What should you do to clear the engine during a prolonged glide?

To clear the engine during a prolonged glide, increasing the power to about 1500 RPM is recommended. This action helps to maintain engine responsiveness and can assist in preventing fouling of the spark plugs. When an aircraft is in a prolonged glide with reduced power settings, especially if the engine is at idle for an extended period, there is a risk that carbon deposits can accumulate on the spark plugs, leading to potential engine issues. By applying power to approximately 1500 RPM, the engine remains operational and efficient, allowing for a clearing of fuel/air mixture and keeping the engine in a healthy operational state, ready for power application when necessary.

In contrast, reducing the throttle completely would lead to a complete loss of engine power, which is undesired in this scenario. Pulling the mixture to idle could also negatively impact the engine's performance, as it would lean the mixture excessively, further risking engine fouling. Performing an emergency landing might be considered if the situation worsens, but the primary goal during a glide is to maintain engine functionality, which is best achieved by adjusting the power appropriately.