Mike Rapoport wrote:

There is no doubt that forecast icing is known icing to the FAA and the
NTSB. This has been beat to death many times here and in every aviation
publication.

The problem is (as always) the edge cases:

1. If icing is forecast at 15,000 ft, is flight at 3,000 ft considered a
flight into known icing? What about a flight at 14,000 ft?

2. The U.S. Current Icing Potential is a percentage, not a boolean. Is a
current icing potential of 10% equivalent to known icing? What about 25%?

3. Is VFR flight under a blue sky considered a flight into known icing when
a high probability of icing was forecast at that altitude in that area?
What about VFR under a high overcast with good visibility and no visible
precipitation?

etc.


All the best,


David