Re: over-automation with glass cockpits

From:         faurecm@halcyon.com (C. Marin Faure)
Organization: Northwest Nexus Inc.
Date:         04 Aug 96 16:44:57 
References:   1 2
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In article <airliners.1996.1528@ohare.Chicago.COM>, mikem727@aol.com
(MikeM727) wrote:

> In article <airliners.1996.1454@ohare.Chicago.COM>, Rob Tremblay
> <dfens@netaccess.on.ca> writes:
>
> >The Airbus has a safety feature that only allows a pilot to pull the
> >maximum g-limit of the airplane- no more. Why would you want to
> >overstress the airframe?
>
> What if a situation arises where the only way out requires overstressing
> the airplane?  This could be recovery from unusual attitudes, or evasive
> action to avoid traffic or terrain.  There have been accidents where the
> the airframe was overstressed in order to recover.  For certification, the
> airframe must withstand 150% of published G-limits without failure.
> Someday that extra 50% percent may be needed.  From what I've read, Airbus
> FBW doesn't give you that option, even in direct law.  I don't know about
> Boeing's FBW.

The Boeing control (cable or fly-by-whire) philosophy is to give the
pilots the ability to do anything they want with the airplane whenever
they want.  The system will warn them when they approach the limits of
approved operation, and it will make it difficult to exceed these limits
(higher stick pressures, loud horns, verbal alerts, flashing lights, etc.)
but the pilots of Boeing airplanes CAN exceed the limits if they deem it
is necessary to ensure the safety of the airplane.

C. Marin Faure
   author, Flying a Floatplane