"Overlay Approach" in the sense the FAA uses it is different from the "approach representation" that you have in your KLN94. An overlay approach is a new approach that has the same track as the underlying approach (so is quick to define and needs no survey) but has all of the key points defined in the database (IAFs, stepdowns, etc) so you can fly it with the GPS providing your only guidance.

I wonder if Jepp have done reasonably complete overlay representations for Europe. Perhaps somebody with a GNS530 can check a few.

Yes they have. I have flown the NDB overlays from the database hundreds of times. They are complete and work fine even on AP.

The 430/530 approach representations are generally pretty good - BUT in the UK they are still not "Overlay Approaches" in the sense they exist in the USA. For example (from memory) mine going into Shoreham doesn't have the various step down fixes as waypoints so you would still "need" the DME to give you this information. In a true Overlay Approach these waypoints would be in the database.

If it's an authorised overlay approach, the Jepp chart will have a waypoint reference printed next to each waypoint. For example, the initial fix will have something like IF06 next to it which will correspond with a fix in the database of the R NAV equipment you are using. Of course, you sbould chect the tracks and distances or Lat/Longs of each waypoint in the database from the chart before flying the approach.

mm_flynn confirms what I suspected; the UK overlays are only partial.

They are flyable OK but not as GPS approaches; one needs to use a DME also.

I've tried to track down references for the dropping of the ADF requirement on the CAA site. But can only find this!!

http://www.caa.co.uk/docs/33/FOD200004.PDF