Final answer:
The cowl anti-ice system should be turned on when OAT is low and conditions suggest the presence of ice. This is important for engine protection and overall aircraft safety. Aircraft operating manuals provide specific guidelines for anti-icing procedures.
Step-by-step explanation:
The cowl anti-ice system must be turned on while on the ground when the Outside Air Temperature (OAT) is at or below a certain threshold where icing conditions are expected or present
The specific temperature threshold can vary based on the aircraft's manufacturer guidelines, but it is commonly recommended to activate anti-ice systems when OAT is 10°C or below and visible moisture is present, or when the OAT is 10°C or below and operating on surfaces contaminated with snow, ice, slush, or standing water. While the cowl anti-ice system is particularly crucial for protecting the engine cowlings from ice accumulation, it also plays a role in ensuring the overall safety and performance of the aircraft during ground operations as well as during flight in cold weather conditions. It's important to refer to the aircraft's operating manual for the specific procedures and guidelines.