One of the most significant expansions of the original Part 107 framework was the introduction of formal rules for flying small unmanned aircraft systems (sUAS) over human beings. Before these rules existed, flying a drone directly over people — other than those directly participating in the operation — was effectively prohibited without a waiver. The current regulations, codified in 14 CFR Part 107 Subpart D, establish four distinct categories that allow operations over people under specific conditions. Understanding each category, its requirements, and its limitations is essential both for passing the FAA Part 107 knowledge test and for conducting safe, legal commercial and recreational sUAS operations.
It is important to note that "operations over people" refers specifically to flight over human beings who are not directly participating in the operation and who are not located under a covered structure or inside a stationary vehicle that offers protection. The rules do not require you to avoid flying over your own crew or participants — those individuals may give informed consent. The rules target the protection of the uninvolved public.
The Four Categories Explained
Part 107 divides operations over people into Category 1, Category 2, Category 3, and Category 4. Each successive category generally permits either sustained flight over people or flight over moving vehicles, but imposes more stringent requirements on the aircraft or the operational environment.
Category 1
Category 1 is the most accessible entry point for flying over people. To qualify, the sUAS must weigh 0.55 pounds (250 grams) or less at takeoff, including everything on board. There are no FAA-issued airworthiness certification requirements and no required FAA Declaration of Compliance for Category 1. The aircraft simply cannot have any exposed rotating parts that would lacerate human skin upon contact. Because of the low kinetic energy involved at this weight, the FAA determined that the injury risk is sufficiently low to allow flight over people without additional aircraft-level requirements. Remote pilots operating under Category 1 do not need a specific aircraft marking or label — they need only ensure the weight limit is met and that the aircraft poses no laceration hazard.
Category 2
Category 2 allows operations over people with heavier aircraft, but requires the sUAS to meet a specific injury-risk threshold. The aircraft must be designed, produced, or modified so that it will not cause an injury to a human being equivalent to or greater than the energy transferred by a rigid object falling at 11 foot-pounds (ft-lbs) of kinetic energy. Additionally, the aircraft must not have any exposed rotating parts that could lacerate human skin. The manufacturer or a person modifying the aircraft must submit a Declaration of Compliance to the FAA, and the FAA must accept that declaration before the aircraft can be operated under Category 2. Accepted aircraft are listed in the FAA's publicly accessible database. Remote pilots are responsible for checking that their specific aircraft — including its serial number — has an accepted Declaration of Compliance before conducting Category 2 operations over people. The aircraft must also carry a legible label indicating its category eligibility.
Category 3
Category 3 applies a higher kinetic energy threshold than Category 2 — the aircraft must not cause injury equivalent to or greater than 25 foot-pounds (ft-lbs) of kinetic energy impact — but compensates by imposing stricter operational restrictions. Like Category 2, Category 3 aircraft must have an FAA-accepted Declaration of Compliance and must not have laceration-causing exposed rotating parts. However, the key operational restrictions are:
- The operation must be conducted over a restricted-access site where people on the ground are notified that a drone may be flying over them, OR
- The remote pilot must ensure the aircraft does not fly over any person who is not a direct participant in the operation for a sustained period — the aircraft may briefly pass over individuals, but must not hover or continuously fly above non-participants.
Category 3 is therefore a middle ground: heavier aircraft can fly over people, but either the site must be controlled (like a fenced event with posted warnings) or the pilot must actively manage flight paths to avoid sustained overflight of uninvolved individuals. In either case, Category 3 operations may never involve sustained flight over open-air assemblies of people.
Category 4
Category 4 is the most permissive category in terms of aircraft weight and sustained operations, but it demands the highest level of airworthiness documentation. A Category 4 sUAS must have an FAA-issued airworthiness certificate — the same type issued to manned aircraft — under 14 CFR Part 21. The aircraft must be operated in accordance with the conditions and limitations of that airworthiness certificate. This certificate is issued after the FAA evaluates the design and manufacturing processes of the aircraft. Category 4 also prohibits operations over people if the airworthiness certificate's operating limitations prohibit it. Remote pilots operating under Category 4 must comply with any applicable maintenance, inspection, and operational requirements tied to that certificate. This category is primarily relevant for manufacturers pursuing larger, more capable UAS platforms that have undergone rigorous FAA design approval.
Operations Over Moving Vehicles
Part 107 also addresses flight over moving vehicles. Only Category 1 and Category 2 aircraft may operate over moving vehicles in non-controlled or non-restricted areas. Under 14 CFR 107.145(b), Category 3 aircraft may operate over moving vehicles only within a closed- or restricted-access site, and only where all human beings located inside a moving vehicle within that site have been notified that a small unmanned aircraft may fly over them. Category 3 aircraft may not operate over moving vehicles outside a closed- or restricted-access site under any circumstances. Category 4 aircraft may operate over moving vehicles if the airworthiness certificate permits it. This distinction matters because flying over a highway or busy street — where vehicles and passengers are continuously present and cannot easily be warned — presents different risk profiles than a controlled airfield or private roadway.
Why These Categories Matter
The practical significance of the category system is substantial. Many commercial drone operations — real estate photography over public streets, infrastructure inspection near populated areas, news gathering at public events — place the aircraft over or near uninvolved people. Without compliance with one of these four categories, such operations either require a Part 107 waiver or must be restructured to avoid overflight entirely. Understanding which category your aircraft qualifies for determines what operations you can legally conduct, how you must document compliance, and what operational safeguards you must implement on site.
From a safety standpoint, the category system reflects the FAA's risk-based approach: kinetic energy at impact is the primary measure of harm potential. Lighter, slower aircraft with less stored energy receive lighter regulatory burdens; heavier platforms must demonstrate through testing and FAA review that their design mitigates injury risk before they can be flown over the public.
Key Numbers and Rules
- Category 1: 0.55 lbs (250 g) or less at takeoff; no Declaration of Compliance required; no exposed rotating laceration hazards.
- Category 2: Must not exceed 11 ft-lbs of kinetic energy at impact; FAA-accepted Declaration of Compliance required; label required on aircraft.
- Category 3: Must not exceed 25 ft-lbs of kinetic energy at impact; FAA-accepted Declaration of Compliance required; restricted-access site OR no sustained overflight of non-participants.
- Category 4: Must hold an FAA airworthiness certificate under 14 CFR Part 21; operations must comply with that certificate's limitations.
- Moving vehicles: Category 1 and 2 may operate over moving vehicles in unrestricted areas; Category 3 only within a closed- or restricted-access site with notified occupants; Category 4 per airworthiness certificate.
- None of the categories allow operations over people who are not participating when those people are under covered structures or inside stationary vehicles — those individuals are considered protected by their shelter.
Common Test Traps
- Confusing weight with kinetic energy: Category 1 uses a weight threshold (0.55 lbs). Categories 2 and 3 use kinetic energy thresholds (11 ft-lbs and 25 ft-lbs respectively). These are not the same thing, and the FAA test will probe whether you know which metric applies to which category.
- Assuming a Declaration of Compliance is self-certified without FAA acceptance: The FAA must accept the Declaration of Compliance before Category 2 or 3 operations over people are lawful. Simply completing the declaration form is not sufficient.
- Forgetting the sustained overflight rule for Category 3: A brief transit over a non-participant may be permissible under Category 3, but hovering or sustained flight over uninvolved people is not — unless the site is restricted-access with posted notifications.
- Overlooking the moving vehicle restriction: Category 3 cannot be used over moving vehicles in unrestricted areas, even if the aircraft otherwise meets all kinetic energy and declaration requirements. Under 107.145(b), Category 3 over moving vehicles is only permitted within a closed- or restricted-access site with notified occupants. Students sometimes assume that Category 3's higher energy threshold makes it more permissive overall — it is not, when it comes to moving vehicles.
- Mixing up Category 4 with the others: Category 4 is the only category that requires an FAA airworthiness certificate (like a manned aircraft). Do not confuse a Declaration of Compliance (Categories 2 and 3) with an airworthiness certificate (Category 4) — they are entirely different FAA processes.