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Search: Posts Made By: CogSim
Showing results 1 to 35 of 46
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Forum: Tech Log
27th May 2011, 02:42
Replies: 2,546
Views: 936,026
Posted By CogSim

I understand your frustration. I'm only...

I understand your frustration. I'm only speculating like Taleb, that may be human beings are not good at predicting/dealing with the kinds of nonlinear failure modes exhibited by digital systems.

...
Forum: Tech Log
27th May 2011, 01:44
Replies: 2,546
Views: 936,026
Posted By CogSim

Nonlinearity

Preface: We don't know if FBW played any part in the chain of events. We don't know if crew response played any part in the chain of events. We'll hopefully know by tomorrow.

The comments below...
Forum: Tech Log
26th May 2011, 23:57
Replies: 2,546
Views: 936,026
Posted By CogSim

Yes, I failed to understand this assertion by...

Yes, I failed to understand this assertion by BEA. Is it possible to have conditions that on the one hand overcome pitot heat to clog them up, but OTOH, don't accrete ice anywhere else? I'm not...
Forum: Tech Log
26th May 2011, 23:13
Replies: 2,546
Views: 936,026
Posted By CogSim

JD-EE, That was kind of the point. We...

JD-EE,



That was kind of the point. We think that there is more than a good chance that the pitots iced. In our discussions we are isolating the problem. We are implicitly assuming an otherwise...
Forum: Tech Log
26th May 2011, 23:03
Replies: 2,546
Views: 936,026
Posted By CogSim

You've hit the nail on the head. IMO, the goal...

You've hit the nail on the head. IMO, the goal should not be to "eliminate" pitot ice. This may be all but unattainable. The goal has got to be a graceful degradation of the system if pitot ice...
Forum: Tech Log
26th May 2011, 22:47
Replies: 2,546
Views: 936,026
Posted By CogSim

Without context its difficult to say. If we were...

Without context its difficult to say. If we were to only look at the four words presented, not knowing what preceded or followed, I'd "transform" this as "I don't get it!!". This sounds more like a...
Forum: Tech Log
26th May 2011, 17:04
Replies: 2,546
Views: 936,026
Posted By CogSim

Neither am I. My point is that this is the...

Neither am I. My point is that this is the dilemma we face, like it or not. Its an all or nothing deal. So you are completely ignorant or completely "in control" as the poor crew of 447 found out.
Forum: Tech Log
26th May 2011, 16:22
Replies: 2,546
Views: 936,026
Posted By CogSim

I never quite understood why this has to be a...

I never quite understood why this has to be a choice. It seems to me that future systems will need to seriously consider a solution where the pilot and the computer work together if we need to see...
Forum: Tech Log
26th May 2011, 06:05
Replies: 2,546
Views: 936,026
Posted By CogSim

From this NASA tutorial...

From this NASA tutorial (http://aircrafticing.grc.nasa.gov/courses/inflight_icing/main.html):

http://img13.imageshack.us/img13/5715/ice1n.gif
http://img218.imageshack.us/img218/4587/ice2u.gif...
Forum: Tech Log
26th May 2011, 03:27
Replies: 2,546
Views: 936,026
Posted By CogSim

Thanks for the post bear. You also...

Thanks for the post bear.



You also raised a valid point vis-a-vis the statistical credibility of such a design. Placing confidence in the divergence as you put it. (sorry to keep quoting the...
Forum: Tech Log
26th May 2011, 01:43
Replies: 2,546
Views: 936,026
Posted By CogSim

I agree with this point. Still, whenever I...

I agree with this point.

Still, whenever I hear this, it makes me squirm. As the pilots among us know, sometimes its easier said than done. It's important to keep that in mind come Friday.
...
Forum: Tech Log
26th May 2011, 01:02
Replies: 2,546
Views: 936,026
Posted By CogSim

bearfoil: request to reinstate

Dear bearfoil,

I'm writing to officially request you to reinstate your post re Anomalous Design.

Sincerely yours,
Cog :)
Forum: Tech Log
26th May 2011, 00:51
Replies: 2,546
Views: 936,026
Posted By CogSim

bearfoil

There was an intermittent post from bearfoil that seems to have disappeared. There were some important points about how Anomalous Design works. I just wanted to add that in the scenario I envisioned...
Forum: Tech Log
25th May 2011, 23:03
Replies: 2,546
Views: 936,026
Posted By CogSim

leave the pitots alone... arright? ;)

With all due respect to the brilliant minds on this forum who have been discussing alternate solutions for the pitot issue and without sounding insensitive to the families and friends of those lost...
Forum: Tech Log
25th May 2011, 21:37
Replies: 2,546
Views: 936,026
Posted By CogSim

pitot heat

Here's a simple idea. Apply different heat settings to the three pitot probes. In the event of all 3 probes icing up, at least this could ensure an asymmetrical failure. This seems to be a more...
Forum: Tech Log
24th May 2011, 19:46
Replies: 2,546
Views: 936,026
Posted By CogSim

Difficult to know. All depends on the nature of...

Difficult to know. All depends on the nature of icing/ice accrual, which we may never fully know/understand. My guess would be that the crew may have known for some time before AP disconnect that...
Forum: Tech Log
24th May 2011, 17:24
Replies: 2,546
Views: 936,026
Posted By CogSim

When everything is said and done, if the root...

When everything is said and done, if the root cause points beyond a doubt to crew action or lack thereof, the approach taken will be, "if it ain't broken, don't fix it". The most recent AIT from...
Forum: Tech Log
24th May 2011, 01:31
Replies: 2,546
Views: 936,026
Posted By CogSim

No harm. I possibly didn't phrase my thoughts too...

No harm. I possibly didn't phrase my thoughts too well. I am convinced that with training and experience, the position of sidestick will make very little difference, if any, in the vast majority of...
Forum: Tech Log
23rd May 2011, 21:02
Replies: 2,546
Views: 936,026
Posted By CogSim

PM is a euphemism. And whats the PF doing anyway?...

PM is a euphemism. And whats the PF doing anyway?

This raises interesting questions about experience. What does it mean to have 10,000 hrs of experience if 7,500 or more of that time was spent...
Forum: Tech Log
23rd May 2011, 19:37
Replies: 2,546
Views: 936,026
Posted By CogSim

OTOH the post is about mission critical software....

OTOH the post is about mission critical software. I don't see why, say, the inflight entertainment system code needs to be "ultrareliable". If someone in the know can comment on the control logic...
Forum: Tech Log
23rd May 2011, 18:47
Replies: 2,546
Views: 936,026
Posted By CogSim

The author claims A320 in 1988 (a quarter century...

The author claims A320 in 1988 (a quarter century ago) had 60,000 lines of code. And since then the size has increased by two orders of magnitude. So a comparable a/c today has 6 million lines of...
Forum: Tech Log
23rd May 2011, 18:33
Replies: 2,546
Views: 936,026
Posted By CogSim

6 million lines of code in A320 class a/c !!!...

6 million lines of code in A320 class a/c !!! :eek:
Forum: Tech Log
23rd May 2011, 17:53
Replies: 2,546
Views: 936,026
Posted By CogSim

I've never flown a/c with control wheel, so can't...

I've never flown a/c with control wheel, so can't comment on the ergonomics. Sorry. But presumably, the control wheel is also designed for two handed control unlike the sidestick. I don't intend to...
Forum: Tech Log
23rd May 2011, 17:26
Replies: 2,546
Views: 936,026
Posted By CogSim

sidestick

I have always wondered about the position of the sidestick. This of course is one of the other differences to keep in mind when comparing F-16 type HOTAS and Airbus sidestick. When I first started...
Forum: Tech Log
22nd May 2011, 22:57
Replies: 2,546
Views: 936,026
Posted By CogSim

stick technique

Chris Scott's notes on sidestick technique are worth a read even for non-FBW pilots.
Forum: Tech Log
22nd May 2011, 17:04
Replies: 2,546
Views: 936,026
Posted By CogSim

Good point. If true, would mean a breakdown of...

Good point. If true, would mean a breakdown of CRM. OTOH, how could the capt. enter through the secured cockpit door unless the situation took minutes to unfold. On the whole, I'll pass on this...
Forum: Tech Log
22nd May 2011, 02:48
Replies: 2,546
Views: 936,026
Posted By CogSim

UAS->ALTN2->LOSA(loss of situational...

UAS->ALTN2->LOSA(loss of situational awareness)->LOC1->Recovery?->LOC2?->Recovery?->EOFLT(end of flight)

seems to be the simplest chain without invoking gremlins.
Forum: Tech Log
20th May 2011, 20:24
Replies: 2,546
Views: 936,026
Posted By CogSim

To be specific, we are trying to push the...

To be specific, we are trying to push the envelope. :cool:
Forum: Tech Log
20th May 2011, 16:08
Replies: 2,546
Views: 936,026
Posted By CogSim

As someone pointed out earlier. Don't hurry but...

As someone pointed out earlier. Don't hurry but lose no time. This is what training is supposed to inculcate in you. If you look at the Hudson ditching you can't find a boundary between thinking and...
Forum: Tech Log
19th May 2011, 21:01
Replies: 2,546
Views: 936,026
Posted By CogSim

I agree. However, the reliance on training and...

I agree. However, the reliance on training and instrumentation comes from the realization that your "instincts" can fool you, and do so surreptitiously.

If you are interested,

"Appendix D....
Forum: Tech Log
19th May 2011, 20:31
Replies: 2,546
Views: 936,026
Posted By CogSim

location

I know I've been lost under the sea trying to get answers about how such a tragedy could have happened. At least that's the way I took it. YMMV.

When I read instinct, I'm reminded of what Wolfgang...
Forum: Tech Log
19th May 2011, 19:14
Replies: 2,546
Views: 936,026
Posted By CogSim

tubby linton

Location: Lost under the sea

If it wasn't so poignant, it would be funny :)
Forum: Tech Log
19th May 2011, 18:43
Replies: 2,546
Views: 936,026
Posted By CogSim

In my view, the whole case for what the computers...

In my view, the whole case for what the computers can do with regard to stability is overstated. Even computers can't make rocks fly. The aerodynamic form of the a/c no matter how inefficient demands...
Forum: Tech Log
19th May 2011, 08:44
Replies: 2,546
Views: 936,026
Posted By CogSim

Thats a lot of failure modes to contend with. ...

Thats a lot of failure modes to contend with.

On the one hand, the pitch up might have been a sincere attempt to protect the airframe. The control system can't query the airframe directly for its...
Forum: Tech Log
19th May 2011, 05:24
Replies: 2,546
Views: 936,026
Posted By CogSim

If I understand this statement as meaning that...

If I understand this statement as meaning that human in the loop leads to unpredictability, I agree with you. However, unpredictability doesn't always imply unreliability. It may be possible to...
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