Re: FMS capability (was: Re: AA965 proves Airbus bashers deadly wrong)

From:         gorca!jnhall@uunet.uu.net (Joseph N. Hall)
Organization: GORCA Systems Inc.
Date:         15 Mar 96 01:05:25 
References:   1 2 3
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In article <airliners.1996.345@ohare.Chicago.COM> Tom Speer <speer%do.edw@mhs.elan.af.mil> writes:
>However, if you talk to the
>Defense Mapping Agency folks that put together the data, they will tell you
>that the data are NOT, repeat NOT, reliable enough to serve as the sole
>means of terrain avoidance.

My fiancee is a PhD candidate digital cartographer, and she can talk to
you at length about the obvious discrepancies found in the publicly
available elevation datasets.  Really, really blatant stuff, like missing
or gratuitous peaks.  My assumption is that if extremely accurate datasets
exist they are classified or in production.

Also, there are the storage requirements ... let's say CONUS is roughly
1500 x 3000 mi, sampled at 100ft intervals to a 16-bit accuracy ...
this means we need 4.5M x 52^2 x 16 bits = 22GB ... and how will all
that data be collected with verifiable accuracy?  Why not just turn on
the radar altimeter and watch out for blinking red lights.