"Bob Gardner" wrote in message
. ..
As George said, in Adminstrator vs Bowen, in 1974, the Administrative Law
Judge said, more or less, "known does not mean a near-certainty of icing
conditions, only that icing conditions are being reported or forecast."

But that 1974 decision is at odds with the current AIM, which defines
various icing conditions in section 7-1-23
(http://www.faa.gov/atpubs/aim/Chap7/aim0701.html#7-1-23):

"Forecast Icing Conditions--Environmental conditions expected by a National
Weather Service or an FAA-approved weather provider to be conducive to the
formation of in-flight icing on aircraft."

"Known Icing Conditions--Atmospheric conditions in which the formation of
ice is observed or detected in flight."

So according to the AIM, forecast icing is not tantamount to known icing.
Rather, only a PIREP of icing (or a pilot's own observation in flight)
constitutes known icing.

Although the AIM isn't regulatory, it does purport to furnish information
that is relevant to a pilot's understanding of FAA regulations. So when the
latest AIM defines a term that the FARs use but don't define, it would
violate due process to expect pilots to know and use some other definition
instead. (Does anyone know if the current AIM definitions were present back
when the previous rulings on known vs. forecast icing conditions were
issued?)

--Gary