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Pilot Commands TOGA; A320 lands anyway

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Pilot Commands TOGA; A320 lands anyway

Old 11th Jun 2001, 01:36
  #101 (permalink)  
Haas_320
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Yihaa as far south as SXM DWI beat that.
 
Old 11th Jun 2001, 02:12
  #102 (permalink)  
Lu Zuckerman
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To see how these problems got started please go to Rumors and News and check the archive for the last ten days and click on HOW SAFE IS THE AIRPLANE THAT YOU DRIVE.

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The Cat
 
Old 11th Jun 2001, 04:38
  #103 (permalink)  
vikingwill
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The thing that really bothers me about this entire issue is that fact that Airbus expect to have validated update software soon. Presumably the flawed software was validated, but clearly the validation process itself needs to be severely questioned otherwise one has to ask what other forseeable risks are present. I accep that unforseeable risks can not be eliminated, but surely to God wind shear is forseeable, and if the incident (accident) was recreated in the SIM, how on earth was this missed in software validation! There are very good International Standards on risk analysis and management in many fields - were (are) these not used?
 
Old 11th Jun 2001, 13:56
  #104 (permalink)  
Frederic
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Haas-320, thanks for enlightening me, I learnt something new again...
I know about the derotation law, but I seriously doubt the aircraft would stay in normal law because if it would that would impose a problem after touchdown. Once on the ground the amount of G is of course one, and so a pilot imput demand of , say 1,2 G might result in a controls runaway since it is impossible to reach 1,2 G! So somewhere along the way the aircraft must convert into ground (direct) law? I might be totaly wrong of course, but this is how I understood it. Also if it would stay in normal law, it would conflict with lowering the pitch attitude since normal law tries to keep one G and lowering the nose would result in less than one G.
Your idea of providing pressure sensors is a good one, but on the other hand you will need to train your pilots to recognise when the system needs to be overriden. The purpose of the system is to provide max alpha immediatly with full aft stick. If you allow the pilot to override the system, he will do it also when increasing the alpha will decrease the performance. There is little use in providing a protection system if it can be so easily overriden since the nature of a human is to think he is right. The tiny (although apparently present) risk of the system malfunctioning does not weigh of against the fact that it provides G protection and/or optimum alpha and so performance. If you put two identicial aircraft in the same conditions at the same speed and altitude, the one that provides you with max alpha immediatly will always win in a "pull-up" contest, unless you are above the speed where you can pull more than -in this case- 2,5G. And I am now talking about alpha protection, not about the derotation law wich I never tought was a good idea anyway. But even then the risk of hitting the mountain because you can pull 2,5 instead of maybe 3,5G does not weigh of against you breaking the aircraft in two due to overstress. An ideal FBW system would be one that would have a variable G-limit system continuously weighing of the risk of overstressing the aircraft taking into account its actual weight and load distribution against the risk of hitting an obstacle due to a to low available G-limit. I'm talking about scientificly calculating the risk. I'm sure it is possible to devellop a system like that certainly taking into account EGPWS is now certificated. But this is aviation, and certifying something like that would take years. And AI/FBW slaggers, before you declare me mad again, this would be a system that would provide the pilot with more authority and it would not of course pull up by itself. The imput would be pilot commanded. A lot of people tell me I should stop smoking funny cigarettes when I talk about my idea, but hey, at least I come up with one.
 
Old 11th Jun 2001, 16:39
  #105 (permalink)  
Flight Safety
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Frederic,

What is needed is a Direct Law override button, which I understand the Boeing FBW system has.

This obviates the need for a "risk analysis" computer. Can you imagine trying to override 2 layers of software in an emergency situation (beyond the FBW software's ability to cope). Not only would have to override the FBW computer software, but also the "risk analysis" software that's trying to decide if it should allow you to override the FBW software or not.

The Direct Law override button will do nicely thank you.

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Safe flying to you...
 
Old 11th Jun 2001, 21:02
  #106 (permalink)  
TvB
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vikingwill and all:


found this in the last AW (issue June4th, page 22):


" Airbus' revised software covering the A319/A320's automated angle-of-attack (AOA) protection is scheduled to obtain certification by the end of the month. The software now being modified was not the A320 series' original AOA protection, Airbus officials stressed. The in-service protection's software was altered two years ago when operational feedback indicated that heavy wind shear could bring aircraft too close to a stall warning. However, the modification went "slightly too far" and needed to be revised, the Airbus officials noted..."


To me this still doesn't answer what they have designed into these software programs in case of a go-around command by the crew. I believe the a/c should respond to this by all means and not contradicting or interfere with any other modes other than "climb".


I was told a go-around with an A320 would still be possible, even after touch down, but in this case you'll get a master warning (quite disturbing). Apparently this did not work in Bilbao at all, so therefore the parameteres have to be revised.


And I agree vikingwill, the original/altered certification is in question here. But I doubt that in any office of a regulatory/oversight administration we would find people qualified enough to make such a decission. Those who are capable are more likely working on the other side, in the Industry, as they get 3 to 4 times the pay there and have access to all data and design specifications (I believe some of that stuff is still considered "propriatory information" and the manufacturer will not hand it out).


Usually the governing questions in this regards are: "What is required by the certification?" and "How is the aircraft going to perform it?"


The later might become reduced to: "Can the aircraft perform as required?" Answer: "Yes" Stamp: "Approved"

TvB
(independent) aviation editor
www.aviationsafetyonline.com



[This message has been edited by TvB (edited 11 June 2001).]
 
Old 13th Jun 2001, 01:50
  #107 (permalink)  
Frederic
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Flightsafety, you seem to jump into "negative thinking" to quick. Try to find reasons why the system would work, instead of only why it wouldn't. You would not need a "second layer of software" to get this system to work and a minimum amount of 2,5G would always be available as it is now. So it would always provide you with minimum or additional performance. I think people are having problems accepting a system like this because they think it would be very compex. It is very simple to calculate that risk. Here is the logic:

1. Get me (from a database and/or G load and current mass quantity and distribution sensors) the maximum current G-loading the aircraft can handle at this moment before there being a risk of it breaking into two bits.
2. Get me the distance, size and closing rate of the nearest obstacle in the flight path. (Easy peasy, since EGPWS has got all that info ready and certified!) Calculate how much G I need to avoid it.
3. Do this 200 x per second and keep updating the FBW with the lowest of the two values.
Et voila, you have a system that will protect you the best it can.

The problem of a Direct law button is that people would misuse it. If a pilot pulls up for an obstacle and "guesses" he will not make it he WILL push that button. So that means that the whole point of having a protection system is wasted since the pilot will override it when he panics and might damage the aircraft, thereby increasing the risk unneccesarily. Don't think aircraft are infinitly strong. Ask any aircraft engineer: aircraft have very definite G limits, and going aver them WILL brake them. Of course the 2,5Gs AI takes as the maximum are very conservative and not addapted to the current state of the aircraft. If you want to minimise risk you have to calculate risk, not guess it. Take for example sheduled performance: I've seen so many pilots taking their hands of the thrust levers before V1 because they think "the aircraft will never stop before the end of the runway". But 1: it has been calculated to do this, 2: it has been tested and physically proven to be able to do this and 3: how are you going to know by just looking? Defenitly if you've probably never done an abort from V1 in your life (like a lot of pilots never have.
The problem is that in an emergency you don't have time to calculate your performance manually so you need to have done it either on forehand or have a really fast computer calculate it for you in real time.
So you see flightsafety, in my system the "risk analasys" software IS the FBW software and does not consist if an extra separate layer to be overriden...

[This message has been edited by Frederic (edited 12 June 2001).]
 
Old 13th Jun 2001, 15:49
  #108 (permalink)  
stator vane
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bunyip:

just noticed your statement about how an american will attack when criticized even when it is right and then you really go off the edge and put an airbus in the same sentence.

the fact that the individual you refered to happened to be an american, is not a proper basis for your statement in such general terms.

some americans will actually listen or read as the case may be.

but is it an "attack" to point out the fact that you may be a bit too general in your conclusion?

 
Old 13th Jun 2001, 22:39
  #109 (permalink)  
Brad737
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frederic
Your post tags you as an extremely technically oriented person. You are well spoken. Your argument, however, is flawed.
I would take issue with your contention that this "direct law" button would lead to abuse. Professional Pilots rarely find themselves in such a position as to require the overuse of this button, we see to it that these situations do not occure with regularity. That's what experience is for.
Secondly, if I were to push this button, thus denying myself of "programed" protection, I can state with utmost certainty that I will not snap my aircraft in two in a 3G pullup or degrade my airspeed to a stall. Anyone likely to do so does not live long enough to occupy the pointy end of a commercial aircraft.
Your post illustrates what is wrong at AirBus headquarters. You think the pilot is something to protect the public from, not a highly skilled and experienced asset to be incorporated and trusted into the cockpit. I am not anti-FBW, I think it a fantastic development. I simply demand that in a situation that I deem prudent(software anomally, unforeseen event by programmer, etc) I have the ability to bring 10,000 hours of experience into play.
 
Old 14th Jun 2001, 00:06
  #110 (permalink)  
beardy
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Brad737, you may have 10000hrs of experience, others don't. You may believe that this will lead you to being infallible, others wouldn't.
 
Old 14th Jun 2001, 01:22
  #111 (permalink)  
Brad737
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beardy
If that's the message you got from my post then I should be faulted for it's tone, though not it's content.I was not bragging, I was simply holding myself up as the average airline pilot for use in my example.My many hours do not make me infallable but they do provide for superior adaptability and judgement in an infinitely fluid environment such as aviation. A programmer can only account for a finite number of possibilities. I see a disparity here.
AirBus' philosophy reminds me of a joke about the future cockpit containing a pilot and a dog. The pilot's job is to feed the dog. The dog's job is to bite the pilot if he touches anything.
 
Old 15th Jun 2001, 10:04
  #112 (permalink)  
Haas_320
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From sim experience I have learned that emergency procedures need to be STRAIGHT FORWARD and SIMPLE. Other wise I GET IT WRONG, (let the one who consistantly get it right cast the first stone) It would be nigh impossible to teach the correct use of a non intuitive system like a direct law push button. Just having the take over push butten couses enough confusion.
 
Old 15th Jun 2001, 10:56
  #113 (permalink)  
High Volt
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Airbus = too clever: I can't understand software nor do I think that I should be expected to. Give me a Boeing airplane, it knows its place.
 
Old 15th Jun 2001, 21:50
  #114 (permalink)  
Flight Safety
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I guess my feelings are similar to Brad737's.

The autopilot has had a release button for decades. That button is needed for two reasons. One, the autopilot is a system that's not used all the time, so turning it off and on is normal for that sytem. But the second reason for the autopilot release button is because the autopilot can and does fail, and pilots are trained for this and it's practiced in the sim.

Why then should the FBW envelope protection system be without a release button? Granted this system is not cycled off and on the same way as an autopilot, but the system is subject to failure just as an autopilot is. I agree with others that FBW envelope protection is a great innovation and a great system, but why should this particular system be so "sacred" as to not allow the pilot to override it in an emergency? Why should this particular system have a different design philosphy towards possible failure and safety, compared to the autopilot?

Now what I'm about to say, I've withheld from saying for months on these forums looking for a right time to bring it up, and this appears to be the right time.

Is there any connection between the Airbus design philosophy of their FBW systems, and the non-US civil avaition authorities that allow low time pilots in the FOs position?

I'll try my best to articulate what I mean, and the joke about the dog and the pilot might apply here. We all know that some feel that the future of flying is pilotless aircraft. Some argue this future will be safer, and some argue is will be more cost effective.

Is it possible that both considerations (safety and cost) are at work in the Airbus design philosophy, at our current stage of technology development? FBW envelope protection has clear safety benefits, however lowering the requirements for pilot experience (thus lowing costs) does not. So is the design philosophy of Airbus FBW systems driven purely by safety considerations, or is there also an attempt to build in a requirement to allow lower standards of flying experience in the cockpit, creating what I would call a "mixed objective" design philosophy? Is there an attempt to design into the systems, various compensations for a lower standard of flight experience, including possible "safety" contraints that would prevent a less experienced pilot from making a mistake in judgement? Is this why the Airbus design philosophy "is the way it is"?

I know this is "reaching". You'd have to check out how Airbus markets their aircraft to the various airlines, and if pilot costs are a factor in that marketing. You'd also have to check out what kind of pressure Airbus, and maybe some of their airline customers, apply to the various civil aviation authorities to try and lower the pilot standards for experience.

All I know is that the FBW envelope protection system is subject to failure just like the autopilot is, and both should have a cutoff (or release) button if such an eventuality occurs, just as it did in the accident that started this thread.

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Safe flying to you...

[This message has been edited by Flight Safety (edited 15 June 2001).]
 
Old 15th Jun 2001, 23:37
  #115 (permalink)  
Frederic
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Flightsafety, Brad 737, I strongly disagree with your incorrect vision on the AI phylosophy. I do not see the pilot dissapearing from the cockpit at all in the future and I do certainly not feel or think it is Airbus' intention nor mine to do so. In fact, I think the Airbus FBW's lend themselves much better to manual flying. Actually, the current devellopement in avionics shows a willingness to make them more natural to use, and to allow the pilot more insight and so more imput into the situation. Stop seeing FBW as something that limits the pilot. I am a line pilot, and although maybe not being such a natural as Brad seems to be, I do believe strongly in the importance the pilot has in flying airliners. I think he should very much stay in control and I don't think FBW prevents him doing so. Ask any F-16 or Eurofighter pilot what they think about this... You are also forgetting that AI FBW IS overridable. You can switch of the FAC's or ELAC's or hold the trimwheel in position (you didn't hear me say that) to go into direct law and have a conventional aircraft in your hands. But it isn't designed to do so. This would be like having a car with an overridable antiskid. I can assure you that as an average driver, (not a superior one like Brad ;-) (only jokin' Brad, I know you didn't mean it that way) ) , the first thing you will do the day that kid jumps in front of your car and it LOOKS as if you're not going to make it, is push the "override button". The CHANCE of you hitting the kid because you disconnected the system will always be higher than if you didn't. Come on, Formula 1 drivers use active suspention and anti-skid braking. Are they inferior drivers, guys?? I bet my bottom dollar accidents WILL happen because of the electronics going wrong in one of these systems. What do you want to do? Do away with anti-skid??? I never doubted pilots are great decision makers, but they (I) do not have built in G and angle of attack meters. The final decision to roll the aircraft left or right or pull more or less G's should always be left with the pilot. But compare it with FADEC. The system is designed to give you the maximum it can get immediatly. And it does limit the pilot by giving him a limited amount of thrust. It will give you the maximum rated thrust of the engine, not what the engine might (???) be able to do. Why, Brad 737, would you know better how many G's you're pulling than how much EGT or N1 your engine has? Exactly, you need something to measure it with, then you need something to prevent you going over the limit because you know you will one day... The system never questions your decision making ability (you get max rated thrust when you ask for it), but it inevitably has the edge when providing you with max performance within the limits. One day there will be 1 (or God forbid) 2 FADECs going haywire and preventing a conventionally controlled aircraft from e.g. going around. That won't mean that FADEC is crap, or that the pilots should all of a sudden be allowed to get 1000C EGT from an engine that is rated to do 650 EGT. It does mean that a fault occured in the design of the system, wich is inevitable, no matter what kind of system you design. Be it hydraulic/direct, cable or FBW... Stop treating computers like ET's please. Computers are machines, they can and they will go wrong. And they don't posses some kind of personality or have a will of their own. They are systems that need to be develloped, just like all the other ones.

PS: without wanting to sound patronising, but can you please first READ my postings before criticising them?
 
Old 15th Jun 2001, 23:48
  #116 (permalink)  
metrodriver
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FS, non-us airlines have been putting low time fo's in airplanes even before somebody thought of putting color-tv's in the panel of big jets, no link there with the airbus, btw, us-airlines are doing it too as long as you're not a white male
 
Old 16th Jun 2001, 01:50
  #117 (permalink)  
AhhhVC813
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Anyhow, it is vitally important to have the ability to pull more than +30 deg & -15 deg in pitch, oh and 67 deg in roll (particularly for a barrel roll), oh yes and +2.5g/-1g (clean). It is also a requisite to be able to stall it, especially if you wish to enter a spin, plus a myriad of other exceptional manoeuvres that are utilised every day........
 
Old 16th Jun 2001, 02:40
  #118 (permalink)  
Flight Safety
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Metrodriver, what I was referring to is the FAA requirement for a minimum of 1500 hours to even get an ATPL. Not so under most other civil aviation authorities. I'm talking about 400 hour FOs, not the minimum 1500 hour FOs in US airliners.

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Safe flying to you...
 
Old 16th Jun 2001, 10:07
  #119 (permalink)  
Burger Thing
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A couple of years ago I saw a video of Amexxxxx Airlines. I believe it was the Chiefpilot that times who was making an interesting statement about investigations of accidents/incidents reports. He said, that especially pilots from Overseas (e.g. Europe) tend to rely in case of an emergency or system malfunction on automatic systems, rather than on flying skills. Maybe caused by a in general very uncritical attitude towards automatism.

That was not ment as a judgement, it was rather an observation. It is interesting to see, that it is even reflected here in this particular forum. I am from Europe, too...

And to Frederic and AhhhVC813: there have been cases, where pilots saved the day, by going beyond design limitations. I heard of a starlifter, which lost 2 engines while manouvering in the mountains of ex-yugoslavia. He overboosted the remaining engines. After landing he replied to the question, why he firewalled (and so ruined) 2 good engines, with '...because I couldn't forward them even further !' He obviously needed more than the maximum rated thrust of the engine, and the engine was able to do so - and saved his butt !

Another case was a TriStar, which had a stucked stabilizer, causing the ac going into a normally uncontrollable nose-up attitude. The pilot recovered by constantly banking the ac heavily to one side to another, to lower the lift component, until the situation was under control.

About Formula 1... Ask Coulthard and Hakkinen what they thought about their electronics when they were stucked on the grid-line a couple of times.....
 
Old 16th Jun 2001, 18:14
  #120 (permalink)  
Frederic
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Burger thing, thanks for reading my previous postings. Of course there are situations where going over the limits will save your butt. But 1: he would (might, I don't know?) have made it if he wouldn't have overtemped his engines. 2: If he would have pushed the engines further, at some point, he would have destroyed them. The fact that he COULDN'T push the engines any further saved his butt as much as the fact that MIGHT not have made it if he wouldn't have pushed them further than their rated limit...
BTW: ask Coulthart and Hakinnen what they would think of removing all the electronics and limit protections from their cars! Them being stuck at the start every now and then does not weigh of against the edge it provides them with when they do work. But I'm straying out of my field. The F1 was mearly an example to make a point. To all: Thanks for replying. Discussions like this stay fun if people (me included) are willing to open their minds and talk on a reasonable tone. Thanks again for making me think about stuff. Have to get on with my life now. CU
 

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