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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 9th Feb 2015, 01:05
  #3121 (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
  #3122 (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 laser level.

Last edited by xcitation; 9th Feb 2015 at 20:00.
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Old 9th Feb 2015, 06:06
  #3123 (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 laser 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
  #3124 (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
  #3125 (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 l@ser 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
  #3126 (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
  #3127 (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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Old 9th Feb 2015, 12:33
  #3128 (permalink)  
 
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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.
ASRAAM answers the point I have been trying to make... Alternate Law is, by definition, a Reversionary Mode. It is Reversionary for a good reason, and hence why Stall Protection is degraded.

If the system integrity in Alternate Law was high enough to justify stick pushing, then it would be called Normal Law

Look at the latest OEB - the effects of a "Stick Pusher" in Normal Law A320 uncontrollably diving to 4000'/m. If there are hidden flaws in Normal Law, how could you write a Safety Case for such a Pusher in Alternate Law?
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Old 9th Feb 2015, 12:50
  #3129 (permalink)  
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What a contrast.

One thread intent on denigrating automation in the cockpit, and another bashing the humans who (possibly) shut down the wrong engine.

In either case a flyable Aircraft has crashed. - I don't know how my computer works, but I can operate it until it goes wrong. Where's the weak link?
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Old 9th Feb 2015, 13:45
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<<<I don't know how my computer works, but I can operate it until it goes wrong. Where's the weak link?>>>

I do know how my pencil works and I can balance my checkbook without problem.

Where is the weak link?

IT IS SIMPLE, the weak pilot is the weak link. The pilot must be able to do it all, until the plane is safely on the ground.

Automation can reduce stress and strain in normal ops and assist in emergency ops. This will reduce the need for rest after the flight. BUT a pilot who takes his plane to MAA (max authorized altitude) and can't hand fly it there is fooling himself!
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Old 9th Feb 2015, 13:53
  #3131 (permalink)  
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skyhigh:

BUT a pilot who takes his plane to MAA (max authorized altitude) and can't hand fly it there is fooling himself!
Can you elaborate a bit on that one?
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Old 9th Feb 2015, 14:08
  #3132 (permalink)  
 
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elaboration


for aterpster:


What I am trying to get at is the ability of some pilots to command their autopilot to climb to the maximum authorized altitude of the plane (service ceiling so the ancients like me liked to say) and would be unable to hand fly the plane at that altitude.

So too, taking your plane into any condition that required the use of autopilot and could not be flown ''by hand''.

to be sure, if regulations require the autopilot to be used (rvsm or Catii apch) you use the autopilot, but you must be able to actually hand fly the plane there in case the autopilot quits.
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Old 9th Feb 2015, 14:16
  #3133 (permalink)  
 
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I think he means no pilot should depend on an autopilot so much that if it fails he cannot safely continue operating the aircraft manually from where the autopilot failed. MAA for autopilot operation should never be higher than where he can properly hand fly. I agree.
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Old 9th Feb 2015, 14:27
  #3134 (permalink)  
 
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Does no-one habitually cruising at Max rather than Optimum ever contemplate the possible ramifications of a TCAS RA ?
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Old 9th Feb 2015, 14:39
  #3135 (permalink)  
 
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I had the habit of showing FOīs the yoke movement in the Boeing while at high altitude, autopilot ON. The inputs are minimum, over-controlling is common until they finally get the sense of the relationship of thin air /speed and angle of attack. Canīt do that on the bus.
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Old 9th Feb 2015, 15:47
  #3136 (permalink)  
 
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Pilot confidence

Bubbers at 3156: "I think he means no pilot should depend on an autopilot so much that if it fails he cannot safely continue operating the aircraft manually from where the autopilot failed. MAA for autopilot operation should never be higher than where he can properly hand fly."

There have been a lot of posts to date saying more training is needed. Here are some pointed questions that in 158 pages into 8501 I don't think have yet been asked or answered: Are some current A320 pilots posting on this list suggesting that they personally know other A320 pilots whose skill they consider to be questionable or insufficient to hand fly the AC over any assigned route and altitude? More specifically, would A320 pilots posting here claim they would be comfortable as passengers with any other pilot in their system flying alone in the cockpit at altitude transiting the ITCZ and facing a storm front at night? Are the same airline operators that are hoping to convince the public of transparency and system capability also at the same time not ensuring by sim and actual practice and regular check rides that in the event of control system failure their pilots are capable of flying the aircraft?

I can understand that no one who has reservations would want to state them publicly. However pilots who have full confidence in all other pilots they know should have no hesitation expressing confidence.
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Old 9th Feb 2015, 16:13
  #3137 (permalink)  
 
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Carbon

Did you have passengers on board?

"showing" colleagues new things at the edge of the envelope is not a good idea unless its a properly planned training flight
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Old 9th Feb 2015, 16:29
  #3138 (permalink)  
 
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Sim training is the answer

There seems to be so much discussion in this thread about stall recovery techniques that I wonder if there are many out there who don't understand the problem and wouldn't know what to do - some of them Bus drivers. Stall recovery training on the "unstallable" Airbus was like the lifeboats on the "unsinkable" Titanic, not deemed very important. Airline training has concentrated on recovery from an approach to a stall at low level. This is a very different from the situation of the aircraft being in a fully developed stall at high altitude where the recovery technique is quite different. Now that four Airbus aircraft have been lost to stall events (two on test flights), it's clear that crews need to be better trained in case they do experience such a rare event. This needs classroom and simulator training even if the fidelity of the sim is not 100% - it's the drill that counts.

As for the Bus not giving the pilot full control, Bonin had full control available and could have saved his aircraft if he'd used it correctly. He didn't realise the predicament he got into - a full stall - by mishandling the aircraft (in Alternate Law 2, at very high altitude, in turbulence, at night, fatigued, frightened and inexperienced) and didn't know what to do to recover. Neither did his more experienced crew member.

It doesn't help that the Bus doesn't have stick shaker or pusher, so all the more reason to be trained to recognise a proper stall and not to ignore a stall warning unless absolutely sure it is false.

There is a very good YouTube video on Airbus Stall Training.

Yes, the Trident had a pusher. It had to have one because the "T" tail made it liable to get into a deep stall from which there was no recovery! Sadly, on one occasion where it might have helped the crew, it was overridden (presumed false ?) and the aircraft crashed.
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Old 9th Feb 2015, 16:44
  #3139 (permalink)  
 
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Originally Posted by Heathrow Harry
Carbon

Did you have passengers on board?

"showing" colleagues new things at the edge of the envelope is not a good idea unless its a properly planned training flight
Harry,
Carbon made the distinct point that the aircraft was flying on autopilot all the time. What was being shown was how small the yoke movements were by the autopilot. Carbon pointed out that in the 'bus this would not be possible due to the side-sticks and stationary throttles
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Old 9th Feb 2015, 16:48
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fatigued, frightened and inexperienced)
Fatigued frightened yes. Inexperienced well there are quite a few captains flying around with a lot less hours even in Europe. Something is going fundamentally wrong with training departments. IMHO the authorities have caused training departments to become checking departments. This is because more is asked on an OPC LPC & the airlines do not want to pay for more training time.
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