Re: Airbus safety

From: (Ken Hoyme)
Organization: Honeywell Systems & Research Center, Mpls. MN, USA.
Date:         16 Dec 92 14:00:45 PST
References:   1 2 3 4
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In article <airliners.1992.153@ohare.Chicago.COM> Robert Dorsett <> writes:

> The problem is that software is so much more easily changed than hardware, 
> that we could very well start an avionics equivalent of "creeping featurism."
> Changing the way a stick behaves can be done in just one firmware update: no 
> need to develop new tooling, production techniques, train assemblers and
> maintenance engineers, offer the retrofit during the next C check, etc.  
> Just the internal development process, which one can assume is faster and 
> cheaper than for hardware.  But, by virtue of this ease, it's also more 
> *unstable* than hardware-based solutions.

> Evidence to support this position?  The A320 has about 4M of code.  The A330/
> A340, 10M.  It's happening as we speak...  

> Do any Honeywell people reading know how big the 777 EFCS is going to be?

Well, this is an apples-to-oranges comparison.  I can only speak (and
only in vauge terms, of course) about the portion of the 777 that
Honeywell is producing.  Honeywell's Airplane Information Management
System (AIMS) contains the FMS function similar to previous generation
airplanes, but does not encompass the autopilot (Rockwell Collins) nor
the FBW Flight Controls (GEC).  The FMS alone requires about 2Mbytes of
executable code.  It also requires a Nav Data Base and RAM for
operation.  I do not know the complexity of the other components of the
"EFCS".  Of course, Displays could be considered another part of the
system.  That function lives in AIMS on the 777.