When are wing anti-ice and engine anti-ice typically activated on a narrowbody?

• A. In icing conditions per procedures; wing anti-ice is used when wings are at risk of ice, engine anti-ice is used when engine surfaces require protection.
• B. Wing anti-ice is always on; engine anti-ice is never used.
• C. Wing anti-ice is used only on the ground; engine anti-ice only in flight.
• D. Both are activated automatically at temperature thresholds regardless of icing conditions.

Answer: (A)

Wing and engine anti-ice are activated when icing conditions are present and per the aircraft’s published procedures. Wing anti-ice protects the leading edges of the wings because ice there changes the airfoil shape, increasing stall speed and reducing lift. Engine anti-ice protects the engine inlet and nacelles because ice can restrict airflow, cause compressor surges, or even flameout. The activation is guided by documented icing procedures and may be automatic (via ice detectors) or manual, but it isn’t simply a temperature threshold turned on regardless of conditions. In practice, both systems are used during icing conditions and left off when there is no icing risk.