When should anti-ice systems be activated and what indicators support this decision?

• A. In icing conditions or forecasted icing; indicators include weather information and icing warnings; The crew may turn on wing and windshield anti-ice as required
• B. Anti-ice is always on
• C. Anti-ice should be off in icing
• D. Anti-ice only used on the ground

Answer: (A)

Activating anti-ice when icing conditions exist or are forecast is essential to prevent ice from forming on critical surfaces and degrading aircraft performance. Ice on the wing leading edges alters airflow, increases weight, reduces lift, and can obscure sensors or the windshield, so taking preventive action is the safest choice.

The decision is guided by available information: weather reports and forecasts, METARs/TAFs, PIREPs, and icing advisories or warnings. If these indicate icing or a high likelihood of icing, the crew should turn on the wing anti-ice and the windshield anti-ice as required. This may be done proactively when entering known icing areas or as soon as icing is encountered, rather than keeping anti-ice off or using it only on the ground.