Icing Risk Management
Asked by: Bruce Mamont 2373 views Flight Instructor, Instrument Rating, Weather
I have been struggling to refine my decision criteria for flight into potential icing conditions during instructional flights and would appreciate advice from CFI-Is.
Formerly, my rule was: no flight in clouds above the freezing level. My reasoning was that clouds contained liquid water (at the altitudes in which I fly with students, generally below 7,000 MSL), liquid water would freeze to the airplane's structure, and any ice on a 172 was unacceptable unless I could quickly descend below the freezing level remaining at/above the MEA or to VMC with sufficient terrain clearance.
I'd been cancelling most of my flights when these conditions were reported or forecast; I was counseled that this was too conservative.
I'm not asking the "what's legal?" question regarding the definition of "known icing conditions". I wouldn't fly into an area where PIREPs reported icing, but PIREPs result from people flying. People staying on the ground because of potential icing don't report.
What are good personal minimums? No flights into areas of predicted liquid precip above the icing level (that's my refined no-go rule at present)? No flight into an area where the RUC depicted near saturated (what percentage?) air above the freezing level? No flight when the CIP reported more than a particular (5%? 25%?) icing probability? No flight into an AIRMET ZULU defined area?
Thanks.
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