What should pilots be most concerned about during conditions of moderate icing?

In moderate icing conditions, the primary concern for pilots revolves around the potential effects on the aircraft's performance and handling. Moderate icing can lead to significant increases in weight due to accumulated ice, which can ultimately affect lift and drag characteristics. This situation can compromise the ability of the aircraft to maintain altitude and require pilots to consider diverting to alternate airports where conditions may be less severe or more manageable.

While issues such as extended flight duration, systems malfunction, and difficulty in maintaining altitude are also valid concerns, diverting flights becomes crucial since it addresses the immediate operational safety of the flight. The accumulation of ice can impair the aircraft's performance enough that it necessitates changing the flight plan to ensure safety. Thus, the risk of icing significantly influences pilots' navigation and operational decisions, making the need for flight diversion a top priority.