Flying a drone directly over a person is not something Part 107 leaves to your judgment. Under § 107.105, a remote pilot in command may operate over human beings only in accordance with one of four defined categories — Category 1, 2, 3, or 4 — and outside those categories, sustained flight over people is simply not permitted. Chapter 1 named these categories in passing; this chapter is where the actual thresholds live, because which category you can use is decided entirely by the aircraft you fly and what its maker has shown about it.

The four categories form a ladder built around one idea: how much harm the aircraft could do if it fell on someone. At the bottom, Category 1 asks only that the aircraft be light enough and free of parts that would cut. Categories 2 and 3 sit in the middle — heavier aircraft allowed over people only once a manufacturer has shown, through a formal declaration of compliance, that an impact stays under a set injury threshold measured in kinetic energy. Category 4 is the top of the ladder: aircraft that carry a full airworthiness certificate, the path for machines too large to meet the injury numbers of the other categories. The rungs rise in what the aircraft must prove, not in what you as the pilot may intend.

The practical consequence is that the category is a property of the aircraft, established before you ever fly it over anyone — and the next four sections take each category in turn, then the chapter closes on the separate rules for moving vehicles. Your job as remote pilot is to know which category your aircraft actually qualifies for and to fly within it, because the permission to be over a person comes from the aircraft's proven safety, never from the operation looking routine.