What is the most effective way to prevent throttle ice?

• A. Open and close the throttle.
• B. Use Carburetor air heat continuously at temps below 0.
• C. Use carburetor air intake heating systems.
• D. Do nothing.

Answer: (C)

Ice forms in a carbureted engine when moist air entering the carburetor cools and freezes on the throttle plate and in the venturi. The most effective prevention is to introduce heated air into the carburetor—the carburetor air heating system—so the air-fuel mixture stays warm enough to prevent ice from forming. This heating raises the air temperature at the point of contact, directly addressing the icing cause.

Opening and closing the throttle doesn’t prevent ice; it changes airflow but not the temperature that causes icing. Using carburetor heat continuously at temperatures below freezing isn’t the practical or standard approach in most procedures, and doing nothing guarantees icing.