Um, OK, I'm thick. I don't get what substitution rule I'm still
missing? With either approach you're using the VOR head for lateral
guidance and reading the distance from some fix in the GPS database
from the GPS head. Even the example approach used for how to do a DME
ARC in the KLN 94 GPS manual is an VOR/DME approach using an arc.

I guess the idea is that your position "on track" and "along track" need
differing amounts of, for lack of a better word, attention. You are
pointed along track and will cover all the along-track positions. You
want to remain on track, and not left or right of track.

For a regular VOR approach, it is the VOR that keeps you on track. DME
just reports your "along track" progress. For a DME arc it's the
reverse. You stay "on track" referring to the DME, and the VOR just
reports your "along track" progress.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.