I think what OP is saying is that all this stuff doesn't really matter,
because an ALJ bought the FAA's argument that forecast icing, plus a smidgen
of knowlege (which could be a PIREP, could be freezing temps) is known
icing.

It's easy to understand that the FAA's use of language is just like Alice in
Wonderland, "When I use a word, it means exactly what I want it to mean,
nothing more, and nothing less." They provide the language, in the AIM or
the FARs, and then get to tell the ALJ exactly what it means. The ALJ and
the NTSB are bound to accept that interpretation, no matter how much they
may disagree.



Actually, I didn't use the word 'implicit'. But yes, I did point out that
the AIM now explicitly distinguishes forecast icing conditions from known
icing conditions. I'm baffled as to how you could disagree (given the
definitions I quoted), but if you do, I'd be grateful if you'd explain
why.