Sender: <marv@lancaironline.net>
To: lml@lancaironline.net
Date: Thu, 20 Apr 2006 01:50:38 -0400
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From: "Tom Gourley" <tom.gourley@verizon.net>
Subject: Re: [LML] Re: Avionics:  Black Art or Science
Reply-to: "Tom Gourley" <tom.gourley@verizon.net>
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Someone once wrote, "Any sufficiently advanced technology is 
indistinguishable from magic."  Depending on your personal technology level 
some of this stuff, especially the things that can go wrong, seems like 
magic.  Heck, I'm an engineer and have spent a (depressingly) large amount 
of time in my career chasing down slippery problems.  (But then if it 
weren't for problems there would be an awful lot of unemployed engineers.) 
Of course, once you get the problem fixed and look back at how you arrived 
at the solution you invariably think, this should have been obvious!  Ah, 
the wonders of 20/20 hindsight.

Have fun chasing those electrons.

Tom Gourley

----- Original Message ----- 
From: "Marvin Kaye" <marv@lancaironline.net>
To: "Lancair Mailing List" <lml@lancaironline.net>
Sent: Wednesday, April 19, 2006 7:56 PM
Subject: [LML] Re: Avionics: Black Art or Science


> Posted for "Halle, John" <JJHALLE@stoel.com>:
>
>  Brent writes (below) that electrons follow rules that can (sooner or 
> later)
> be understood through the use of reason.  Reminds me of the story about 
> the
> lawyer who wrote a one-page legal document and sent a bill for $500 with a
> single item: "draft document: $500."  The client objected that it could 
> not
> have taken more than a half hour to write the document.  The lawyer sent 
> back
> a revised bill with two items: 1. "draft document: $50"; 2. "knowing what 
> to
> write: $450."
>  Having just finished replacing my panel, I must, at least superficially 
> agree
> with Brent.  The problem is that, as anyone who has ever looked at the 
> back of
> a modern instrument panel knows, there are electrons going through 
> hundreds of
> wires.  Some of them are carrying digital data (whether the electrons are
> analog or not) that may be AIRINC, RS232 or something else, some are 
> carrying
> a simple current that is used to power something; some are carrying a 
> current
> that is used to transmit data. A huge number of them are going to 
> something
> called "ground", a simple concept until you try to actually do it right. 
> They
> go to and from various boxes that have unbelievebly complex circuits 
> etched
> onto chips and other devices.  These boxes either do or don't talk to each
> other using protocols understood only by software engineers.  In theory we
> don't have to understand how all this works because all we have to do is
> follow the installation and setup directions, 100% of which are wrong or
> incomplete in some respect and many of which are almost totally wrong or
> incomplete.  If something is not working properly, there are usually at 
> least
> ten possible explanations that occur even to a non-engineer, to say 
> nothing of
> the fifty explanations that occur to engineers.  Each one of these
> explanations involves the assumption that electrons follow simple rules 
> that
> can be understood through the use of reason.  The black art is knowing 
> which
> explanation to investigate first.
>
> --
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