FAA Might Redefine Known Icing

In an unusual policy step, the FAA sought comments last month on a draft letter of interpretation regarding the meaning of the term “known icing conditions,” used–but undefined–in the FARs. A June 2006 FAA regional counsel letter defined known icing as existing “when visible moisture or high relative humidity combines with temperatures near or below freezing.” The FAA agency-wide draft interpretation said, “If the composite information indicates to a reasonable and prudent pilot that he or she will encounter visible moisture at freezing or near freezing temperatures and that ice will adhere to the aircraft…then known icing conditions likely exist.” Robert Miller, the CFI-I who asked the FAA for the interpretation, said he is happy with the agency’s work, as it removes the automatic illegality of entering a sub-freezing cloud.