Is there an airport with a DME/DME Approach?

i believe there are none, since DME DME would not provide heading guidance. the DME is usually used to estimate the range from/to DME beacon, which works at its optimum /fastest change in numbers/ when flying direct to, or direct from. using the other DME to estimate the sidewards drift from approach path would be tricky because of the circular feature of that readout - when you would fly straight, the value of distance from a fixed point would be changing. that would not be efficient and safe way to maintain the glide path.

to sum it up, the DME usually supplements distance information otherwise provided by ATC. this distance is then used for verifying the proper altitude - according to the bottom right box in the approach charts in the AIP publication.

more than that in principle the two distances would "draw" two circles, whose crossings are TWO. in the 3D space, with two hemispheres of equidistant points, their crossings would provide a curve of similar values /i.e. distance a to one DME, distance b to another/ that would not enable navigation.

-->two values of distance from two various ground based devices do not specify a point, but a curvature.

John B> how could a device with readout error of 0,1NM produce positioning more precise than a GPS, MLS or ILS ? wonder how. now IF (sic) the two are used to backup position calculating of another device, it is not DME/DME navigation.

Standing alone, the two DME devices CANNOT give a reliable position readout.

talk about the blended position a bit more... all the radar vectoring through common radar information is done with blended positions, with several "target" positions recalculated into one supposedly correct position.

No such thing as a DME approach, as already pointed out. DME is simply a component of the NAVAID family. Typically, any VOR or VORTAC will have a DME, although not necessarily. Your best bet is to reference an FAA sectional chart -- they will have the DME's marked.

John B - what the heck are you talking about? DME's inaccuracies are well-known, especially when close by or at long ranges from the station... GPS is far more accurate.

everybody got it wrong again. although not called a dme/dme approach, all flight management systems use dme/dme for positioning along with gps, vor/dme, vor/vor, inertial reference, (ins) etc. in fact there is no posioning data more accurate than dme/dme including gps or ins. so in all likelihood during an fms approach the fms is computing its "blended position" primarily with dme/dme.

As said above, DME is "distance measuring equipment"; with no azimuth or glideslope guidance, it wouldn't be a very usefull approach.