Category 1 is the simplest path over people, and § 107.110 defines it with two facts about the aircraft. First, it must weigh 0.55 pounds or less — and not just at takeoff. The limit holds throughout the duration of each operation and counts everything on board or otherwise attached to the aircraft, so a camera, a battery upgrade, or a payload that pushes the total past 0.55 pounds drops you out of Category 1 mid-flight. Second, the aircraft must not contain any exposed rotating parts that would lacerate human skin upon impact — in practice, propellers shrouded or guarded so a strike would not open a cut.

What makes Category 1 the easy path is what it does not require. Unlike Categories 2 and 3, it asks for no manufacturer’s declaration of compliance and no injury-threshold testing — an aircraft either meets the weight and the exposed-parts conditions or it does not, and the remote pilot can confirm both by knowing the aircraft. That is the trade the rule makes: keep the machine light enough and free of cutting parts, and the FAA treats the risk to a person underneath as low enough to permit the overflight without paperwork.

There is one important addition even Category 1 does not escape. Under § 107.110(b), no remote pilot may operate in sustained flight over an open-air assembly of human beings unless the operation also meets the Remote ID requirements of § 89.110 or § 89.115(a). So a light, guarded Category 1 aircraft clears the routine over-people bar, but the moment the people below become an open-air assembly, Remote ID becomes a condition of the flight. What Remote ID is and how those two paths work is the subject of Chapter 6; here the point is simply that crowds raise the bar, even for the lightest category.

Everything in that sentence turns on a phrase Part 107 never defines, and the FAA’s own guidance is where the working meaning lives. AC 107-2A explains that because the term is not defined by regulation, the agency applies it case by case — weighing the density of people who are not participating in the operation against the size of the operational area — and it gives examples on both sides: sporting events, concerts, parades, political rallies and community festivals are the kind of gathering likely to count, while individuals or small groups taking leisure in a park, or someone riding along a bike path, generally are not. Read that as guidance on how the FAA interprets the phrase, not as text sitting in the rule. And because no numerical line exists in either place, the working posture is the conservative one: treat any dense outdoor gathering as potentially an open-air assembly and plan the flight as though it is. That caution is load-bearing rather than merely prudent, because the same undefined phrase decides whether this lightest category needs Remote ID at all and — as the next section shows — whether a Category 3 aircraft may be at the site in any form.