Which icing type is generally less than perceptible?

Trace icing is characterized as being generally less than perceptible, which means that it may not be easily noticed by pilots during flight. This type of icing occurs when there is a very minimal accumulation of ice on the aircraft. It can still pose safety concerns, especially when considering conditions that could contribute to further accumulation, but pilots often do not detect it during their usual pre-flight checks.

In contrast, moderate icing, severe icing, and light icing each involve more noticeable levels of ice accumulation. Moderate icing can lead to a clear reduction in aircraft performance and requires action from pilots. Severe icing poses significant risks and requires immediate attention, while light icing, while still a concern, is typically more noticeable than trace icing but less impactful than moderate icing. Understanding these categories helps pilots assess the potential impacts of icing conditions on flight safety.