Most of what the average pilot thinks they understand about “known icing” is probably mistaken. This also is often intentionally implanted by well-meaning educators who may also be confused (sorry – we can fix this…) I know this from giving flight tests – where applicants are required to understand this information – but also from discussing winter flights in the clouds with other pilots. I often see fear, misunderstanding and endure incriminating accusations of craziness any time I admit to flying in a “cold cloud” between September and June.

Certainly, one sure way to create safety in aviation is to stay on the ground.  So, unfortunately, we have created a “boogeyman” to protect the innocents that also keeps every other pilot without a FIKI airplane from flying IFR (or even VFR) all winter long. This “cold cloud club” also points an accusing finger at any pilot who goes flying in the winter clouds calling them crazy and unsafe. This is an unfortunate situation that creates more heat than light.

Obviously, caution is a good thing, and I would be the first to admit there are definite, definable risks in this environment (as there are everywhere). But ignorance, denial, fear, and finger-pointing are also not good strategies for successful aviation. As in any risk-management situation, we need definite skills, knowledge and training to fly safely in the winter. Winter can provide some of the best flying – there are also clouds that are safe and strategies to mitigate the risk. Please stay with me here and let’s poke the bear a little.

There is no regulation prohibiting flight into “known icing” for part 91 operations. (Throw that into a hangar flying session as a good “fire starter”)

The legal prohibition is actually in the “operating limitations”  of your POH or AFM – and you might have to do a little digging to find it. In addition to “approved” and “prohibited” operations for Flight Into Known Icing (FIKI), there are several levels of “semi-FIKI” aircraft, so the plot thickens. The FAA legal “gotcha” is actually CFR 91.13 prohibiting “careless and reckless operation”  – which is included in every pilot violation or sanction. As always, you are PIC and you choose your conditions and tools to conduct aviation as you see fit; just do it legally and safely.

The definition of “known icing” is also notoriously slippery, having changed numerous times over the years. To find a solid legal definition you need to consult several good sources:  Chief Counsel Letter of Interpretation,  the Federal Register,  the Advisory Circular and the AIM. Reading and understanding all of these in detail is the first step in flying safely in potentially icing weather; know the rules and cautions. (Also a good idea for flight tests)

“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 along the proposed route and altitude of flight, then known icing conditions likely exist.

Most recently – and what I hear often on most flight tests is – “known icing” is indicated (and flight prohibited) by “a current PIREP reporting icing.” For years this was regarded as the sure arbiter of “known icing,” and it certainly might be a time not to fly, but the FAA in the AIM seems to even be backing off this as a definition or legal justification for sanction:

“Because of the variability in space and time of atmospheric conditions, the existence of a report of observed icing does not assure the presence or intensity of icing conditions at a later time, nor can a report of no icing assure the absence of icing conditions at a later time.”

The definition of “known icing” migrated from overly permissive to excessively restrictive in the late 1990s, limiting flight in any visible moisture below freezing. This draconian interpretation got the “cold cloud avoidance” started. As such, “known icing” became the boogeyman everywhere and always in winter clouds and the only legal IFR solution was “park it till June.” (Sorry for friends south of the equator).

The current interpretation, issued in 2009, allows for pilot discretion in evaluating and choosing a “reasonable and prudent” course of action in most conditions: CFR 91.3 rules: (PIC). If you examine most “textbook” icing accidents, you see some really terrible conditions pilots failed to avoid and usually bad decisions made with partial information or “emotional planning tools.” The FAA in giving pilots discretion is also providing enough rope to hang themselves. Like all aviation decisions, be comprehensive in your planning and cautious in your decisions.

So how does a safe pilot mitigate risk and fly IFR safely in the winter? Parking the plane until June in the North is super safe, but totally ruins any utility and efficiency in aviation (cold cloud club). Launching without care or preparation to “get ‘r done” is a really bad expedient. Between these two polar forces of caution vs. efficiency is where we negotiate safety in aviation. Flying on the east side of the Great Lakes for 40 years, I have seen pilots on both sides of this caution equation. I think the best answer is to prepare more carefully, fly with more caution (acknowledging known hazards) and allow a greater margin of safety for escape in the event of surprises.

So first, safety in potentially icing conditions requires a more comprehensive and careful preflight analysis, and there are amazing new tools especially from the NWS Forecast Icing Potential,FIP and Current Icing PotentialCIP CFR 91.103 (all available information). Knowing weather theory is also essential since this process is in motion. (Scott Dennsteadt’s excellent weather book is a great start) Second, obtain (and issue) PIREPS for any and all changes (especially tops and temps.)  This is the best real-time peer-to-peer information sharing system we currently have. During dynamic winter conditions where a few degrees of temperature make all the difference, information sharing is essential. Lastly, always assure a safe escape route if you suddenly encounter icing, since it is impossible to forecast precisely and the consequences of unforecast icing are both terrifying and dangerous. Clear air below (but above the MEA) is best, but lateral diversions and big picture awareness are essential.

The FAA’s newest icing AC 91-74B is well written with lots of good information. The NASA Glenn Research Website has a very good online training for pilots I highly recommend – knowledge, information and caution. Finding a savvy CFI with lots of experience in winter weather is your best educational resource (as always) since you need a mentor to explore any potentially-hazardous phenomenon safely. Stay warm and fly often!

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About the author 

David St. George (Lifetime Member)

David St. George learned to fly at Flanders Valley Airport in 1970. Proving that everyone is eventually trainable, he became an FAA Gold Seal Flight Instructor for airplanes (single and multi, instrument, and glider) and serves the Rochester FSDO as an FAA Designated Pilot Examiner. In this capacity, he gives flight tests at any level from sport pilot to ATP and CFI. For 25 years David was East Hill Flying Club's 141 Chief Instructor and manager. David holds multi and single engine ATP pilot certificates, with pilot ratings for glider and seaplane and several jet type ratings. He recently earned his 13th renewal as a Master Instructor and owns an Aeronca Champ so he can build hours for that airline job!

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