If not equipped with required position lights, when must an aircraft terminate flight?

The requirement for position lights on an aircraft is crucial for ensuring visibility and safety during flight, especially in limited visibility conditions. According to aviation regulations, aircraft must be equipped with operational position lights when flying during the hours of darkness or when visibility is hampered.

The correct answer highlights that an aircraft must terminate its flight at sunset if it does not have the required position lights. This is because once the sun sets, the natural light diminishes, and the lack of position lights would pose a significant risk of collision with other aircraft, as well as not being visible to ground personnel or structures.

In contrast, the other options suggest extending the flight duration beyond sunset, but without position lights, doing so increases the risk of accident and violates safety protocols established by aviation authorities. Therefore, the regulations clearly dictate that without the necessary lights, the safe and responsible action is to terminate the flight at sunset.