2.1 Subcategory A1: Flying Over People, C0/C1 Rules & Crowd Overflight Ban

2.1 Subcategory A1: Flying Over People, C0/C1 Rules & Crowd Overflight Ban

[!NOTE] Regulatory Baseline: Subcategory A1 is codified under Point UAS.OPEN.020 of Commission Implementing Regulation (EU) 2019/947. It is colloquially termed the "fly over people" subcategory, but this operational privilege is strictly bounded by aircraft class markings, kinetic energy thresholds, and a universal, absolute ban on overflying assemblies of people.

In the European Union unmanned aircraft regulatory architecture, Subcategory A1 permits operations in populated, urban, and suburban environments where uninvolved persons are present. Because human beings on the ground are exposed to potential mechanical failure or pilot error, European aviation safety regulators mitigate ground risk by strictly capping the mass, speed, and kinetic energy of the aircraft permitted to operate in this operational envelope.

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The Operational Architecture of Subcategory A1

Unlike traditional model aircraft rules that demanded vast rural separation distances, Subcategory A1 allows remote pilots to conduct missions close to human activity—such as residential real estate photography, localized infrastructure inspection, or news gathering. However, the degree of proximity to uninvolved bystanders depends directly on the aircraft's CE class marking and physical design.

Under UAS.OPEN.020, Subcategory A1 accommodates two primary hardware tiers:

1. Class C0 unmanned aircraft (MTOM < 250 g) and privately built drones with an MTOM below 250 g.
2. Class C1 unmanned aircraft (MTOM < 900 g or impact energy < 80 Joules).

+-----------------------------------------------------------------------------------+
|                         Subcategory A1 Operational Scope                          |
+-----------------------------------------------------------------------------------+
|  Aircraft Tier      | Permissible Overflight          | Required Pilot Action     |
|---------------------+---------------------------------+---------------------------|
|  Class C0 / <250 g  | Uninvolved individuals allowed  | Avoid assemblies always   |
|  Class C1 (<900 g)  | NO intentional overflight       | Minimize time if overflown|
|  ALL AIRCRAFT       | Assemblies of people FORBIDDEN  | Immediate evasion/landing |
+-----------------------------------------------------------------------------------+

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Class C0 Drones & Privately Built Aircraft (< 250 g)

Class C0 represents the lightest, lowest-risk operational category in European civil aviation. Under Delegated Regulation (EU) 2019/945 (Annex Part 1), a Class C0 unmanned aircraft must comply with strict manufacturing standards:

• Maximum Take-Off Mass (MTOM): Strictly less than 250 grams (including payload, cameras, and batteries).
• Maximum Horizontal Velocity: Electronically or aerodynamically limited to 19 m/s (approximately 68.4 km/h).
• Structural Safety: Designed to minimize injury (frangible materials, rounded edges, shielded or blunt surfaces).
• Power Source: Exclusively electrical.
• Direct Remote Identification (DRI): Not required as a factory build standard (though national geographical zones may mandate broadcast capability).

Privileges and Limitations of C0 Operations

Under point UAS.OPEN.020(2), an unmanned aircraft of Class C0, or a privately built drone weighing under 250 g and flying at under 19 m/s, may be flown over uninvolved people — but never over an assembly of people.

[!IMPORTANT] Incidental vs. Targeted Overflight: While the law states that C0 drones may overfly uninvolved people, EASA's Acceptable Means of Compliance (AMC) emphasizes that good airmanship dictates avoiding unnecessary overflight of individuals whenever practicable. However, if a C0 aircraft passes directly over a pedestrian walking down a street or a homeowner in their garden, no regulatory violation occurs—provided the person is not part of an assembly of people.

Privately built drones weighing less than 250 g (with a maximum operational speed under 19 m/s) share identical operational privileges with certified Class C0 drones in Subcategory A1.

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Class C1 Drones (< 900 g or Impact Energy < 80 Joules)

Class C1 bridges consumer camera quadcopters and professional aerial platforms. Delegated Regulation (EU) 2019/945 (Annex Part 2) establishes rigorous technical requirements for Class C1 aircraft:

• MTOM & Kinetic Energy: MTOM must be strictly less than 900 grams, OR the aircraft must transfer less than 80 Joules of terminal kinetic impact energy to a human head upon impact at maximum flight speed.
• Maximum Flight Speed: Maximum level flight speed must be limited to 19 m/s, or controllable by the remote pilot.
• Direct Remote Identification (DRI): Mandatory integrated broadcast system continuously transmitting the drone operator registration number, aircraft serial number, geographical position, altitude, flight heading, and ground speed.
• Geo-Awareness System: Mandatory integrated software providing real-time awareness of published UAS geographical zones, warning the pilot when approaching restricted airspace.
• Fail-Safe Recovery: Reliable command and control (C2) lost-link recovery protocol (such as automated Return-to-Home / RTH).
• Guaranteed Sound Power Level: Maximum acoustic sound power indication displayed on the airframe packaging.

Operational Rules for C1 in Subcategory A1

The operational standard for Class C1 aircraft differs sharply from Class C0. Under point UAS.OPEN.020(1), the remote pilot of a Class C1 drone:

1. Must reasonably expect that no uninvolved person will be overflown.
2. In the event of unexpected overflight of uninvolved persons, the remote pilot shall reduce as much as possible the time during which the unmanned aircraft overflies them.

+-----------------------------------------------------------------------------------+
|                 Class C1 Flight Over Uninvolved Persons Protocol                  |
+-----------------------------------------------------------------------------------+
|   Normal Flight Plan: Steer flight path away from pedestrians and bystanders     |
|                                        │                                          |
|   Unexpected Event: Pedestrian emerges from building into flight corridor        |
|                                        │                                          |
|   Immediate Pilot Action: Adjust yaw, bank, or altitude to clear vertical profile|
|                                        │                                          |
|   Regulatory Goal: Reduce overflight duration to the absolute minimum seconds    |
+-----------------------------------------------------------------------------------+

[!WARNING] Exam Trap — C1 Fixed Standby Distances: Many exam candidates confuse Subcategory A1 with Subcategory A2. There is no mandatory 30-metre or 50-metre horizontal separation distance for Class C1 drones in Subcategory A1. You may fly close to people horizontally, but you must not fly directly over them intentionally, and you must curtail any inadvertent overflight immediately.

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The Universal Ban: What Constitutes an "Assembly of People"?

Across the entire Open category—covering Subcategories A1, A2, and A3—flying over assemblies of people is strictly prohibited under all circumstances. The universal ban sits in Article 4(1)(c) of Regulation (EU) 2019/947 and is restated for Subcategory A1 in points UAS.OPEN.020(1) and (2).

The Legal Definition (Article 2(3))

Regulation (EU) 2019/947 Article 2(3) defines an assembly of people with legal precision:

"'Assemblies of people' means gatherings where persons are unable to move away due to the density of the people present."

EASA GM1 Article 2(3) clarifies that this definition is not rooted in a specific numerical count (e.g., "more than 20 people"). Instead, it is determined by crowd density and the physiological inability to escape falling debris or an out-of-control aircraft.

+-----------------------------------------------------------------------------------+
|                       Evaluating "Assemblies of People"                           |
+-----------------------------------------------------------------------------------+
|  CRITERION: Can an individual freely step aside or run if an aircraft falls?     |
|  -------------------------------------------------------------------------------  |
|  YES -> Dispersed Uninvolved Persons (C0 overflight OK; C1 minimize overflight)   |
|  NO  -> Assembly of People (ALL DRONES STRICTLY PROHIBITED FROM OVERFLIGHT)       |
+-----------------------------------------------------------------------------------+

Concrete Examples of Assemblies of People

• Sporting events: Spectator grandstands, crowded marathon starting/finishing corridors, sideline crowds at amateur soccer matches.
• Entertainment & culture: Outdoor music festivals, open-air concerts, parades, carnivals, public firework displays.
• Civic gatherings: Political demonstrations, street rallies, picket lines, religious processions.
• Commercial & recreational hubs: High-density pedestrian shopping streets on Saturday afternoons, packed public beaches on summer weekends, crowded outdoor swimming pool lawns.

Dispersed Persons vs. Assemblies: The Critical Boundary

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Remote Pilot Competency Requirements for Subcategory A1

To ensure operational safety, Regulation (EU) 2019/947 establishes tiered competency standards for pilots operating in Subcategory A1 (Point UAS.OPEN.020(4)).

Tier 1: Class C0 and Privately Built Drones (< 250 g)

• Mandatory Training: The remote pilot must be familiar with the user manual provided by the manufacturer of the UAS.
• Exam Requirement: There is no statutory requirement under EU law to complete an online theoretical course or pass an examination to fly a C0 drone.
• Minimum Age: The standard EU minimum age is 16 years (Article 9), but Member States may lower this minimum age down to 12 years for Open category operations.
• Operator Registration: If the C0 drone is equipped with a camera or other sensor capable of capturing personal data (and is not certified as a toy under Directive 2009/48/EC), the operator must still register with the National Aviation Authority (NAA) and display their Operator ID on the aircraft.

Tier 2: Class C1 Drones (< 900 g)

• Mandatory Online Course: The remote pilot must complete an official online training course administered by or on behalf of an EASA Member State's NAA.
• Theoretical Examination: The pilot must successfully pass an online theoretical examination consisting of at least 40 multiple-choice questions distributed across the nine statutory aeronautical subjects.
• Passing Standard: Candidates must achieve at least 75% correct answers (minimum 30 out of 40 questions).
• Certificate Issued: Upon passing, the authority issues the Proof of completion of online training (commonly called the A1/A3 Certificate).
• Validity: Valid for 5 years throughout all EASA Member States (EU-27 plus Switzerland, Norway, Iceland, and Liechtenstein).

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Comparison: C0 vs. C1 vs. Privately Built Sub-250 g

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Realistic Flight Scenarios & Practical Exam Traps

Scenario A: Filming an Outdoor Wedding Reception

A pilot is hired to film an outdoor wedding with a 249-gram Class C0 drone. During the cocktail hour, 80 guests gather closely under a marquee and around the bar.

• Can the pilot fly directly over the cocktail tent?
• Regulatory Ruling: No. Because the 80 guests are clustered closely together, they cannot quickly evade a falling drone. This constitutes an assembly of people. Even with a sub-250 g C0 drone, flying directly over this gathering is illegal in the Open category. The pilot must position the drone to film from an oblique angle outside the crowd perimeter.

Scenario B: Unexpected Pedestrian in an Alleyway

A commercial pilot is using an 850-gram Class C1 quadcopter to inspect roof gutters in a historic town. A pedestrian unexpectedly steps out of a bakery doorway directly underneath the hovering drone.

• What must the remote pilot do under EU law?
• Regulatory Ruling: Under UAS.OPEN.020(1), intentional overflight is forbidden. The pilot must not maintain a hover above the pedestrian. The pilot must immediately maneuver the aircraft sideways or backwards away from the pedestrian's vertical axis, reducing the unexpected overflight time to the absolute minimum.