FAA Aircraft Dispatcher Complete Practice Exam

The condition that warrants the need for engine anti-icing measures during taxi is when the temperature is below 10°C with moisture present. At these temperatures, moisture in the form of rain or humidity can lead to the accumulation of ice on engine components. The formation of ice can potentially disrupt airflow and affect engine performance. Engine anti-icing systems are designed to prevent ice buildup, ensuring the engines operate efficiently and safely.

While heavy precipitation and low visibility can also necessitate careful procedural considerations, they do not specifically indicate that engine anti-icing is required. The presence of ice on the wings is a different issue that pertains more directly to aerodynamic performance rather than engine performance during taxi. Thus, it is the combination of lower temperatures and moisture that most directly relates to the need for engine anti-icing measures.