Geoffrers, no we use it over the land but remember PAN-OPS approach design criteria does not allow for significant terrain or obstacles on the FAT. a combination of descent, coupled with the margin described should preclude inappropriate aural warnings.
It works fine generally but I guess you could argue that a ship on a non-CDFA non precision approach could experience an aural warning if they descend to MDA very early but in EU-OPS land most of us are not doing this any more and following the the CDFA concept.
DB