In what environmental conditions should icing be avoided?

Icing should be avoided in conditions below 0°C with visible moisture because these are the prime conditions conducive to the formation of ice on the helicopter's surfaces. When temperatures are at or below freezing, and there is moisture present in the air—such as in clouds, rain, or even mist—there is a significant risk of ice accumulation on the rotor blades, fuselage, and other critical components. Ice can alter the aerodynamic performance of the aircraft, leading to increased weight, reduced lift, and potential control issues, which is especially hazardous for helicopters that rely heavily on rotor efficiency for flight maneuvers.

While visibility of moisture in warmer conditions (above 0°C) does not typically lead to icing, because the temperature is above freezing, it is essential to remain vigilant in colder conditions where ice can form even with light precipitation. Thus, the correct choice reflects the specific combination of low temperatures and moisture that poses the greatest risk for icing scenarios in flight.