According to 14 CFR Part 107, what is necessary to operate a small unmanned aircraft after official sunset?

To operate a small unmanned aircraft after official sunset under 14 CFR Part 107, the use of anti-collision lights is required. This regulation is in place to enhance the visibility of the drone during nighttime operations, ensuring that the aircraft can be seen by other aircraft and avoiding potential collisions.

Anti-collision lights must be used to provide a bidirectional light signal that can be visible from a significant distance. The requirement for these lights helps maintain safety standards during operations in low-light conditions, allowing both the pilot and others in the vicinity to be aware of the aircraft's presence.

The other options do not fulfill the regulations concerning nighttime operations. A flight plan is not mandated for each flight under Part 107, night vision goggles are not a requirement for pilots, and having two pilots in command is not necessary for standard operations. Thus, the requirement for anti-collision lights stands out as the essential condition for flying after sunset.