If sunset is at 2021, when must a recreational pilot terminate the flight?

The requirement for recreational pilots concerning flight termination at sunset is clearly defined in aviation regulations. Pilots operating under visual flight rules (VFR) must conclude their flights by sunset unless they are authorized to fly in reduced visibility conditions or under instrument flight rules (IFR). Sunset is the point at which the sun completely descends below the horizon, marking the end of diurnal daylight.

Choosing to terminate the flight at sunset ensures that the pilot adheres to safety regulations while accounting for visibility. Continuing to fly beyond this point could introduce risks associated with reduced light conditions, heightening the difficulty of navigation and obstacle avoidance.

The other options refer to time periods after sunset or during twilight when visibility may further decline. However, the clear standard for recreational pilots is to land before sunset to ensure safety and compliance with flight regulations.