How is night defined in aviation terms?

In aviation, night is defined as the period that begins at the end of evening civil twilight and concludes at the start of morning civil twilight. This definition is critical as it establishes specific operational guidelines for pilots and their responsibilities when flying during these hours.

Civil twilight is the time when the Sun is between 0° and 6° below the horizon, providing enough natural light for most outdoor activities without additional lighting. By defining night in this manner, aviation regulations ensure that pilots acknowledge the reduced visibility and altered flying conditions that come with flying during these darker hours.

Understanding this definition helps pilots to know when additional lighting requirements for their aircraft, such as navigation lights and position lights, must be utilized, enhancing overall safety in nighttime operations.