Post-Cold Frontal Stratocumulus Clouds Create Recipe for Airframe Icing

Pilots should never allow themselves to be fooled by the snow.

Scott Dennstaedt, Ph.D

Friday, February 21, 2025 at 08:52 AM ET

Verified

Edited By: tccjeremy

Airplane flying high above stratocumulus clouds during the morning sunrise. [Adobe Stock]

Key Takeaways:

Contrary to popular belief, snow-producing clouds can pose a significant airframe icing risk due to the presence of supercooled liquid water, even for aircraft equipped with icing protection systems.
Post-cold frontal stratocumulus clouds, even when shallow and producing snow, are particularly hazardous as they often contain high concentrations of supercooled liquid water near their tops.
Pilots should exercise caution when flying into snow-producing cloud decks, especially with showery snow, mixed precipitation, or when cloud top temperatures are relatively warm (e.g., warmer than -15°C), as these conditions increase the likelihood of moderate to severe airframe icing.

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Are snow-producing clouds an airframe icing risk? The short answer is yes, which will likely surprise most readers who fly under instrument flight rules. While your mileage may vary, depending on the conditions, heavy ice within snow-producing clouds can even overwhelm an aircraft with a certified icing protection system.

In fact, a study done by Steven Green of Flight Operations Research suggests that if you look at icing accidents and incidents that occurred during which precipitation was reaching the surface, freezing precipitation (freezing rain or freezing drizzle) is present in 33 percent of the total events and snow is present in 32 percent of the events; these conditions are not mutually exclusive, as 7 percent of the events include both.