At 10:29 PM 1/4/99 -0500, you wrote:
.snip.
>
>Correct. NONE of the autopilot systems are date based/biased. Also the
>general design of aircraft systems is one of fail soft. Fail soft is
>simple fail to the least dangerous mode or disengage for manual override.
>So in the case of GPS with databases (maps) they fail such that you can
>only use the map for manual reference or emergency modes but the nav
>functions (whch way and all) are unaffected. Actually it's less a problem
>than that. Likely the ticketing systems or ground baggage handling are
>more suspect as they are not "safety of flight".
>
Not *entirely* true... There are date dependencies using GPS (for reference
see
http://www.laafb.af.mil/SMC/CZ/homepage/y2000/y2k/index.htm) that will
cause a "Y2K" of sorts - the week number for ephemeris (and other) info
"rolls over" every 20 years, and the first such rollover will be during
August of this year. The problem is expected to cause problems in some
receivers, perhaps causing erroneous output (unlikely) or possibly "loss of
acquisition" when the receiver decides to listen to the wrong constellation.
.snip
>
>All too true.
>Allison
Gary
Received on Tue Jan 05 1999 - 03:43:22 GMT