Originally Posted by TTex600
(Post 7341382)
Uh, you're making a distinction without a difference. The Airbus can NOT be flown without the computers.
Why? I'm not arguing that point. The pitot's iced up, therefore Garbage In, and the computed airspeeds turn to Garbage Out. Subsequently the computers give the airplane (which they can no longer fly) to the human. Leaving the human to deal with it. The pilots were left without the vaunted computer protections... while you and others lay in your warm beds dreaming about how the system really does allow pilot full control. You just won't give up will you? IIRC, you claim no connection to Airbus, AirFrance, etc, but you have made claims in this very quoted post to know the intent of the design. How do you know? All true I assume. Except that your little toy computers don't seem to be able to replace humans and humans would appear to prefer a speed stable airplane. And if you honestly think I'm pro- pilotless airliners or that I'm some kind of advocate for full automation then you clearly have not read my posts. What bothers me is the repetition and propagation of press scuttlebutt as fact. Computers are great at the dull and repetitive tasks that keep an airliner on course, but they're singularly lousy at being able to deal with situations outside of the norm. [PS: Spinmeister? If anything I'm anti-spin! Here's the deal - the idea that the A320 was the first step towards fully-automated airliners? Spin. The idea that the Airbus FBW protections would routinely override human pilot input? Spin. The claim that a certain A320 on display "thought it was landing"? Spin. ] |
Originally Posted by CONF iture
(Post 7340849)
1) To work properly, automation and protections need reliable data.
If data are known to be corrupted the simplest thing to do would be to cancel automation : Direct law - No autotrim Every Boeing pilot flies that way in manual flight, is it an issue ? At Schipol the 737 autotrimmed into stall and trim was never touched in recovery (nor was thrust properly applied, but had it been the result might have been worse due to trim - see e.g. http://www.pprune.org/rumours-news/3...ml#post4787036 ). Ethiopian (boeing again...) at Beirut was mistrimmed, manually, into stall and crash. At Perpipnan they did drop into direct law... and it didn't help. They were trimmed up into stall and never changed it. Had they stayed in alternate with auto trim would they have managed the recovery ? Would autotrim have helped or hindered them ? 2) ALT LAW + Autotrim amplify the severity of the stall. On the other hand if stick is pushed forward, autotrim (if trim was NU into the stall) will help to reduce AOA and reduce chance of secondary stall when compared with not touching the trim, no ? PS : Thanks to both of you for you reply. It is unacceptable the BEA simply ignores the matter. Resources are finite, and I don't think the investigation necessarily has the remit to go further into things that may be interesting but not causative or relevant to the outcome of the accident. There are areas I'd have liked more depth on - but I think they've eliminated them too. My impression looking at the HF slant in the report is that BEA have clearly focused on (1) rather than (2) from: (1) why are crews (not just this one) stalling and pulling back in stall (2) why is the trim following the pilot command when (1) happens So, are they correct to prioritise (1) over (2) - which does not mean they ignore (2) - which problem needs fixing to prevent crashes ? Which problem will become a non-problem if the other is fixed ? |
Originally Posted by CONF iture
(Post 7329629)
QF72 A330
Just short memory ... or desire to look the other way ? BTW, still no fix, just the same OEB to try to beat the dysfunction ...
Originally Posted by jcjeant
So for you .. the judges have vested interests and so they will misusing the recorded data ?
That's new for me .. I suppose you have references .. The State conducting the investigation of an accident or incident shall not make the following records available for purposes other than accident or incident investigation, unless the appropriate authority for the administration of justice in that State determines that their disclosure outweighs the adverse domestic and international impact such action may have on that or any future investigations.
Originally Posted by Retired F4
Are you in disagreement here with BEA?
Originally Posted by BEA
the conditions in which airline pilots are trained and exposed to stalls during their professional training and the process of recurrent training does not generate the expected behaviour in any acceptable reliable way.
Originally Posted by Retired F4
Well, BEA is adressing this matter again, and you disagree here again?
Originally Posted by HazelNuts39
Maybe there is merit in developing a system that reliably detects a stall and announces that condition unequivocally to the crew.
Originally Posted by safetypee
At best we only have a small snapshot of what occurred in the flightdeck, and can only speculate on the crew’s mental activity.
Originally Posted by Lyman
Here is BEA definition of the depart. Do you see any reference to STALL?
Originally Posted by Lyman
Neither was there Stall Buffet sufficient to announce STALL onset.
Originally Posted by Lyman
There was no drastic increases in drag, in fact drag was decreasing, due to the lessening of velocity.
Originally Posted by Lyman
There is a profound difference between "loss of..."
And "Unreliable...."
Originally Posted by Lyman
So yes, the issue was they were lost at STALL,
Originally Posted by Lyman
What did the crew do that was unique?
Originally Posted by Retired F4
If it would have been a simple stall recovery maneouvre, why did BEA use those cryptic words?
Originally Posted by CONF iture
But first things first, the BEA had to evaluate what was the influence of the autotrim in the process.
Originally Posted by BEA
Throughout the flight, the movements of the flight control surfaces were
consistent with the pilot’s inputs.
Originally Posted by BOAC
References appearing to the Airbus 'stall recovery pull-up' manouevre. Is this right?
Originally Posted by Dozy Wannabe
According to Clandestino, Alternate Law handling is trained to assume a worst-case scenario (i.e. all protections lost).
Originally Posted by Lyman
think he was honestly trying to regain a cruise Pitch or thereabouts.
Originally Posted by Lyman
At what point then do you consider the a/c STALLED?
Originally Posted by Lyman
As designed, the autotrim helped to put deeper the aircraft into the stall ...
Originally Posted by IcePack
I find the Boeings airspeed indications more damped than the AB
Originally Posted by IcePack
I would say only moderate but the speed indications would have had you believe the aircraft was out of control.
Originally Posted by RR NDB
Why Airbus SAS design delegates to the crew UAS diagnosis?
Originally Posted by RR NDB
On UAS early warning: Technically speaking this is VERY EASY.
Originally Posted by TTex600
Everybody in this Godforsaken business eventually hides behind the law that places final responsibility in the pilots hands.
Originally Posted by CONF iture
Sidestick neutral, the THS would have rolled the same way.
Originally Posted by Dozy Wannabe
It flies just as well under Alternate Law - and unlike the Cessna, A310 or Boeing, manual trim is more difficult because - as has been said - there is no direct or artificial feedback.
2. It is BS perpetuated by some. It is very easy to trim Airbus in direct law using wheel. Fact that you move stick and not just release the pressure as you trim did cause some concern to me when I read the manual. It is absolutely easy to do, folks who keep spouting it's a problem have never tried it.
Originally Posted by TTex600
The Airbus can NOT be flown without the computers.
Originally Posted by TTex600
Subsequently the computers give the airplane (which they can no longer fly) to the human. Leaving the human to deal with it.
Originally Posted by TTex600
The pilots were left without the vaunted computer protections while you and others lay in your warm beds dreaming about how the system really does allow pilot full control.
Originally Posted by Dozy Wannabe
Neither can the B777,
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UAS early warning
My role here is limited. I consider first to assertively say what i am convinced, absolutely sure and this must be said. Because was important in the crash.
I am available to explain by voice the "practical solution" to an interested pprune member. Simple, just call me and i can teach what to do. Actually most EE knows that. Simple DSP techniques used extensively in the industry. In simple words: We need to perform a DSP of the air (analog output obviously) speed information and: 1) Inform IMMEDIATELY to the crew the UAS onset. 2) Block IMMDIATELY GI to ELIMINATE GO (GIGO played a pivotal role) In a previous post i mentioned an Airbus SAS paper that shows the opposite: The crew must diagnose. IMO this is a serious error. In many aspects. So important specially when you do not have redundancy at all. (Important sensors failing SIMULTANEOUSLY). :{ Degrade a System and wait for the crew diagnose is a COMPLETE ABSURD. The chances could be dim even for a designer acting as pilot depending on behavior of the System. The approach used is WRONG. And SHOULD be changed: 1) UAS DSP detector 2) Actions by crew/System or System/crew |
DSP of air speed information
Same reason Boeing does... computer can't recognize it. We are discussing here a total failure of an Airbus SAS product. FYI, a very cheap processor can do it EASILY. A DSP of "audio" frequencies or less. :{ |
Originally Posted by Clandestino
(Post 7341467)
1. You probably meant direct law, ALT has autotrim
2. It is BS perpetuated by some. It is very easy to trim Airbus in direct law using wheel. Fact that you move stick and not just release the pressure as you trim did cause some concern to me when I read the manual. It is absolutely easy to do, folks who keep spouting it's a problem have never tried it. She can. Why are we bringing opinions that are blatantly wrong into discussion? We are not flying passengers in bloomingly unstable Su-27! RR_NDB - a modern DSP will not pass certification on the basis of MTTF. As a backup it's plausible, but as aprimary replacement for pitot tubes it won't work. |
Originally Posted by Clandestino
It flies very nicely without any computer intervetion, with direct stick-to-control-displacement of direct law.
|
@TTex600:
Clandestino is a former FBW Airbus line pilot, now flying ATR turboprops. Some clarification should be made in that what he is describing is Direct Law, where the computers pass the sidestick inputs direct to the flight surfaces. The FBW Airbus models will not fly if the electrics are lost altogether - but this is also true of any other modern airliner you care to name. |
Quote: Originally Posted by BEA Final Report (English) p.22-23 At 2 h 10 min 51, the stall warning triggered again, in a continuous manner. The thrust levers were positioned in the TO/GA detent and the PF made nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) began a nose-up movement and moved from 3 to 13 degrees pitch-up in about 1 minute and remained in the latter position until the end of the flight. That's a factual account of the THS behaviour - and the limit of what the BEA can say. Conf asked about a analyze .... I find (like him certainly) that what you quoted from the report is not a analyze .. But maybe (or likely certainly) the BEA think that a analyze about is not relevant ... |
Originally Posted by DozyWannabe
Clandestino is a former FBW Airbus line pilot, now flying ATR turboprops. Some clarification should be made in that what he is describing is Direct Law, where the computers pass the sidestick inputs direct to the flight surfaces.
The FBW Airbus models will not fly if the electrics are lost altogether - but this is also true of any other modern airliner you care to name. I've just checked my A320 FCOM (27.40.5) and it indicates that an ELAC (that's a flight control computer just in case the peanut gallery isn't aware) provides "direct pitch and roll" along with other functions such as normal pitch and roll. If my books are wrong, please give me a link to a better, more in depth, manual. Then tell my Director of Training about it as well, as he seems to think his manuals are airbus compliant. Edited to add: I'm still waiting for the instructions on how to put an Airbus in direct law. I'd like to try and fly it that way if I ever get assigned to a mx flight. |
Originally Posted by TTex600
(Post 7341536)
So you agree with me. Without a computer, you can't fly an airbus.
Again, try and stay on topic. My post didn't say that you can't fly an airbus without electricity, it said that you can't fly an airbus without computers. Edited to add: I'm still waiting for the instructions on how to put an Airbus in direct law. I'd like to try and fly it that way if I ever get assigned to a mx flight. If you want to force Direct Law in flight, then the only way to do so is to sabotage the systems. I don't understand why you'd want to. |
What then did cause the aeroplane to decelerate with maximum thrust, if there was no drag? Things we discuss seriously on professional pilot's forum are sometimes unbelievable. |
I have never flown an aircraft, mostly Boeings, that wouldn't fly just fine with all generator power gone and 30 minutes on the standby instruments then indefinately to destination once clear of weather. Losing an aircraft at FL350 because the pitot system froze up would not be an emergency. If you follow the crazy procedure of going into a 5 degree pitch up and climb power then you will soon get an overspeed. Everybody knows that. Maybe the PF forgot he went to alt rules and reacted as he did pitching up into an impossible 14 degree deck angle because he thought Airbus said you can't stall it so just pulled back and held it for over 3 minutes.
My personal experience is once you become a monitor of automation you gradually lose your hands on flying skills. I experienced it once going from the MD80 back to captain on the 737 200 which is a baby step compared to the AB. I never let it happen again once in the 757. I kept up my hand flying skills to be safe. |
Originally Posted by RR NDB
My role here is limited. I consider first to assertively say what i am convinced, absolutely sure and this must be said. Because was important in the crash.
Originally Posted by RR NDB
Simple DSP techniques used extensively in the industry.
Originally Posted by RR NDB
We are discussing here a total failure of an Airbus SAS product.
Originally Posted by RR NDB
Degrade a System and wait for the crew diagnose is a COMPLETE ABSURD.
Originally Posted by Dozy Wannabe
No - I meant Alternate Law, but the sentence that followed it referred to Direct.
Originally Posted by Dozy Wannabe
I was working on the assumption that it would be harer without tactile feedback, but if you think otherwise...
Originally Posted by Dozy Wannabe
The point I was making is that all modern airliners rely on computers whether being flown manually or on auto these days. If the electronics quit, it's a lot more difficult to fly them.
Originally Posted by TTex600
Really? And you know this how? Are you, were you, an Airbus test pilot? Just how is a line pilot to accomplish this state of control?
Originally Posted by Dozy Wannabe
Clandestino is a former FBW Airbus line pilot, now flying ATR turboprops.
2. As these are anonymous forums the origins of the contributions may be opposite to what may be apparent. So if someone makes a claim he is a pilot of this or that and then goes on making absolutely false claims about the equipment he is supposes to fly on, it absolutely doesn't imply that the pilots of said equipment are not acquainted with their mount and that we should blame the manufacturers for providing inadequate manuals.
Originally Posted by TTex600
I'm still waiting for the instructions on how to put an Airbus in direct law. I'd like to try and fly it that way if I ever get assigned to a mx flight.
2. mx flight programme covers way to achieve direct law, if checking the handling in it is required.
Originally Posted by Dozy Wannabe
You're in Direct Law whenever you land.
Originally Posted by bubbers44
If you follow the crazy procedure of going into a 5 degree pitch up and climb power then you will soon get an overspeed. Everybody knows that.
Originally Posted by jcjeant
Add Newton to the equation (the apple) and your explanation of the deceleration will be complete (it's not only for artillery matter)
Originally Posted by bubbers44
Maybe the PF forgot he went to alt rules and reacted as he did pitching up into an impossible 14 degree deck angle because he thought Airbus said you can't stall it so just pulled back and held it for over 3 minutes.
|
Hi Clandestino,
Originally Posted by Dozy Wannabe You're in Direct Law whenever you land. Originally Posted by Clandestino Actually, it is only in rollout. http://blackholes.org.uk/PP/Flight%2...transition.jpg It's NOT the same as the in flight Direct Law: FCOM 1.27.30 P6. "With the aircraft in the clean configuration, the maximum roll rate is about 30° per second. With slats extended, it is about 25° per second." Ground mode aileron deflection, when above 80 knots, the effectiveness of roll control, ailerons and roll spoilers, is reduced by the half (e.g. aileron deflection limited to 50% of maximum deflection). See, Report: Lufthansa A320 at Hamburg on Mar 1st 2008, wing touches runway in cross wind landing Easy for the unwary to get caught out. Simples? |
Surprises can generate additional problems
Hi,
Clandestino In a K.I.S.S. approach: 1) An extra resource capable to inform UAS onset would be useful? 2) Block garbage to enter System would be better? The crew processed adequately the surprises they received? I would prefer to be informed immediately by an UAS detector resource than to be bombarded by the results (of the UAS) in the System. False positives would be a problem? IMO, not. My rationale is: I don´t like the approach to diagnose UAS by System output. As showed in an Airbus SAS paper mentioned in an earlier post. This can be improved and in AF447 case seems very important. Thanks to mention Solipsism. Rich issue. Maybe could be applied to Laser based AS sensors. Definitively not here in processing analog information coming from current technology. This is real long time ago. I started my career using vacuum tubes (big ones in NDB, HF gear, etc.). In the Analog world. The inputs i prefer (for my decision making) are analog signals. Not garbage processed by Systems. Sadly, the (non adequately trained) crew of AF447 were: Surprised by the System output and worse: Had to process garbage generated by the System. And failed in their decision making. Actually, worse than that, never realizing (in time) what was going on... :{ |
I don't think the test pilots that approved the 5 degrees nose up and climb power tried it with blocked pitot tubes. The trapped pitot pressure and the decreasing static pressure would cause an indicated airspeed increase and at some point an overspeed warning.
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bubbers,
In the case of AF447 the pitot drains remained open, hence the pressure was not trapped. I guess the procedure designers looked at the scenario you postulate, and decided that 5°/CLB would allow sufficient time to get more accurate settings from the QRH, or to analyze the situation and ignore the warning if necessary. |
HN.... Why would the boffins select a climb, at all, in the first place? If one is in that narrow band of a/s, seems like given the record, higher airspeed might be worth the risk, rather than a climb into the lid, a risk of STALL, or power and lift ceilings being passed, as 447 did? She maxed at 38K, and got their in a flash, so why not 0 degrees and no power increase, or even a reduction in Thrust.
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Misleading info
Even in a test environment misleading is dangerous.
For the sake of Graceful degradation, increasing crew chances to act precisely. Thiels 727 is a good example of what can occur. Ignore warnings can be lethal. Better to have decent man-machine interface behavior even during transients and anomalies. This is possible? I think so. R&D must be done to improve current situation. |
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