On Mar 9, 8:54*pm, Padraig wrote:
But that is also defined by time from FAF for the LOC, right? *The
owner of the aircraft I tend to rent doesn't pay to keep his GPS
database up to date, so /U doesn't work too well in a lot of places.

I would think time would be part of it.

Good headwind down the ILS and your time now has changed since timing
is based on GS. Distance would be the constant that would confirm you
have reached the middle marker (along with the marker beacon) should
your actual time differ then what the chart projects on a no wind
situation.

ILS would be ground based, GPS would be informational only for DME
purposes. I would load the approach in the GPS and accept the warning
that it's for situational awareness as long as all the fixes matches
what I have on paper. This is how I would run my shop if I was to do
the approach.