If Type II or IV wing fluids have been applied, when should wing anti-ice be activated?

• A. Only after thrust increase for takeoff
• B. Only prior to thrust increase for takeoff
• C. Only during taxi
• D. Only during landing

Answer: (B)

When Type II or IV fluids are present, protection relies on having the wing anti-ice system operating before you start the takeoff roll. These fluids give temporary protection, but they don’t substitute for heating the leading edges. Turning on wing anti-ice before you advance the thrust ensures the heated leading edges are active during the takeoff run and the initial climb, while the holdover protection is still valid. If you wait to apply anti-ice until after pulling thrust, you risk unprotected surfaces during the critical takeoff phase, when ice formation would be most dangerous. Activating anti-ice during taxi or after takeoff would not provide the needed protection right as you begin the takeoff acceleration.