What is the safe vertical clearance to allow WT to dissipate in a no wind situation from slow and heavy CAT?
I don’t know how far away in time and distance you need to be to be “safe” (it depends on your aircraft) but I have experienced serious wake 1,000’ below and 5 minutes after a heavy jet. I suspect in ideal circumstances it could go much lower/longer.
I think atmospheric conditions play a large part: vortices appear to last much longer and keep intensity in a stable layer or where there is no preexisting turbulence.