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Aircraft Icing Recognition - The Good, The Bad, The Ugly

by John M. White |

One of the problems with airframe icing and the FAA definitions is - how do you know the difference between intensities in flight?  The definitions are unclear, and lead to confusion on the part of pilots. 

For example, if an unprotected aircraft gets into icing does the pilot continue to fly until a problem or hazard occurs?  How can pilots tell the difference between trace and light icing if neither presents a problem or hazard for at least an hour?  How would a pilot know if the intensity changes?Click on image to enlarge

If deicing boots are used and ice removed, how do pilots determine what the next icing condition, if any, is?  How can icing ever be severe for aircraft certified for flight into known icing conditions when such certification means the ice protection equipment will not be overwhelmed?

When it comes to 14 CFR Certification and Operating Rules there is a problem between the presumption of flightworthiness of aircraft that are certificated for flight into icing conditions?  14 CFR 135.227(d) permits aircraft to fly into severe icing conditions if the aircraft is certificated for flight in known icing conditions.  However, according to the definition of severe icing considers such icing to be impenetrable, even for protected aircraft.

Present icing intensity definitions contain nothing that can be calculated or measured.  Therefore they are practically useless.

In the final analysis anyone flying in known icing conditions is on their own.  The pilot in command is ultimately responsible for the safety of the aircraft, passengers and crew, so if a problem arises and there is injury or death to passengers and/or crew, the pilot will surely be blamed, at least in part.

So if you fly in icing conditions be aware that you do so at your own peril.  As an FAA Air Safety Inspector told me recently, "We're not happy until you'e not happy!"  Keep that in mind!

Until next time keep your wings straight and level Hersch!


When it comes to testing new aircraft or determining maximum performance, pilots like to talk about "pushing the envelope." They're talking about a two dimensional model: the bottom is zero altitude, the ground; the left is zero speed; the top is max altitude; and the right, maximum velocity, of course. So, the pilots are pushing that upper-right-hand corner of the envelope. What everybody tries not to dwell on is that that's where the postage gets canceled, too.

— Admiral Rick Hunter, U.S. Navy.

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