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Author Topic: Are aircraft "overautomated"?  (Read 12689 times)

Offline SeanB

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Are aircraft "overautomated"?
« Reply #25 on: 09/08/2011 18:15:25 »
Most stalls occur in the region in which recovery is impossible - right near the ground, generally with some bad outcomes. Mostly too slow, to low and too little power. Most dangerous part of flying is take off and landing, and the part in between is generally pretty quiet, may be a little turbulent, but weather is worse nearer the ground and nearer the top of the flight envelope.

The AF plane was unfortunately operating at the edge, and the accident pushed it into a region that was supposed to never be entered as being a known danger. A combination of poor route selection and a known flaw in the plane design, which in the end resulted in the crash.
 

Offline Geezer

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Are aircraft "overautomated"?
« Reply #26 on: 09/08/2011 19:47:21 »

Where did you see that simulators can't emulate a stall?


I thought it was on that site, but I can't find now it either! I'll try to retrace my steps and dig it up. I was quite surprised when I read it too.

I'm pretty sure it's easy enough to simulate the stall. I got the impression that what was lacking was the simulators' ability to handle the recovery accurately.
 

Offline Geezer

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Are aircraft "overautomated"?
« Reply #27 on: 09/08/2011 20:03:38 »
Quote
Seems to suggest a "well, we know that's never going to happen" mindset.

Well, maybe.

To do live training they'd presumably have to genuinely stall a genuine plane. Probably repeatedly. The risk of accidental stalling is clearly a real one, and a stall of a loaded passanger plane which leads to a crash will likely lead to the death of several hundred people... but that doesn't necessarily mean that live training is the right thing to do.

If stalls in modern, highly automated planes are very rare, if for example there is a reasonable expectation that most pilots wouldn't encounter a stall in their career otherwise (and I have no idea what the stats are, but it must be something for which stats exist), more live training would not necessarily be expected to save more lives in the long run.. because if stall training killed a significant number of crews that would add up! (Leaving aside the fact that if pilots dropped several planes out of the sky in training, it might obviate the need for training entirely.. because it would put the public right off those models, I'd think!)

There does not seem to be much real stall training at all. I see some people are suggesting that there ought to at least be live training in trainer aircraft. (I can understand why the airlines would not be too keen to run the risk of pranging one of their nice aircraft.)

Is it true that an airliner at cruising altitude has to operate within a narrow window of parameters to avoid stalling?
 

Offline Geezer

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Are aircraft "overautomated"?
« Reply #28 on: 09/08/2011 23:43:43 »

Where did you see that simulators can't emulate a stall?


I thought it was on that site, but I can't find now it either! I'll try to retrace my steps and dig it up. I was quite surprised when I read it too.

I'm pretty sure it's easy enough to simulate the stall. I got the impression that what was lacking was the simulators' ability to handle the recovery accurately.

This is it, but it's not very clear how new the technology actually is.

"That’s because pilots are supposed to never allow a plane to reach a stall in the first place, and because earlier-generation simulators were not able to mimic a full stall.

But thanks to new simulator technology, “now you can put someone in a stall scenario and let them recover,” Babbitt said."

http://uprta.org/faa-to-seek-major-changes-in-pilot-training/

 

Offline Geezer

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Are aircraft "overautomated"?
« Reply #29 on: 10/08/2011 01:15:04 »
Sorry if I'm becoming a bit obsessed with this one!

If I remember correctly, accurate airspeed data becomes more critical at greater altitudes (because of reduced air density). That being the case, there should be no circumstances under which the automatic systems, or the crew, ever get suspect airspeed data.

Why don't they calculate it based on what the engines are doing? Would it not be possible to estimate airspeed from air density, turbine speeds and fuel consumption, or maybe they already do that?
 

Offline graham.d

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Are aircraft "overautomated"?
« Reply #30 on: 10/08/2011 08:57:21 »
The manual recommends (as I guessed at) using GPS data to get, at least, ground speed. The only problem with this is that at high altitude there can be a large difference between airspeed and ground speed because of the very high winds that can be encountered. In any case, if the stall warnings are going off then it is perfectly possible to increase the thrust and use the artificial horizon instruments to level the craft and to restore a safe flying attitude. It seems like the pilot did not believe the aircraft was in a stall but in a dive. It is a very fundamental error in any aircraft to believe your senses rather than the instruments. It is very basic training in light aircraft to NOT depend on your senses when recovering from a spin, for example, especially in low visibility situations.

Rosy, every pilot would have had some live training on a stall recovery in some aircraft though maybe not in every aircraft he is expected to fly. It should have been done in a simulator though but it looks like the early simulators did not cover this fully (from Geezer's post), which is very surprising, though the omission seems to have been corrected now. Every pilot should be aware of what to do in a stall though. It does look like a case of insufficient practice; the stall would have put the aircraft into an intermediate mode (alternate law, as opposed to normal law and direct law) between fully automatic and manual modes, as the feeds from the airspeed pitot tubes had become unreliable. I suspect he had too many things to think about - OK if you practice enough but not good if you have to look up what to do! We will probably never know exactly.
 

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Are aircraft "overautomated"?
« Reply #31 on: 31/08/2011 03:27:57 »

 

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