ILS/DME Approach
Greetings my fellow aviators. I have been pondering this for a while and have not satisfied myself with a proper answer (reinforced by a paper reference). What is the main difference between the ILS and the ILS/DME approach when you consider that a typical Cat 1 approach, the localizer is intercepted at a specified altitude until GS intercept, then down to a DH where a decision is made to land/Go Around. At no point is a distance required on the approach.
My only thought is that the DME portion would only be pertinent in a missed approach when a DME would be required in the Missed approach phase. My other thought of the pertinence of the DME on the localizer would be for a LOC only portion in case of a failure of the GS while on the approach which reverts to a LOC approach. If the LOC requires distance based on the DME of the LOC rather than a VOR , then I would again see the significance.
The simple question is this, why not just call it an ILS approach rather than the ILS/DME approach?. Also if the DME of the LOC is notamed inoperative, can you fly the ILS/DME approach (localizer and GS operative), and what is your DH? Is it a LOC MDA or the published ILS DH?