Ok, I couldn

Thanks for taking the trouble to post all that information, Tord, and sorry for late reply.DME, hmmm....,could it be the transponder you're referring to? :-)Best wishes,Frank

Frank,DME= Distance Measuring Equipment.Mot every VOR has a DME also there are stand alone DME's without VOR.Frans Dekker / TFF074

Frans, I won

Okay, Tord, maybe I was misled by your 'clue' :-), but I think I understand it now("in common with").There is a transceiver on board the plane which sends an electronic pulse to the DME ground station and is able to calculate distance to the station by measuring the time it takes for the pulse to return. Note that the distance measured is the slope distance, not the distance across the ground(not sure if this is corrected for, or not?).DME equipment uses a similar method to the transponder, except it measures distance rather than altitude and speed(Mode C).BR,Frank

:-beerchug Exactly. My reference (lame as it may be) to ATC was that DME is an example of a secondary radar i.e. a request-response system. In the case of ATC it is indeed the transponder system that works in this manner. I

Readhttp://www.flightsimaviation.com/aviation_...ipment_DME.html and be an expert;-) Frans Dekker / TFF074

Hi Tord,Well, looks like I got something right today! :-).Thanks for the challenge.BR,Frank