Air France A330 - Missing over Atantic

flyingcheesehead said:
Right - But Alternate Law is supposedly less stable than the normal mode. Seems backwards.
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Sigh, you can only build in so much redundancy. If you have multiple failures eventually you must either completely fail or degrade.

There is no single computer failure that will take the airplane out of normal law. But upon *MULTIPLE* failures it *HAS* to degrade, in this case, it degrades to alternate law.

Basically, don't get worked up over some stupid news article talking about being in a less stable mode. The truth is that MANY failures will CAUSE it to degrade and it STILL does pretty damn good.

Read this Kent:
http://www.airbusdriver.net/airbus_fltlaws.htm

Airbus builds a pretty decent product.
 
flyingcheesehead said:
What confuses me is this "alternate law" thing.

You're flying along, accidentally go into a thunderstorm, get severely bumped around and struck by lightning - And the airplane makes itself LESS stable? :hairraise:
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No. There are three levels of automation on the airbusses. Normal law, which everything works as advertised. Alternate law, in which the computers work in a slightly degraded mode, which in fact, IIRC, is just like any other airplane out there, including Boeing, in which the pilot has full control over the airplane, except certain protections such as over bank and over pitch, are inhibited, and one other layer which I can't recall the name of right now, in which there are no automated protections at all. In fact, that may be manual reversion in which the only thing controlling is the elevator and rudder, but don't hold me to that, it has been too long.

Alternate law lets the pilot control the airplane just like a pilot would control a 737 or 727. No more no less.
 
flyingcheesehead said:
Very interesting.

I still don't like it. Though it would have probably saved Colgan 3407, I'd rather have a good pilot flying an airplane that does exactly what he tells it to and nothing else.
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That is EXACTLY what Alternate Law allows.
 
Greg Bockelman said:
As usual, a lot of utter BS and Rampant speculation.

Sigh.:mad2:
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But nobody's posted the one yet about where this was a midair with an unmarked drugrunner flying a GIII or GIV to Africa across that corridor.... :rolleyes::devil:

Greg Bockelman said:
In fact, that may be manual reversion in which the only thing controlling is the elevator and rudder, but don't hold me to that, it has been too long.
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IIRC, the manual reversion is through use of rudder and elevator trim, but I may be wrong.
 
I posted the definitions of each state earlier in this thread for people.

Normal law, Alternate law, and direct law are the three laws before manual revision.

Despite some people's perception, some people do research before being smacked down by the almighty airline pilots.
 
From the wires...

AP said:
Bodies have been found from the crash of an Air France plane that disappeared Monday, the Brazilian air force says.
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Cheers,

-Andrew
 
flyingcheesehead said:
What confuses me is this "alternate law" thing.

You're flying along, accidentally go into a thunderstorm, get severely bumped around and struck by lightning - And the airplane makes itself LESS stable? :hairraise:
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As a control system designer, the more I know about how a dynamic system is performing, the better I can control it.

Lets do a simple example:

I want to control the temperature in the shower. But, there is a delay from the time I turn the knob to the time that the temperature water splashing on one's butt changes.

If I know the time delay, I can design a control law that changes the knob, waits the appropriate time and then make another adjustment. I get it right and you have a nice shower.

Simple, eh?

Suppose I get the delay time wrong (perhaps the shower head has been relocated, or my temperature sensor has moved). I make a control move, wait, nothing happens, move again, nothing happens, move again and finally the results of the first change finally arrive - OK, I do nothing. But now the results of the second change shows up and I say "oops - too hot" and I make a control move. The results of the third change arrive and I say "ouch ouch ouch!!!" and make a big control move - guess what is going to happen in a few moments... I go into a freeze / burn cycle.

My control law has now made things worse because the system is not responding as I expect.

​
Apply this to the Airbus - if everything is working OK, I can design a nice control system that will compensate for everything, add stability, and take a lot of the "feedback" load off the pilots hands. But, if things go to doo-doo and I can't rely on the information from the sensors I have to resort to less aggressive, less capable control laws to avoid making things worse and hope that the pilot has the information / ability to keep the airplane in the air (what other choice is there?).


​
 
N801BH said:
So far I cannot find a single Boeing, McDonald Dougless or any other manufacturer of transport aircraft who has suffered a failure. Anyone out there who remembers one ??
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Given that it is D-Day, I thought it appropriate to post this picture of Boeing VSTAB damage.... and they flew it home. :yikes:

-Skip
 

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French and Brazilian officials have described a "burst" of messages from Flight 447 just before it disappeared.

A more complete chronology was published Wednesday by Brazil's O Estado de S. Paulo newspaper, citing an unidentified Air France source, and confirmed to The Associated Press by an aviation industry source with knowledge of the investigation:

_ 11 p.m. local time — The pilot sends a manual signal saying the jet was flying through CBs — towering cumulo-nimulus thunderheads.

_ 11:10 p.m. — A cascade of automatic messages indicate trouble: The autopilot had disengaged, stabilizing controls were damaged, flight systems deteriorated.

_ 11:13 p.m. — Messages report more problems: The system that monitors speed, altitude and direction failed. The main flight computer and wing spoilers failed.

_ 11:14 p.m. — The final message indicates a loss of cabin pressure and complete system failure — catastrophic events in a plane that was likely already plunging toward the ocean
 
So, here I am laying in bed, getting ready to get some OJ and CNN is showing a almost complete and amazingly undamaged verticle stabilizer being towed back to shore. God this looks just like the NYC airbus incident all over again... Say it ain't so.....:eek::yikes:
 
Agreed. If we ever know what happened, I would not be terribly surprised to find it was structural failure of wings or horizontal stab, in conditions well beyond the expectations of any designers.
 
Greg Bockelman said:
As usual, a lot of utter BS and Rampant speculation.

Sigh.:mad2:
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This is probably a bad example to use in that none of us are likely to be in the situation of flying through crappy weather over the ocean, but I've gotta say it:

Is speculation so wrong? It allows us to put ourselves in that situation (whether we know what happened or not) and throw out some alternatives, have them shot down or affirmed, and learn something in the process, not to mention being more mentally prepared if we actually do end up in that situation.

Paul Bertorelli seems to agree: http://www.avweb.com/blogs/insider/AvWebInsider_CrashSpeculation_200562-1.html

Really, though, in this case I think The Onion nailed it (as usual): Investigators Determine Air France Disaster Caused By Plane Crash :rofl: (This isn't on their web site yet, but it's in the paper copy I picked up tonight)
 
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flyingcheesehead said:
Is speculation so wrong? It allows us to put ourselves in that situation (whether we know what happened or not) and throw out some alternatives, have them shot down or affirmed, and learn something in the process, not to mention being more mentally prepared if we actually do end up in that situation.
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The problem with speculation is not for us. We probably benefit from it. We're also smarter than the average idiot out there.

The average idiot is the problem. Said people take speculation as fact, and then ignore the findings when investigation shows what really happened. Said people then spread the speculation as fact to others, and we wonder why aviation has a bad reputation. The media feeds on speculation, because its goal is ratings and money, not reporting the news. So the more horrifying the speculation the better, facts be damned.

When we speculate amongst ourselves, we probably learn something. When others hear it, it hurts us since they'll take the worst possible scenario and run with it.

Really, though, in this case I think The Onion nailed it (as usual): Investigators Determine Air France Disaster Caused By Plane Crash :rofl: (This isn't on their web site yet, but it's in the paper copy I picked up tonight)
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Now THAT is a headline I can agree with! :rofl:
 
Ted DuPuis said:
The problem with speculation is not for us. We probably benefit from it. We're also smarter than the average idiot out there.

The average idiot is the problem. Said people take speculation as fact, and then ignore the findings when investigation shows what really happened. Said people then spread the speculation as fact to others, and we wonder why aviation has a bad reputation. The media feeds on speculation, because its goal is ratings and money, not reporting the news. So the more horrifying the speculation the better, facts be damned.

When we speculate amongst ourselves, we probably learn something. When others hear it, it hurts us since they'll take the worst possible scenario and run with it.
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Yeah, it sure would be nice if we had a place to speculate that wasn't open to the general public so we could do it without the potential damage to the industry... :rolleyes:
 
flyingcheesehead said:
Yeah, it sure would be nice if we had a place to speculate that wasn't open to the general public so we could do it without the potential damage to the industry... :rolleyes:
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Jason Miller from The Finer Points did an excellent episode about the Colgan crash a few months ago. They first talked a bit about why speculation can be useful and how speculation should happen.

There's nothing wrong with speculation; I've always said that. It does become an issue when the news media use speculation to boost their ratings.

-Felix
 
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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There you go again, bringing logic, and facts, and all that crud into the discussion...
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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SCCutler said:
There you go again, bringing logic, and facts, and all that crud into the discussion...
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I hate it when that happens.

Speaking strictly for myself, I find Greg's posts to be pretty enlightening, and I appreciate when he makes them.
 
tonycondon said:
im still pretty sure it was aliens.
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LOL, Tony......area 52 now?

I think it was N.Korea try'n to shoot a missile at Hawaii and missed.:D


All joke'n aside, ya gotta speculate to open your mind to different possibilities. Anyone that says something "cannot happen" doesn't have an open mind, kids, or employees.:smilewinkgrin::rofl::rofl::rofl: Ok, I can't put joke'n aside.:D
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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Well, speculation with ignorance is nothing unusual, or even necessarily evil. That's basically the scientific method. Make a postulation or hypothesis and see how well it matches with reality. I agree, however, that ignoring factual evidence that you've brought to the table via your posts would be very frustrating. That changes it from my scientific method analogy.
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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Greg,

Your input is valuable - I think that in some cases you're not being "ignored," just questioned because most of us don't understand a lot of the things that you do. Like, say, Alternate Law. ;)
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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Couldn't agree more Greg. Sadly, that's just how the news media, and to a lesser extend this forum (that's what ignore is for!) operate.
 
sba55 said:
Couldn't agree more Greg. Sadly, that's just how the news media, and to a lesser extend this forum (that's what ignore is for!) operate.
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Assume'n this is aimed at me?
 
Pure speculation (as if anything else was available)... My guess, the pitot issue cause a speed issue which allowed the plane to exceed its allowable Mach values and the plane came apart, just like they did before we knew about Mach....
 
Greg Bockelman said:
Actually my problem with speculation is that it is usually based on either ignorance or absolutely no factual basis to back it up. It kind of irritates me when I either get ignored or otherwise knocked down when I explain why certain things cannot happen.
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Is that why you're upset about speculation??? Forget that stuff, Greg. Those of us with brains know that you've got a lot more insight into this stuff than the average Joe. I, for one, am happy to have you chime in.

I think these discussions are helpful, at least they are for me. Lots of different angles are raised, and I always learn something I didn't know before.
 
flyersfan31 said:
Lots of different angles are raised, and I always learn something I didn't know before.
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I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
 
Everskyward said:
I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
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Agreed. Speculation and discussions about what went wrong in any accident can and should be completely separate from the blame game.
 
Everskyward said:
I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
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Aha -- yes, that, I agree with.
 
Everskyward said:
I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
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gismo said:
Agreed. Speculation and discussions about what went wrong in any accident can and should be completely separate from the blame game.
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Completely agree as well. Speculation can also lead into different directions and discussions perhaps not directly related to the accident in question.

Then there are postulations and scenario investigations where ideas can be put forth that may change the outcome in a situation. These type of conversations then change the conversation from 'what happened' based review to on that is a 'what if' discussion. 'What if' discussions are something that those of us involved in design are more comfortable. We tend to go into abstract reviews fairly easy. I have noted that those who are more into real life operations tend to shy away from that discussion and are more comfortable in the 'what happened' realm.

The example of this is that one type of thinking is that a+b = c and another is that I have a+b but if I also had d I could get a result of e. So then how do I redesign my system to be able to get d such that I can now change the outcome.
 
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Everskyward said:
I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
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And that's a very important thing to understand. Just because we do something a bit risky one time and don't get killed, doesn't mean it's guaranteed to work the next time. I think that such things lead to complacency, and the guy that gets killed doing something more dangerous than normal has probably done that same thing before.
 
Everskyward said:
I've heard that called "incidental learning" and I think it's helpful too. The part I don't like about speculation is people sometimes crucify the pilot before all the facts are in. Even if it ends up being 100% the pilot's fault it's still probably something that could happen to any of us. Most of us have gotten away with things that on a different day could have had a different outcome.
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True, but if it got me killed, I'd expect a "Dumbass" since I earned it. I own my mistakes, no problem.
 
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