What is the required condition for cowl anti-ice to be activated on the ground?

The correct condition for activating cowl anti-ice systems on the ground is that the Outside Air Temperature (OAT) must be 10°C or below in visible moisture. This condition is crucial because visible moisture, such as rain, sleet, or snow, increases the risk of ice formation on critical engine and aerodynamic components.

At temperatures above 10°C, the likelihood of ice accumulation in the presence of moisture is significantly reduced, making it unnecessary to activate the anti-ice systems. Therefore, cowl anti-ice is specifically designed to protect against ice ingestions during conditions when temperatures are low and moisture is present, which can lead to hazardous icing that affects engine performance and safety.