Originally Posted by IO540
I don't believe that "most" icing encounters are fatal
I don't believe that anybody has claimed that. If you are making a response to my option (a), then you need to read it again.
Originally Posted by IO540
But, I still don't get how one is supposed to conduct oneself, given the absence of meaningful "official" icing data.
The question has now moved on and I don't understand what you are asking. Originally, the question was one of how to distinguish between Forecast and Known icing. You have learnt that Known icing is not a term used by the CAA thusfar (although it looks to be putting in a re-appearance under EASA). As a result, you are simply prohibited from flying a non-icing-approved aircraft into Icing Conditions. How you "are meant to conduct yourself" is obvious is it not? You use your skill and experience along with all available weather data to determine that your planned flight is safe and lawful. Should you subsequently encounter icing to a degree by which you are noticed by regulators, you should prepare to justify the decisions you took.
The fact that all 215s contain an ice warning is not going to be of particular help to the case of a regulator in nailing you down. The fact that you actually encountered ice despite your planning, will not help your case.
I think that you may be trying to extract more mileage from this than is available to extracted. If your real point is that you don't like the blanket warnings on 215s, then join the club. The Met office has dumbed-down and generalised many aspects of its forecasts in recent years.
2D