From kls Wed Dec 4 02:42:19 1996 Newsgroups: sci.aeronautics.airliners Path: bounce-back Date: 04 Dec 96 02:42:19 From: rdd@netcom.com (Robert Dorsett) Subject: Re: New ground proximity warning. References: Message-ID: Approved: kls@ohare.Chicago.COM Sender: kls@ohare.Chicago.COM Organization: Netcom Online Communications Services (408-241-9760 login: guest) In article faurecm@halcyon.com (C. Marin Faure) writes: >I had an opportunity to see an Alaska Airlines internal communication >video yesterday, and they described a new terrain avoidance system that I >think is pretty slick. It is being installed on their 737-400s and will >undoubtedly be a feature of their new 737s as well. > >A very accurate terrain map of an area-- in the example on the tape it was >Juneau, Alaska-- is put on a CD-ROM. Not to sound trite, but the reliability of such a system is directly related to the quality of data which goes into it. I can't help but think of the large number of "uncharted" swatches on every Cali crash chart I've seen thus far. And any cartographer is aware of the huge number of "design compromises" which go into map-making, and the amount of fudging (inter- polation between data points, etc) that goes on. For the purpose that you describe, "accuracy" does not seem to be hugely important--situational awareness is more important, and one can suffer significant deviations in the terrain model. If "accuracy" does start to assume a role in such systems--for navigationally relevant terrain avoidance--I'd start to become very concerned. We need to step away from the "gee whiz" aspect of this type of technology (which has apparently influenced at least one senior DOT bureaucrat to call for such devices) and harshly analyze the data set, its intended purpose, and logically analyze how the current system fails us. There are likely going to be solutions out there which are much less expensive (and less glamorous). -- Robert Dorsett Moderator, sci.aeronautics.simulation rdd@netcom.com aero-simulation@wilbur.pr.erau.edu ftp://wilbur.pr.erau.edu/pub/av