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Is flying through snow an icing hazard?

Updated: Jan 20

There are many opinions in the aviation community that flying through snow is not only an icing hazard, but also against Federal Aviation Administration (FAA) regulations for aircraft without a certified ice protection system. You can read one of them here from a recent post by the good folks at boldmethod. Keep in mind that each weather system is unique and there are many exceptions to the general discussion presented here and by boldmethod. Let's discuss some of the many factors associated with flying through snow.

Snow falling out of the base of a cloud means that there are fairly deep saturated conditions aloft. To produce snow typically requires that the cloud top temperature (CTT) be sufficiently cold. That usually means a CTT of -12°C or colder - colder is often better. In this situation, ice crystals can develop and lead to the development of snowflakes in the cloud aloft. If you are flying through snow below the cloud base, does that imply icing conditions exist? Just to be clear, this is not a discussion of flying in the clouds that are producing the snow, but below the cloud base. For the hazard of flying through clouds producing snow, read this post.

Snow is visible moisture. It can be mixed with other precipitation types that may include rain, freezing rain or ice pellets. In general, snow falling from the base of a cloud doesn't represent a significant airframe icing hazard unless it is mixed with other types of precipitation such as freezing rain. It can be an issue with induction icing, but not airframe icing. In the unlikely case that snow does adhere to the airframe, an exit plan should be executed.

Outside of a mixed precipitation scenario, snow is usually classified as wet or dry. Wet snow occurs when the static air temperature is at or above 0°C. That is, the snow falls into an atmosphere that is warm