Re: Boeing 777 - Totally Irresponsible?

Date:         27 Dec 96 13:32:19 
From:         s_odle@earthlink.net (Scott Odle)
Organization: Earthlink Network, Inc.
References:   1
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In article <airliners.1996.2792@ohare.Chicago.COM>, bgracy@worldnet.att.net
says...
>
>The keynote speaker of the 1996 Pacific Northwest Software Quality
>Conference reviewed the 10^9 (ten to the ninth power) problem.  Years of
>testing a PC program are required to believe that it won't fail within a
>week of release.  To meet the FAA standard of 10^9 hours of failure free
>operation would require 100 years of testing assuming that one could
>execute 1 test/sec (there are about 10^7 seconds in a work-year).
>
>He went on to say that because of the millions of lines of code written
>for the 777 that it would be impossible to test all of the failure
>conditions, and therefore was irresponsible to design and deploy such an
>aircraft.  He vowed never to fly on one...
>
>How was the 777 tested?  Is it safe?  Or is it "unsafe at any airspeed?"
>

It is not as simple as you make it sound.  First of all, all failures are not
required to be 10-9. Only those that are deemed "catastophic".  Determination
of failures is not necessarily done by testing.  Hazard analysis and effects
analysis is done to determine the effects of a given failure.  As for software,
there are very strict requirements.  However, the level that the software is
certified to based on if the a particular piece of equipment is critical,
essential, or non-essential.