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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 8th Feb 2015, 10:39
  #3101 (permalink)  
 
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Originally Posted by auraflyer View Post
I was just putting the logical result of Ian W's suggestion into words as it is an interesting idea and I try to keep an open mind -- but I don't think the solution is more automation, hence why I put "controversially" and why I ended how I did.

I won't get into a fight, since you drive A320s and I don't, but AFAIK existing stick pusher logic includes an altitude minimum (e.g. Q400 only activates > 200 feet AGL), so there's no reason you would not implement equivalent logic *if* you were to do this.
I am glad to see that my suggestion triggered some discussion. If I were looking to design something along those lines I would expect to use AOA and probably a variable delay dependent on flight phase. A parameterized delay would prevent spurious warnings triggering trim changes. Although I note from other events that spurious warnings seem to trigger zoom climb in alternate law.
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Old 8th Feb 2015, 10:46
  #3102 (permalink)  
 
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Stick pushers bla bla bla

The big picture is these complex machines are designed to be operated by appropriately recruited, educated, trained, current and competent crews who adhere to SOP's, FCOM, Air Nav regs etc etc etc

No amount of anything will safe guard the aircraft and innocent passengers from alleged utter stupidity.
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Old 8th Feb 2015, 12:08
  #3103 (permalink)  
 
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Originally Posted by henry crun
Collectively they could report a dangerous rate of descent. Differentially they could detect inappropriate attitudes.
More often than not the stall results from an inappropriate rate of climb, and the attitudes can be quite normal.
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Old 8th Feb 2015, 12:18
  #3104 (permalink)  
 
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Isn't the real story here that airlines / manufacturers want to fully automate flight. Pilots and crew are seen as expensive.

And so Airbus has tried to start that process. It couldn't go all the way fully-automated because there would be huge resistance from passengers / crew / regulators, but it has implemented a beginning.

The Airbus system comes with a manual of how to use it, makes it sound so easy ... however if something goes wrong it is unclear how to resolve the situation because the system's many secrets are not made available and in an emergency you have seconds to understand what's going on under the hood.

Airbus does not want pilots to be able to switch the system off at will, because that would derail the business plan of full automation.

For the bean counters, it's just money. Lives lost though regrettable are just a matter of insurance.

Automation seems the trajectory of the economy ... unless something changes. And we are now in an intermediate phase were there is an inevitable dishonesty about what is occurring, because automation is being phased in semi-covertly.

If the pilots / crew make a fuss, or passengers / airlines are scared ... then it will slow things down. If new plane technologies come through that require pilots, it will slow things down. If pilots were seen once again as part of the experience, it will slow things down. If the world gets richer suddenly it will slow things down.
Some operators have expressed an interest in 'full automation' - but only because they have absolutely no appreciation of the end-to-end costs involved.

If they think pilots are expensive, wait till they see what a theoretical 'unmanned' airliner would cost to design, build, certify and operate.

Not only that, achieving the required level of safety for a passenger-carrying operation simply isn't technically feasible - and won't be in any of our lifetimes - if at all.
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Old 8th Feb 2015, 12:28
  #3105 (permalink)  
 
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... in conversation with Leightman 957 it occurred to me (& maybe L957 too) that
stalling in general and higher altitude stalls particularly have been given much less
attention than those at low (more immediately threatening) altitude by safety authorities
and in liine training ?
... over a significant span of recent airliner development.
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Old 8th Feb 2015, 12:38
  #3106 (permalink)  
 
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I believe 14,000 ft is the highest that any manufacturer flight-tests stall characteristics nowadays.

Couple that with the low-speed limitations of Computational Fluid Dynamics, and we have a whole flight regime for which wide-ranging reliable data doesn't appear to exist.
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Old 8th Feb 2015, 13:00
  #3107 (permalink)  
 
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Isn't the real story here that airlines / manufacturers want to fully automate flight
And plenty of posters on here seem to agree e.g. adding technology to solve every problem?

The Airbus system comes with a manual of how to use it, makes it sound so easy ... however if something goes wrong it is unclear how to resolve the situation because the system's many secrets are not made available and in an emergency you have seconds to understand what's going on under the hood
I would disagree with the underlined statements:
A: I do not believe it "unclear" how to resolve situations, but people have either failed to follow the manual / their training, or they have done something completely unpredictable.
B: It is not essential, IMO, to (completely) "understand" what is going on under the hood. Not even what law the aircraft is in. Yes - a level of knowledge is required, and will help in exceptional circumstances. But if you fly the aircraft sensibly, remember it is still an aircraft and not a computer, and apply basic flying skills, then the finer points of FBW are (as designed) usually invisible to you.

Automation seems the trajectory of the economy ... unless something changes. And we are now in an intermediate phase were there is an inevitable dishonesty about what is occurring, because automation is being phased in semi-covertly.
I do agree with the basics of this - initially the benefits of FBW showed up as "protections" prevented some accidents (albeit there was also a learning curve), but there was still basic airmanship and flying skills about.

Now we have a new influx of pilots, who only know FBW, rarely handle the aircraft, the industry relies on the automation. When the automation lets them down, they have nothing to fall back on. Even the older generation pilots have been "deskilled" as well.
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Old 8th Feb 2015, 14:27
  #3108 (permalink)  
 
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GPS on corners

Isn't this used on some fighters to sense attitude? Phase lock, phase differences? Maybe on the mil band only?
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Old 8th Feb 2015, 14:59
  #3109 (permalink)  
 
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I would have thought the logic behind stopping the aural stall WARNING when aoa becomes untrustworthy makes sense EXCEPT when an approach to stall has just been sensed. If the warning is blaring away seems more prudent to let it continue. Think the software is missing a IF....THEN branch on this one. Also, if high THS is a very unusual state for normal ops, is there a warning to draw attention to it?
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Old 8th Feb 2015, 15:41
  #3110 (permalink)  
 
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Inquisitor

..out of the profession for many years now but don't necessarily
agree CFD is limited to low speed aerodynamics or altitudes.
no doubt even faster computerd are required and different
mesh/models but think it is a very advanced technology now.

..unless you know different.
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Old 8th Feb 2015, 17:22
  #3111 (permalink)  
 
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HarryMann,

Not sure, as I have no expertise in the field myself. I was referring to what somebody far cleverer than I told me when visiting a wind tunnel test facility. He seemed to be saying that in the low-speed, high-alpha regime particularly, there were simply too many variables to produce a solid deterministic model, as opposed to computers running out of steam.

Apparently they have it pretty much nailed for high-speed stuff, though.
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Old 8th Feb 2015, 22:36
  #3112 (permalink)  
 
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Inquisitor

Sorry I misread...

However I know a bit more about that regime and disagree still

separated flow is complex and agree demands lots of computing power

it's a matter of filling in the gaps with real w/t models studies.

I doubt there's a lot not known.

I don't believe these are the issues here:

isn't this about the cockpit, training, operational procedures human
response etc,

Last edited by HarryMann; 8th Feb 2015 at 22:48.
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Old 8th Feb 2015, 23:19
  #3113 (permalink)  
 
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It's about a lot of things in my mind HM.

I currently work in the unmanned arena, and am desperately fighting those who think that more computers and more automation is the answer to everything.

My own view is that that we have simply replaced one failure mode with another.

it's a matter of filling in the gaps with real w/t models studies.
I'd be interested to know what's out there in terms of real-world collected data, particularly wrt high-alt, high-mach, high-alpha, low-IAS scenarios? My current belief is that a wide dataset here is absent, save for that collected from real-world accidents?

Last edited by TheInquisitor; 8th Feb 2015 at 23:42.
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Old 9th Feb 2015, 01:05
  #3114 (permalink)  
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TheInquistor;
I'd be interested to know what's out there in terms of real-world collected data, particularly wrt high-alt, high-mach, high-alpha, low-IAS scenarios? My current belief is that a wide dataset here is absent, save for that collected from real-world accidents?
For those carriers doing FOQA/FDM from engine-start to engine-stop and who retain their deidentified data for some period of time, there is a wealth of information for the period and for the "events" you specify.

Sharing such data is another matter. A number of projects have attempted to do this but so far nothing has emerged as a distributed archive of common types. How data is handled, confidentiality, legal implications and legitimate concerns as to data-use impede data sharing. But it's out there.
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Old 9th Feb 2015, 02:09
  #3115 (permalink)  
 
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@Henry crun
Not a pilot, just an avionics guy, so tell me to go away if you wish.

I would suggest the use of totally separate, lane segregated, battery powered gps at the four corners of the airplane. Collectively they could report a dangerous rate of descent. Differentially they could detect inappropriate attitudes.

Gps accuracy is not good in airplane control terms, but it is definitely accurate enough to sense outrageous errors.

Why not?
Interesting idea.
In fact GPS is amazingly accurate when used differentially to calculate attitude down to sub mm accuracy. The timing pulses in the GPS satellite data packets are used to generate relative attitude information instead of the spacial reference data. This has been demonstrated successfully in many small civilian aviation devices.
The problem here is that the wings have tremendous flex especially at the ends. Even the fuselage has a significant movement at the ends. This would have to be compensated for - maybe with [email protected] level.

Last edited by xcitation; 9th Feb 2015 at 20:00.
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Old 9th Feb 2015, 06:06
  #3116 (permalink)  
 
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What is new here ?

What do you think you would be gaining that you don't already have from the INS's ?

Why is this gps attitude capability seen by some as a new fix ?

The existing 3-axis ring [email protected] gyros already pump out all the spatial data you could ever need, with all rates included.
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Old 9th Feb 2015, 10:18
  #3117 (permalink)  
 
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Banjo

Stick pushers bla bla bla

The big picture is these complex machines are designed to be operated by appropriately recruited, educated, trained, current and competent crews

The point is that when an Airbus goes into alternate law, it has less stall warning and alleviation devices than a 1960s Trident. That is not an advancement in safety.

I expect that when the AB was designed, it was not expected that so many aircraft would degrade from normal law to alternate law. But here we are, yet again. It would seem clear that the degraded systems need a stick-shaker/pusher to back up the aural warnings (or a thrust reducer, to lower the nose).

As to Nigel, who says a pusher or thrust reducer would not be good on take off ( ), this never stopped the Trident having pushers, and not having any problems with them. Besides, AB could easily limit the action to greater than 2,000 ft. And as far as I can see, this would not add weight or cost to a standard AB. I am sure that both stick push and thrust reductions, for approaching the stall in alternate law, could be made as a simple software change.
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Old 9th Feb 2015, 10:52
  #3118 (permalink)  
 
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What is new here ?

What do you think you would be gaining that you don't already have from the INS's ?

Why is this gps attitude capability seen by some as a new fix ?

The existing 3-axis ring [email protected] gyros already pump out all the spatial data you could ever need, with all rates included.
Absolutely! What accident are you trying to prevent by suggesting sticking GPS's all over the ship? All these accidents had perfectly functional attitude indicators right in front of the noses of the pilots.

It was obvious in the case of AF that neither pilot took any notice of their attitude indicators. Attitude is everything - something that is trained from the first minute of basic IFR training.

If that is being de-trainined in Airbus types then that is the heart of the problem. Forget the more/less automation arguments - if you are hand flying an aircraft, your eyes are on the attitude indicator, with a brief and frequent scan to other instruments such as airspeed and altitude. If you are monitoring an autopilot, not much changes.

In the case of air data problems such as unreliable airspeed including simultaneous stall/overspeed warnings, you are not distracted by the warnings, you simply change your scan from attitude/airspeed/altitude to attitude/thrust until it's sorted.

It just ain't that hard.
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Old 9th Feb 2015, 11:24
  #3119 (permalink)  
 
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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Silverstrata,

Exactly HOW does your stick pusher know it is approaching the stall, perhaps it will use the AOA probes. Perhaps it was the ice on the AOA probes that generated the reversionary mode in the first place. Or perhaps it will take it's info from a failed sensor and just push anyway.
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Old 9th Feb 2015, 11:41
  #3120 (permalink)  
 
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In fact GPS is amazingly accurate when used diferentially to calculate attitude down to sub mm accuracy
That's not actually true in most circumstances. There have been experiments with highly specialised GPS receivers tracking L2 Phase for aircraft attitude purposes that worked well, however general GPS is simply not good enough.

Modern drones have experimented with thermal horizon detectors which work quite well in flat terrain, but have problems in hilly terrain.

The current alternative to INS is a combination of GPS and 3D accelerometers / rotation sensors that provide quite accurate attitude and location information. They do not meet full INS accuracy but at under $100 a sensor unit they are extremely good value.
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