"Icebound" wrote in message ...
So the question is: If my Westbound Cessna at 6000 feet (with the autopilot
keeping it happily on the GPS-track centerline) meets the descending Bonanza
on the reciprocal track between the same two airports (using a similar
GPS/a-p combo), there is a distinct possibility that the horizontal
clearance may be zero...

...so is there anything in the current crop of GPS and/or Autopilot systems
that allow me to maintain a small cross-track error of my choosing, without
actually entering off-navaid-off-airport waypoints? ...or do we care; am I
overly concerned???

As others have pointed out, the GNS 480/CNX 80 does allow a
cross-track error. I did want to make one small philosophical
point...here in the deep south, we generally get direct routing. If
you have the capability, and you ask for the direct routing, you
generally are increasing your safety (by an admittedly tiny amount).
Further, anyone who is flying VFR and uses the airways is also
increasing his/her risk by that same small amount.

I do doubt that ATC will descend you through another aircraft on the
same airway, so the chances of meeting an IFR aircraft is
diminishingly small, but your concern is most likely regarding the VFR
aircraft sharing the airway.

Hence this discussion is of the "how many angels can dance on the head
of a pin" sort...making it perfect for USENET. And the take-home
points are(IMO) fly direct whenever allowed. Generate your courseline
from some NON-standard point. That is, don't go direct from some
intersection or from the runway...go from some offset point...avoiding
the other guy (most likely VFR) doing the same thing from your
destination. Don't use airways unless you must. And when you fly the
Atlantic (in a non-radar environment)...or the non-radar environments
of the USA...use SLOP!

Jim