keithl,
Well, normally, the marker is used for GS check or as FAF - so the "equivalent position" would be your DME range used for that purpose.
The advantage of using that position (operationally speaking) - is that it's a position already in use - if you've done your GS check, you continue, if GS check not performed yet, you discontinue the approach. So simple even uncle Empty can do it
If you choose to operate using 1000 ft. AAL - you have to figure outr a new altitude on the altimeter - altough I don't know if some operators performed their "stabilised approach´-cut-off at 1000 ft. AAL - most use either 1000 ft. RadAlt or baro minima +1000 ft. (to keep it simple). If your operator uses 1000 AAL for that purpose, well, might as well use that...
But - you delay your cut-off point (at most airports), thereby increasing the chance that you'll have to discontinue the approach i.s.o. going down to DA/H to take a look
- especially relevant in the circumstances described above.
To remain on thread - if you are carrying out an approach (JAR-OPS 1 operators, that is) and the RVR drops below approach minima (visual or otherwise) - your ops manual will prohibit you from continuing the approach. ATC (and through them, possibly, the CAA) will only be a circumstantial factor.
I think the reason why people focus on the ATC bit is that it seems much more powerfull when somebody speaks the words "You can't do that!" as opposed to knowing that the same words are written by your DFO in a book somewhere in the ships library
My 2 eurocents worth - brgds fm
Empty