How are cowl flaps typically set during the cruise portion of the flight?

During the cruise portion of flight, cowl flaps are typically set to closed unless the aircraft is experiencing very high temperatures. This configuration is designed to optimize engine performance and efficiency.

When the cowl flaps are closed, they minimize drag, which is beneficial for fuel efficiency and speed during cruise flight. Additionally, the engine has sufficient airflow for cooling at cruising speeds and altitudes, reducing the need for open cowl flaps unless the engine temperature rises above the normal operating range.

Only in very hot conditions, where engine temperatures might exceed safe limits, would the pilot consider opening the cowl flaps to increase airflow and enhance cooling. Thus, setting the cowl flaps to closed during cruise is a common practice under standard operational conditions, supporting engine performance while maintaining aerodynamic efficiency.