What is one visual cue indicating supercooled large water droplet (SLD) conditions?

The visual cue indicating supercooled large water droplet (SLD) conditions is the formation of ice on the propeller spinner, which can extend back to the propeller blades. This phenomenon occurs because SLDs are larger than typical cloud droplets and can exist in a supercooled state, meaning they remain liquid even below freezing temperatures. When aircraft encounter these supercooled droplets, they tend to freeze upon contact with surfaces that are at or below freezing, leading to noticeable icing.

The reason this cue is particularly indicative of SLD conditions is that the formation of ice on the spinner and propagating to the blades indicates that large quantities of supercooled liquid water are present in the atmosphere, capable of creating significant icing problems. This is a clear warning to pilots that they may be flying in conditions that could adversely affect aircraft performance and safety due to the potential for severe ice accumulation.

In contrast, other options may represent icing conditions but do not specifically relate to the presence of supercooled large water droplets. For example, while ice forming on the leading edge of the wing or antennas can signal ice accumulation, they are not as directly related to the presence of SLDs as the specific scenario involving the propeller spinner and blades. Clear