Peter wrote:



However, I've heard from an American pilot that all the overlay
approaches in the USA work just the same as the full GPS approaches,
in terms of GPS behaviour, auto sensitivity switching, etc.

Is this true?

Only where authorized by the FAA; i.e. "VOR or GPS Runway 36."

That translates to the approach being in the database with approach
sensitivity and RAIM available for the final approach segment.

If the approach doesn't have "or GPS" in the title; e.g, "VOR Runway 18"
the avionics vendor can still elect to have the approach in the database
but it cannot invoke approach senesitivity nor RAIM for the final
approach segment. In other words, it would be advisory only and only
"additional pilot information" to the VOR approach terminal routes and
final approach segment.


If so, it would indicate that Jepp have given non-US overlay
approaches a lower status as far as the GPS operation is concerned.