ferris, nice to have you back in a sensible discussion ...
You make a good point that options are different once the descent for each aircraft has started. My reply was on the basis that both were already established in the descent, as I understood that to be the position in the original thread question. I fully accept that a better solution would have been to anticipate the potential descent conflict by agreeing the descent speeds with the aircraft, well before either have reached TOD. Don't forget, incidentally, that the TOD position will itself vary, depending on the descent speed chosen.
Your suggestion that
If you leave the first a/c going slow, you HAVE TO SLOW THE NEXT (and all subsequent) a/c, which puts the next a/c in an inefficient state.
is a valid point. However the end result of the alternative is that all aircraft in the sequence are then forced to maintain the higher speed descent, which may well not be their individual preference - indeed some may even decline if they are tight on fuel. Furthermore, if you are holding at the fix anyway, perhaps the "horizontal holding" effect of the slower speed would be preferable for that reason and help the TC controller.
I understand you reasoning but I still feel that, if you have to impose a speed against the aircraft's original preference, it should be the slower speed rather than the faster one.
JD
