And that may be absolutely fine but GPS to the DME is not the same as DME distance. I am not trying to sell DME but it is potentially a significant distinction.
Peter, not sure what you mean, have to think about that. If the physical VOR/DME station is in the database then a direct to it should be precise ... but maybe I don't understand. At all airporst I have flown to it worked (but that's only 5 IFR airports in the Cirrus ;-))
The problem is that there are approaches, usually nonprecision ones I suspect but there could be ILS ones too, where the physical DME hardware is nowhere near where you think it is, but say a few miles behind the runway, and the transponder in there is rigged to return a zero reading (as displayed in the aircraft's DME) when you are at the MAP (or at whatever point they want your DME to read zero).
This might be because it is not convenient to place the DME hardware at the MAP.
In such cases, I very much doubt somebody at Jepp or Garmin will have gone to the trouble of creating a virtual waypoint which gives you the same GPS DCT distance.
In the KCHD case I recall, the DME distances are to a distant VOR and if you have two GPSs then you could set the 2nd one to "fly" a DCT to that VOR, and the distance reading thus obtained would do. That second GPS would be ignored in all other respects.
But that is not the same as the "offset DME" scenario I mention, where I am pretty sure there will not be an equivalent GPS waypoint.
Europe has no US-style GPS substitution rule for ADF etc.
What rule are you referring to, Peter?
Europe has no US-style GPS substitution rule for ADF etc.
Are you saying that EASA never addressed the subject of allowable substitutions of ground-based navigational aids with space-based navigational aids (as was done, most recently, by FAA in AC 90-108)?!
Or, are you saying that the Europeans specifically do not allow any substitutions of that kind?!
There are no rules (for private flight) on how equipment is to be used.
The rules are for equipment carriage only.
Europe has no rules (that I know of) for substituting [the carriage of] a GPS for an ADF or a DME like the USA has.
I am sure NCYankee will be here tonight kindly explaining the US position, but it seems to be widely known in general terms.
It is possible that Switzerland has something, because I found such a concession when I researched this c. 2006. But they are not in the EU so can do their own thing.
What people do in reality is another matter 
Using GPS to fly e.g. VOR approaches is far safer.
What one can't do is use GPS distance in place of DME distance, unless the database contains a waypoint specifically generated to be equivalent to the DME=0 point. I am not saying nobody has done this; I just haven't seen that sort of thing. For example for any runway with two ILSs (one each way) you would need two such waypoints.
Yesterday during IR check ride when executing ILS approach I lost LOC (probably some antenna connection problem) and was required to switch to NDB approach. In real life I would probably use GPS for executing this but legaly I had to use ADF.
Peter, now I understand! I did not even think about that possibility, thanks. Anyway, until now I fly them differently. I use the GPS for simulating the DME when I am on the initial approach (like "turn right at D4.0 xy VOR to intercept loc")... On finaly approach I check the altitudes when I overfly the FAF, OM .... I am not very experienced in this but i think this should be safe. ADF i don't use at all, except on IR checkrides, but since I have learned how unprecise those approaches can be I don't do them. All the airports I need/want to fly to have an ILS or I fly there in VMC
FAA's Advisory Circular No. 90-108. March 3rd, 2011
The "rules" for this type of "substitution" are far more restrictive in Australia.
CASA's Advisory 366/10, October 2010
Note para 8, 9 and 10. I believe "DME/GPS ARRIVAL" is a terminal procedure unique to Australia....
Here is an example of the Australian DME or GNSS Arrival Procedure:
DME or GNSS ARRIVAL PROCEDURE for YBBN
Since Brisbane Airport is a primary control area and there are several "better" procedures published for it, it is very unlikely that one would be asked to use a "crude" DME/GNSS let-down there. DME arrivals are commonly used during "the first attempt" to get into a remote outback airport with no "actual weather"....
I did not even think about that possibility, thanks.
And that exactly is my point. Too complicated, too much to go wrong. Yes, it can be done. But it requires individual research and a high level of understanding of the individual approach and how it is coded in the database. If you simply use the NDB position and the range from the NDB when the DME is zero-ranged at the threshold, and fly a perfect approach with a stable profile, you will end up half the runway length closer to the runway than you expect.
This won't kill you in flat terrain, but if you fly the procedures into Innsbruck, good luck!
On final approach I check the altitudes when I overfly the FAF, OM
If the approach is a ILS/DME approach, in many cases there is no OM, just an altitude/distance check, and also the FAF tends to be charted as DME distance. A half-mile difference is around 150ft, so you "fail" your check. Now what? Ooops, did not expect that, go around, into the hold, faff with charts for 10 minutes? Not a problem in good weather, but on a bad day that is the last thing you need.
