Operating aircraft during the hours of darkness involves specific regulatory and operational considerations. A primary delineation centers on the period between the end of evening civil twilight and the beginning of morning civil twilight. This timeframe, often used in official reports and flight planning, defines the most restrictive period for flight, impacting visibility and requiring specialized training and equipment. For instance, pilots require instrument ratings to navigate solely by instruments during this period, and aircraft must possess specific lighting configurations.
A second understanding revolves around the time from one hour after sunset to one hour before sunrise. This definition is often employed in logging flight time for pilot certification and currency requirements. Pilots accumulating hours within this window receive credit for nocturnal flight experience, building proficiency in low-light conditions and utilizing night-vision aids. The ability to demonstrate competence within this environment enhances pilot safety and skill.