the readings.
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Old 20th Jan 2015, 21:19
  #2263 (permalink)  
 
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Time

HT to Nigel's few well chosen words that allow me to cut my post by 90%: “...the multitude of warnings is unlikely to immediately improve SA”

A decision chain leading to an accident can be long or very short. The last possible chance to avoid an accident comes between the last two decisions of that chain. If the time available for all decisions or just the last two is seconds, or even virtually instantaneous as some scenarios posted suggest as possible, automation resulting in info and sensory overload probably contributes to an accident. Those are different and relatively rare scenarios compared to when pilots have enough time and automation is helpful.
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Old 20th Jan 2015, 21:25
  #2264 (permalink)  
 
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I wonder whether the " Chimney effect" could be exerted over the top of a rising column of air, say by the ITCZ Jetstream, thereby substantially increasing its upward velocity and power ?
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Old 20th Jan 2015, 21:31
  #2265 (permalink)  
 
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Agreed. As usual, time is of the essence. Even CRM does not always work when there are only a few seconds available to make the decision. It can just impede the advantage of the commander's alleged, superior, experience.

SA in rapid decision making is a vexed question and there are no simple solutions. However computers now do beat humans at chess and lately poker, which has a high and ambiguous SA. The trend is obvious.
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Old 20th Jan 2015, 22:15
  #2266 (permalink)  
 
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Originally Posted by rgbrock1
Is it possible, or even likely, for a severe updraft to carry a commercial airliner to that rate of ascent? Just curious.
It is possible but unlikely. The airplane would have to maintain its pitch attitude, thrust setting, and airspeed, and the gust would have to last long enough for the airplane to attain the vertical speed of the gust. Meteorological analysis of the atmospheric conditions at the time of the accident indicates that upcurrents of this magnitude are unlikely.

Originally Posted by fireflybob
Assuming the data comes from the pressure instruments (IAS/VSI/ALT) these would be indicated values.
The data come from ADS-B messages where they are indicated as “geo”, meaning that the source is GPS. Barometric data were lost at that time.
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Old 20th Jan 2015, 22:29
  #2267 (permalink)  
 
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Any one or a combination of zoom climb, windshear, temperature change, updraft, loss of control, is sufficient to explain a higher than normal rate of climb bleeding into a stall.
You forgot deliberately holding back on the stick, non?
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Old 20th Jan 2015, 22:46
  #2268 (permalink)  
 
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Does that sort of "statistical analysis" inform the decisions in a given company on how much emphasis (and thus resources) to put on above mentioned upset training?
Is there in fact any "statistical analysis"? Which xAA's or airlines require reporting of upset recoveries, do they dump the FDR and CVR for these "near misses" so that the data can be used either in house or by someone centralised for training or even software changes? Australia mandated reporting of stall warning events at least over some years. Do other countries do this?

Is there even a duty to store and share accident related raw data or just the final report? For instance does Airbus have a legal right to the entire unfiltered FDR/CVR data here? Does the BEA (now EASA perhaps) as certifying body?
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Old 20th Jan 2015, 22:59
  #2269 (permalink)  
 
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No aircraft is immune from stalling Finding Nemo. The bus tries to help you not get into that corner of the envelope. Unfortunately a lot of people think that in Normal law the bus is immune to the laws of Physics and Mother Nature
From the FCTM-
High AOA protection enables the PF to pull the sidestick full aft in dangerous situations, and thus consistently achieve the best possible aircraft lift. This action on the sidestick is instinctive, and the high AOA protection minimises the risk of stalls or control loss.
High AOA protection is an aerodynamic protection:
The PF will notice if the normal flight envelope is exceeded for any reason, because the autopitch trim will stop, the aircraft will sink to maintain its current AOA (alpha PROT, strong static stability), and a significant change in aircraft behavior will occur.
If the PF then pulls the sidestick full aft, a maximum AOA (approximately corresponding to CL Max) is commanded. In addition, the speedbrakes will automatically retract, if extended.
OPERATIONAL RECOMMENDATIONS:
When flying at alpha max, the PF can make gentle turns, if necessary.
The PF must not deliberately fly the aircraft in alpha protection, except for brief periods, when maximum maneuvering speed is required.
If alpha protection is inadvertently entered, the PF must exit it as quickly as possible, by easing the sidestick forward to reduce the angle-of-attack, while simultaneously adding power (if alpha floor has not yet been activated, or has been cancelled). If alpha floor has been triggered, it must be cancelled with the instinctive disconnect pushbutton (on either thrust lever), as soon as a safe speed is resumed.
In case of GPWS/SHEAR:
Set the thrust levers to TOGA
Pull the sidestick to full aft (For shear, fly the SRS, until full aft sidestick).
Initially maintain the wings level
This immediately provides maximum lift/maximum thrust/minimum drag. Therefore, CFIT escape maneuvers will be much more efficient.

Last edited by tubby linton; 21st Jan 2015 at 00:32.
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Old 20th Jan 2015, 23:27
  #2270 (permalink)  
 
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@ Finding Nemo

Everything will work just fine if everything works as designed and you stay more or less in the normal flight enveloppe..

Extreme turbulence, or updraft, Sensor failure single or multiple, Sensor icing, single or multiple, autopilot desengage, multiple and conflicting warnings going off, pilots over saturation, and it goes downhill fast.

How many cars bang into each other because they are on cruise control?
How many trucks bang into cars because they are on cruise control?

The sensors => Automatic systems => Human interface => Results do not Always live up to its safety increasing expectations.

The more sensors, the more prone the system becomes to conflicting information and ultimately to desengaging or failure.

PS; IMHO for cars and trucks, cruise control should have been banned a long - long time ago.
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Old 20th Jan 2015, 23:56
  #2271 (permalink)  
 
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Some years ago I was flying an A320 through France ,southbound .
We were riding the core of a very tight jet stream at 330 ,with about 100 kts tailwind , ATC advised turbulence in 20nm so we requested 370 to avoid .
The aircraft was light so no problem . The initial climb at 1500 fpm was ok ,but as we exited the side of the jet into about 50 kts less tailwind the roc increased to 6000 fpm with speed increasing rapidly.
Even with rapid disconnect and gentle handling we zoomed through 390 and topped out at 400 at which point the indicated airspeed fell back rapidly.
We had little time to think about what was going on and traffic and ATC were an issue . Firm but gentle handling got us safely back to 370 .
The event was reported ASR and put down to unusually extreme wind gradient .
not saying this was the case here but perhaps we are not always aware of the potential of a jet upset due to upper air boundaries.

Last edited by zorin; 21st Jan 2015 at 14:12.
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Old 21st Jan 2015, 00:02
  #2272 (permalink)  
ekw
 
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Vilters, the analogy with car cruise control is closer to the mark than you perhaps intend. It leads to complacency. People set cruise control in situations where they should have their foot hovering over the brakes. Of course now there is radar linked braking available in the latest models. For aircraft, pilots who spend most of their time turning knobs on regular short flights on the same route, they too can become complacent. The Colgan Air case is a good example. The best pilots are always thinking about 'what if' scenarios, but fatigue, a domestic dispute, financial stress, alcohol and a ton of other things can leave any person with dulled responses. This is always a hidden factor with mistakes. It is also why HAL needs to be given more responsibility, not less. The sensors on the human will fail before HAL loses all SA. AF447 may have had frozen pitot tubes but it was the human that commanded the THS to its stop.
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Old 21st Jan 2015, 00:23
  #2273 (permalink)  
 
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Attention

ekw...Are there not studies showing it is also more difficult to maintain the same degree of vigilance and attentiveness when overseeing an automated system compared to constant manual control, difficulty being a slightly different metric than outside stresses?
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Old 21st Jan 2015, 00:33
  #2274 (permalink)  
 
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ekw makes some fine points , which is why pilots should be well paid and not have to have second income sources and take care of all problems including rest before flight, honorable retirement and health care and have nothing but flying the plane on their mind.
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Old 21st Jan 2015, 00:43
  #2275 (permalink)  
 
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Originally Posted by Leightman 957 View Post
ekw...Are there not studies showing it is also more difficult to maintain the same degree of vigilance and attentiveness when overseeing an automated system compared to constant manual control, difficulty being a slightly different metric than outside stresses?
Indeed there are - from more than a century ago in 1908 two psychologists Yerkes and Dodson developed a 'law' called after them but often refereed to as the inverted U.

If someone is idle with almost no stress, their attention level drops to its lowest level, if someone is extremely busy with high stress the attention level drops - sometimes called attentional or cognitive tunneling (tunnel vision). The ideal is a medium level stress that keeps the mind stimulated but not over worked.

See Yerkes?Dodson law - Wikipedia, the free encyclopedia and numerous other references.
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Old 21st Jan 2015, 00:52
  #2276 (permalink)  
 
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Just a reminder that high alt windshear and jet streams are not usually found in the ITCZ region. Nor is hail. The most probable w/x related upset is violent convective turbulence and heavy rain. Microbursts are common but at lower altitudes. CBs are just plain dangerous in the ITCZ.

Last edited by RifRaf3; 21st Jan 2015 at 03:03.
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Old 21st Jan 2015, 01:08
  #2277 (permalink)  
 
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Studies

IanW: Indeed there are...... Yerkes and Dodson developed ...the inverted U.

My point is also asking whether a person overseeing an automated system has "farther to go" to catch up specifically in the case of very rapidly changing events. In all but rare cases this wouldn't matter because time available allows it, as low accident rates show. But in a very rapidly developing situation is there a response time penalty for all pilots flying in an overseer role compared to a hand flying role? If so at what point does that time penalty become long enough that success or failure is determined by it? Another way to put it would be to ask at what point the rapidity of events cascades to apparently become insurmountable in the "success" time available, comparing overseer and hand piloting roles. I think a lot of people would attest that there is a rhythm to flying, where one is physically as well as mentally engaged.
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Old 21st Jan 2015, 03:19
  #2278 (permalink)  
 
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rifraf3

you make some fine points. I think THEY hit an energy enhancing event (ie updraft etc). the plane reacted by trying to hold altitude, OVERSPED, then pulled up, trimmed up, THEN GAVE UP

and the pilots suddenly were in alternate 2 or direct law and forgot to manually trim nose down

stall, fall, bye bye you all.
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Old 21st Jan 2015, 04:47
  #2279 (permalink)  
 
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They really need to recover the horizontal stab jackscrew.

.
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Old 21st Jan 2015, 05:18
  #2280 (permalink)  
 
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Could the loss of Radom be the cause of sudden NU attitude ? We lost once a MD-82 (conic) tail cone at landing after a seemingly unverified and wrong exercise from cabin crews, and the Captain/PF was used to land very NU...?

Thank you Machinbird for the flat spin theory : waiting the FDR report unpatient :-)
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