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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 14th Jan 2015, 05:11
  #1961 (permalink)  
ekw
 
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WSSS

My understanding of a deep stall is to describe a state where the elevators become inoperable due to insufficient airflow and the aircraft cannot pitch out of the stall. This happens more in T tails because the disturbed air from the wings catches the tail at a certain angle, but I suppose if any heavy aircraft is below a certain speed then elevator deflection may not be sufficient to move the AOA - you need to roll as well.
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Old 14th Jan 2015, 05:13
  #1962 (permalink)  
 
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@Ian W

The accountants (aka beancounters) will then look around for savings and an easy area is training.
Regulators create the standards (including for training). If pilots or airlines fail to meet those standards and don't face sanctions for such breaches, well... I blame the regulators (and, ultimately, the political climate that equates free markets with unregulated markets).
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Old 14th Jan 2015, 05:21
  #1963 (permalink)  
 
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Unstalling a wing is very simple, decrease the AOA to less than the stall AOA.
How right you are! But .......

1. Too late
You need enough aerodynamics on your elevator. You might not have it when in a deep stall, or when you are way too slow already.

2. Too little
You need the authority by the FBW. Its action computers might not have enough travel to cope.

3. Too 'magentised'
You need the authority of the protections. They might be fooled by sensors and not allow unloading, and/or they might be too complicated to override ......

4. Too inexperienced
You need the guy at the stick realise that he's in a stall! Even with 20k hours he might have been told this can't happen, or he might have never experienced such a situation, just read in the OM what to do in case the thing happens that can't happen per superior design ......

Pick your numbers, they pretty much apply for many of the latest accidents.
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Old 14th Jan 2015, 05:27
  #1964 (permalink)  
 
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if any heavy aircraft is below a certain speed then elevator deflection may not be sufficient to move the AOA - you need to roll as well.
elevator deflection with full nose up on the stab may not be sufficient to move the AOA, you mean...
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Old 14th Jan 2015, 05:30
  #1965 (permalink)  
 
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WSSS: I truly doubt that FBW had anything to do with this incident.

"We all know how easy it is to recover from a stall. All pilots learn that before they are released for their first solo. You learn stall recovery in the first 10 hours of your PPL flight training."

Many argue that "true flying skills" are no longer present in today's younger pilots due to FBW and the video game mindset.

I believe that the problem is more the fact that since the days of the 727, the concept of the "coffin corner" is no longer taught. You can't just climb as aggressively in the thin air as you can at a lower altitude without stalling.

A stall in PPL training with a fat wing, in fat air is an easy fix. Max power, lower the nose some. And you are never trained in full stalls again.

I was trained in the jet only the "approach to stall recovery",

It wasn't till several of our company aircraft entered moderate stalls at high altitude that that they trained us in the proper recovery.

I was shocked at the altitude loss and pitch attitude required for recovery.

And still, few airlines teach this in the sim.
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Old 14th Jan 2015, 05:45
  #1966 (permalink)  
 
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Cabin positions of victims recovered thus far:

https://mobile.twitter.com/TheNewOce...904448/photo/1
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Old 14th Jan 2015, 06:00
  #1967 (permalink)  
 
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It wasn't till several of our company aircraft entered moderate stalls at high altitude that that they trained us in the proper recovery.I was shocked at the altitude loss and pitch attitude required for recovery.
And still, few airlines teach this in the sim.
So you were trained for stall recovery in the sim? Who put your aircraft into the stalls required, and recovered from them, to provide the data for the sim?

Is this not the basis for Airbus reluctance to do sims on real stalls, that they do not have the data required to make the training meaningful/realistic and that they prefer to train to avoid the stalls in the first place.

Did the pilot-engineered stall on AF447 provide any useful data for an Airbus sim? The problem possibly being that there was no recovery and that at some stage a "recovery" might have "torn the wings off" anyway?
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Old 14th Jan 2015, 06:05
  #1968 (permalink)  
 
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Crash position indicators are a solved problem.

Crash position indicators a the result of research into ejectable radio beacons that would deploy in a crash. The problem was solved 60 years ago and implemented first in military aircraft five decades ago. I'm not sure what this forum's policy is on Wikipedia, but this is worth a look.

Crash position indicator - Wikipedia, the free encyclopedia
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Old 14th Jan 2015, 06:53
  #1969 (permalink)  
 
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If not push, just release the backpressure

I truly doubt that FBW had anything to do with this incident
As most modern FBW aircraft do also have some sort of auto trim logic in their control system, there is no more backpressure. You really have to push to tell the computers that you want to go back to the condition you were in before you pulled. You can release the backpressure and your control system still remembers your pull command and delivers what you asked for.
Because of this, FBW has quite a lot to do with any incident/accident involving the flight controls, as it is always more than just replacing control cables with electric wires. It is a different control system requiring different flying technique. Quite similar to the difference between powered flight controls and pure mechanic ones. Backpressure on a DC-3 is quite different from backpressure on a 747...

And still, few airlines teach this in the sim.
I would not trust the sim in those situations anyway, it is far outside the range it has been developed for. For most aircraft the numbers in the sim computers will simply be extrapolated, and not resulting from flight test data.
they prefer to train to avoid the stalls in the first place.
It does however not do any harm to also train how to recover from it. First priority should of course always be avoidance. Just like CBs, terrain, traffic...
We should also remember that the regulation is not asking for spin recovery of multi engine aircraft or stall recovery of large transport aircraft. All that is required is recovery from the situation when the warning is triggered. It is not required to fly full stalls in flight testing. And matter of fact, several prototypes were lost during stall testing in the past, so it is probably wiser to avoid it altogether.
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Old 14th Jan 2015, 08:52
  #1970 (permalink)  
 
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To say "Pilots were trained" for Stall Recoveries in their PPL phase, and expect that to have any relevance years later, when both time has passed, and flying very different aircraft, is not valid IMHO

In my RAF days, exercises such as stall recoveries were required to be practiced, IIRC, every 28 days. Along with UP recoveries etc.

From my experience, the 3 yearly "training cycle" of such items in typical airline Sims, and also the "canned" / tame nature of the exercises, renders them nigh on useless I reckon the "benefits" of being refreshed last for maybe 2-3 months, then I think I am back where I was prior the sim.

There is little point in practicing "stall recoveries" unless and until we are proficient in recovering at the approach to the stall. And of course if we are proficient at the recovery at the warning stage, there is less merit in practicing the full stall & recovery.

Does anyone seriously believe the AF447 pilots had any chance of recovering once they got to <60KIAS / 40 AoA? Yes - the aircraft was theoretically recoverable, but given how they got to that point, I think the chance was almost nil. They had so seriously lost SA that the very bold control inputs and attitudes required I do not see happening?

The solution, if we wish to reduce LoC accidents (which are very rare), is to ensure pilots are genuinely competent in attitude flying, stalls even spins, UP recoveries - and keep current 2-3 times a year minimum. That is an awful lot of aerobatic aircraft hire, and will kill a lot of pilots in accidents. It won't happen, and I suspect we will just continue to see a small number of LoC accidents...
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Old 14th Jan 2015, 08:56
  #1971 (permalink)  
 
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Deep stalls are not reserved for T tails only. I have trained deep stall in the 737 sim several times, both before and after AF 447. Deep stalls are way different than regular stall, and can take thousands of feet to recover from.
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Old 14th Jan 2015, 09:03
  #1972 (permalink)  
 
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According to Twitter: Singapore vessel MV Swift Rescue locates fuselage
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Old 14th Jan 2015, 09:03
  #1973 (permalink)  
 
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Singapore vessel MV Swift is saying it has located the fuselage of QZ 8501. An ROV has been sent down to photograph fuselage plus wings. (Jackson Board for Channel News Asia who seems to be fairly on the ball with this.)

Edit: a good job as conditions in the crash area are difficult today.
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Old 14th Jan 2015, 09:03
  #1974 (permalink)  
 
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Volume is correct about the inability of flight simulators to accurately replicate the real aircraft's post stall behaviour. Test pilots do not take commercial aircraft that far into the stall regime, and certainly not at high altitudes, it is simply far too dangerous. Therefore all the models used in simulators for post stall behaviour are based on extrapolated data and wind tunnel experiments.

Pilots should not assume that what they see in the simulator post stall is correct. In fact it is positively dangerous to do so.

I would be very interested to hear from 'those in the know' what the industry is doing about the conclusions of the work done by the IPTC. Why are the regulators dragging their heels over requiring improved training? Are airlines implementing the recommended improvements despite a lack of response by the regulators?


See:- ANALYSIS: Modernising global airline pilot training - 1/12/2015 - Flight Global
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Old 14th Jan 2015, 09:29
  #1975 (permalink)  
 
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Second picture above appears most telling - consistently with the tail section of the wreckage, the left side of the fuselage appears to be torn away midway along.
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Old 14th Jan 2015, 09:34
  #1976 (permalink)  
 
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Originally Posted by Volume
It is not required to fly full stalls in flight testing.
It depends on what you mean by "full stall". The regulation calls for the speed to be reduced until the stall is identified, and lists the criteria that represent acceptable stall identifications. Recovery is started as soon as the stall is identified, i.e. it is not required to investigate 'deep' penetrations into the stall regime.
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Old 14th Jan 2015, 09:44
  #1977 (permalink)  
 
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I cannot believe the uniformed nonsense being posted in respect of transport category aircraft stall testing, stall characteristics and what is required to demonstrate compliance with the certification standards.
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Old 14th Jan 2015, 09:51
  #1978 (permalink)  
 
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no need to kill a lot of pilots to teach basics

NigelOnDraft: Sorry , but -- without debating the cost & headaches of teaching people how to really fly -- I find the conclusion that this "will kill a lot of pilots" unjustified. In more than 20 years of teaching advanced aerobatics, as well as stalls/spin and unusual attitudes (including, for a time, dozens and dozens of Ab Initio China & Gulf Airline students) I, and my then colleagues, did not have a single aerobatic accident. Pray tell why this should change.

"The solution, if we wish to reduce LoC accidents (which are very rare), is to ensure pilots are genuinely competent in attitude flying, stalls even spins, UP recoveries - and keep current 2-3 times a year minimum. That is an awful lot of aerobatic aircraft hire, and will kill a lot of pilots in accidents. It won't happen, and I suspect we will just continue to see a small number of LoC accidents...
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Old 14th Jan 2015, 10:12
  #1979 (permalink)  
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From the photos of the wing, it looks as though the flaps have been extended?
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Old 14th Jan 2015, 10:13
  #1980 (permalink)  
 
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@zzuf


I cannot believe the uniformed nonsense being posted in respect of transport category aircraft stall testing, stall characteristics and what is required to demonstrate compliance with the certification standards.
I take it you meant "uninformed nonsense", in which case I would simply say that Gysbreght is better informed than most posters here on certification as John T may well confirm.
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