Revisiting the Aviation Safety vs. Networking discussion

Owen DeLong owen at delong.com
Mon Dec 28 14:38:28 CST 2009


On Dec 25, 2009, at 7:57 AM, Anton Kapela wrote:

> On Fri, Dec 25, 2009 at 5:44 AM, Vadim Antonov <avg at kotovnik.com> wrote:
> 
>> The ISP industry has a long way to go until it reaches the same level of
>> sophistication in handling problems as aviation has.
> 
> It seems that there's a logical fallacy floating around somewhere
> (networks have parts and are complicated, airplanes and flight involve
> lots of parts and are also complicated, therefore aircraft are like
> networks). I assert that comparing 'packet switching' to an industry
> that has its roots in the late 1800's and had its first "hello world"
> moment in 1903 isn't terribly fruitful.
> 
As someone with a fair amount of experience with both, I have to
disagree with you.  Yes, there are differences, and, yes you have
to keep comparisons and the like in perspective, but, there are
definitely areas where networking could learn from aviation, and,
to some extent, vice versa.

> Further, aircraft are the asymptotic limit of 'singly homed transit.'
> Because of this, I think one could argue that pilots and ATC must be
> held to a different professional standard due to the nature of public
> trust at risk.  At the other end of our strawman spectrum, we have end
> users who must accept the risk that their provider will be unable to
> connect them to lolcats.com on occasion, perhaps as often as 0.01% per
> year, and most are happy to accept this. Four nines survivability on
> flights, clearly, won't work.
> 
Correct... As I stated in my earliest posts on this subject, while there
is value to be obtained in looking at how aviation has improved its
safety/reliability record over the years, there is also value in recognizing
the cost/benefit ratio of some of those improvements.

If you draw a graph with one curve arcing from bottom left towards
upper right, steepening as it goes to the right, that line can be thought
of as the amount of cost of achieving additional reliability.

A second curve sloping from top left to bottom right, flattening out
as it goes to the right can be thought of as the gains achieved from
those additional 9s of reliability.

Finally, the point where those two curves intersect is defined by
the cost of outages and/or downtime.

Interestingly, this same diagram will be familiar to most pilots,
but, the two arcs will be induced drag (drag from producing lift)
and parasite drag (drag from friction with the air). The point where
they meet is called "L/D Max" and is the airspeed at which the
given aircraft will achieve it's best glide ratio.

> What I'm getting at is that after following this thread for a while,
> I'm not convinced any amount of process-borrowing is going to solve
> problems better, faster, or even avoid them in the first place. At
> best, our craft is 1/3rd as "old" (if that's somehow I measure of
> maturity) as flight and nobody is being sued to settle 200+ accidental
> deaths because of our mistakes.
> 
There are lessons to be learned that are valuable.  Both from
things aviation has done well that we could emulate, and, from
things aviation has done poorly that we should avoid.  There
are also additional lessons to be learned about the differences
in cost/benefit analysis between the two disciplines.

Owen





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