"Peter Duniho" wrote in message
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"Icebound" wrote in message
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Never having flown a VOR course myself... I still doubt very much that
any two pilots (OR auto-pilots), flying reciprocal headings between two
VORs, would both be able to *simultaneously* hold a course to within 10
feet of the centre-line for the whole course, considering the receiver
errors and that the VOR radial-signal *itself* probably varies more than
that.
I could be wrong.
You are wrong. 
For two pilots to *intentionally* stay exactly on course center on a VOR
airway would be challenging, granted. But the airway provides an
"attractor" for airplanes, and inasmuch as the airplanes average toward
the center of the airway, eventually a couple will come along flying the
exact same distance from the actual airway (whether that's 0.0 miles
off-center or 3.9 miles off-center).
Accepted and agreed. "eventually".
But in the GPS case, it is pretty much in "every" case that two aircraft
using those two waypoints will be pretty much in the center.