100%
Useful post. I am disappointed to hear that your SOPs "clearly state" that you should, in effect, break an ATC instruction. (Did I understand you correctly?) If 160 to 4 doesn't work then, for pitty's sake, lets get together and agree what does work and apply it. The current position is akin to anarchy. In theory, 160 to 5 might mean reduced use of 2.5nm spacing (because speed differentials on short final would last for longer giving greater risk of catchup) but if that is the price to be paid so be it.
I don't think starting to slow .5 or 1nm early is really the problem. It is those who are at 145kts at 5nm with traffic behind doing 160 to 4 - especially if vortex is involved - that put the ATCOs in an illegal position very quickly. This issue must be addressed.
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