GPS substitution for navaids - Europe generally - is it allowed? (and low vis ops)

Indeed and this is dangerous because people substituting DME with GPS often do not understand that a DME can have a “virtual” location whereas the GPS substitution will point to its physical location. See the “DME I-LDY zero ranged to THR RWY 21”.

Jeppesen:

I do understand it, but:

- it is almost never the case
- it is irrelevant when you have your precise position on the ILS on the MFD for altitude checks
- the offset is marginal in most cases

Airborne_Again wrote:

That list is not exhaustive.

The list is exhaustive with respect to what is in EAD. I never claimed EAD is particularly complete

With DMEs used for ILS, there’s either a note (like here, “DME I-LDY zero ranged to THR RWY21”), or you can infer it from the distance scale

- it is almost never the case

You can die only once so I guess it’s relevant.

- it is irrelevant when you have your precise position on the ILS on the MFD for altitude checks

Altitude checks are related to DME distance.

- the offset is marginal in most cases

Except when it isn’t.

I actually think it is important and like having DME when flying an ILS. The offset can be critical. In fact I like DME when flying a GPS approach as it helps with situational awareness.

An ADF is just a waste of useful load, but DME is not IMHO.

Emir wrote:

Except when it isn’t.

But a quick glance at the approach chart should reveal whether it is. Looking at the approach chart is always a good idea anyway

- The exceptions are explicitely mentioned on the Jeppesen charts

- If the altitude check is at the OM and i have my position depicted on the Approach chart, then i don’t see much risk

I do agree that one has to be careful with these things, but i am sure that with most ILS’s GPS for DME is fine

Without DME the RNAV/GPS approaches to these rwys are probably safer.

I don’t think that document could be any clearer?

For Enroute navigation and on non-RNAV route based on DME, use of GNSS distance in lieu of DME distance is authorised within Metropolitan France Flight Information Regions.

For Terminal and approach area and due to the large amount of procedures based on DME, to the difficulty to substitute DME distance by GNSS distance and to the different regulations referenced in the previous sections, in practical terms, DME equipment is necessary for all IFR flight conducted within Metropolitan France Flight Information Regions.

I can do without the ADF but would not want to fly without DME.