2.2 Subcategory A3: Flying Far from People & the 150-Metre Buffer Rule

2.2 Subcategory A3: Flying Far from People & the 150-Metre Buffer Rule

[!NOTE] Regulatory Baseline: Subcategory A3 is codified under Point UAS.OPEN.040 of Commission Implementing Regulation (EU) 2019/947. It is designated as the "fly far from people" subcategory. While Subcategory A1 relies on lightweight aircraft to minimize impact harm, Subcategory A3 relies on spatial separation to guarantee ground safety.

Subcategory A3 accommodates the heaviest aircraft permitted in the Open category, extending up to the statutory maximum of 25 kg. Because an impact from a 4 kg to 25 kg aircraft carries fatal kinetic energy, European aviation safety rules prohibit these drones from operating anywhere near populated areas, commercial complexes, or public recreational gathering sites.

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The Philosophy of Subcategory A3: Separation as Primary Risk Mitigation

The fundamental principle governing Subcategory A3 is that the operational zone must be essentially free of uninvolved people and built-up infrastructure. Rather than relying on propeller guards or frangible plastics, the safety case rests on two strict geographical boundaries:

1. A mandatory 150-metre standoff distance from residential, commercial, industrial, and recreational areas.
2. A dynamic horizontal buffer ensuring no uninvolved person is endangered within the complete operational radius of the unmanned aircraft.

+-----------------------------------------------------------------------------------+
|                         Subcategory A3 Operational Envelope                       |
+-----------------------------------------------------------------------------------+
|  Allowed Drone Classes: Class C2 (A1/A3 cert), Class C3, Class C4, Legacy 250g-25kg|
|  Separation from Built-up Areas: Minimum 150 metres horizontal standoff           |
|  Separation from People: No uninvolved person endangered (1:1 altitude rule)      |
|  Environment: Agricultural land, rural open fields, uninhabited open spaces       |
+-----------------------------------------------------------------------------------+

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Applicable Aircraft Classes & The Legacy Drone Reality

Subcategory A3 serves as the broad legal home for heavier drones and aircraft that lack specialized proximity certifications.

1. Class C2 Drones Flown Without an A2 Certificate

A Class C2 unmanned aircraft has an MTOM strictly below 4 kg. If the remote pilot holds the advanced A2 Remote Pilot Certificate of Competency (A2 CofC), they may fly in Subcategory A2 (close to people, down to 30 m or 5 m in low-speed mode). However, if the pilot holds only the basic A1/A3 certificate, they are legally restricted to flying that C2 drone exclusively in Subcategory A3, maintaining 150 m from populated areas.

2. Class C3 Drones (< 25 kg)

Class C3 covers professional heavy-lift multicopters, fixed-wing mapping platforms, and industrial camera rigs:

• MTOM strictly less than 25 kg.
• Maximum characteristic dimension (wingspan or motor diagonal) under 3 metres.
• Equipped with Direct Remote Identification (DRI), geo-awareness, and acoustic power markings.
• Class C3 drones can never fly in Subcategory A1 or A2; they are confined strictly to Subcategory A3.

3. Class C4 Drones (< 25 kg)

Class C4 is designed for traditional model aircraft and hobby aeromodellers:

• MTOM strictly less than 25 kg.
• Lacks autonomous control modes (no automated flight paths or waypoint navigation; basic flight stabilization and failsafe lost-link are permitted).
• Flown exclusively under manual control in open rural areas or designated model flying club airfields.

4. Legacy and Privately Built Drones (250 g to 25 kg)

Under Article 20 of Regulation (EU) 2019/947, all "legacy" drones (drones placed on the market without an official C0-C4 class marking) weighing between 250 g and 25 kg must be operated exclusively in Subcategory A3 after the end of the transitional period (January 1, 2024). Privately built drones in this weight category are subject to identical restrictions.

+-----------------------------------------------------------------------------------+
|                         Aircraft Classes Mapped to A3                             |
+-----------------------------------------------------------------------------------+
|  Aircraft Type          | MTOM Limit  | Competency Required | Allowed Subcategory |
|-------------------------+-------------+---------------------+---------------------|
|  Class C2 (Basic Pilot) | < 4 kg      | A1/A3 Online Exam   | Subcategory A3 ONLY |
|  Class C3               | < 25 kg     | A1/A3 Online Exam   | Subcategory A3 ONLY |
|  Class C4 (Model)       | < 25 kg     | A1/A3 Online Exam   | Subcategory A3 ONLY |
|  Legacy (250 g - 25 kg) | < 25 kg     | A1/A3 Online Exam   | Subcategory A3 ONLY |
|  Privately Built >250 g | < 25 kg     | A1/A3 Online Exam   | Subcategory A3 ONLY |
+-----------------------------------------------------------------------------------+

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The 150-Metre Standoff Rule: Defining Protected Ground Zones

Point UAS.OPEN.040(2) mandates a safe horizontal distance of at least 150 metres from four distinct categories of land use (point (1) separately requires an area where no uninvolved person is expected to be endangered):

1. Residential Areas

Includes cities, towns, villages, suburban housing developments, isolated rural hamlets, individual farmhouses, and private residential gardens. The 150-metre boundary is measured horizontally from the outermost property boundary or fence line.

2. Commercial Areas

Encompasses shopping centers, retail parks, office complexes, commercial business parks, hotels, auto dealerships, open-air markets, and active construction sites.

3. Industrial Areas

Covers manufacturing factories, chemical plants, petroleum refineries, power generation stations, electrical distribution substations, warehousing complexes, logistics freight hubs, and commercial docks.

4. Recreational Areas

Encompasses public parks, municipal sports grounds, soccer pitches, golf courses, swimming pool resorts, public camping sites, active ski slopes, marinas, and popular tourist viewing points.

[!WARNING] The "Empty Park" Exam Trap: Exam questions frequently test candidate assumptions regarding recreational areas. If an urban public park is completely empty on a freezing Tuesday morning at 06:00, a pilot STILL cannot operate a Subcategory A3 drone within 150 metres of that park. The legal restriction applies to the designation of the area, not merely the momentary presence of human beings.

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Protecting Uninvolved People: The 1:1 Rule and Dynamic Buffer Zones

In addition to the static 150-metre distance from built-up zones, UAS.OPEN.040 establishes an active requirement regarding individuals:

"Operations shall be performed in an area where the remote pilot reasonably expects that no uninvolved person will be endangered within the range where the unmanned aircraft is flown during the entire time of the UAS operation."

The 1:1 Altitude-to-Distance Rule

AMC1 UAS.OPEN.040(1) outlines the "1:1 rule" as the benchmark for maintaining safe horizontal separation from isolated uninvolved persons (such as a farmer walking across a field):

$\text{Horizontal Separation Distance} \ge \text{Current Flight Altitude}$

If the drone is flying at an altitude of 60 metres AGL, the remote pilot should maintain a horizontal separation of at least 60 metres from any solitary uninvolved person. If the aircraft climbs to 120 metres, the horizontal standoff buffer expands to 120 metres.

          [Drone at 100 m AGL]
                 /|
                / |
  Glide/Fall   /  | Flight Altitude = 100 m
  Trajectory  /   |
             /    |
            /     |
[Uninvolved Person] ─── Horizontal Standoff Buffer >= 100 m ─── Ground Zero

Minimum Absolute Buffer

Even when flying at very low altitudes (e.g., 10 m AGL), the pilot should maintain a minimum physical standoff of at least 30 metres from any uninvolved person to account for potential GPS drift, wind gusts, or pilot reaction delay.

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Operating Envelopes: Rural Farmland vs. Suburban Encroachment

To conduct legal Subcategory A3 flights, remote pilots must seek out genuinely unpopulated geographical sectors:

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Role of the A1/A3 Certificate in Subcategory A3

The Proof of completion of online training (the standard A1/A3 certificate) is the legal key that unlocks Subcategory A3 operations across Europe. Without this credential, an operator cannot legally fly any drone weighing 250 grams or more in the Open category.

Unlocking Heavy Drone Privileges

By earning the A1/A3 certificate, a remote pilot acquires the legal authority to fly:

• Advanced enterprise inspection platforms (e.g., 9 kg industrial hexacopters) in agricultural fields.
• Heavy cinematography rigs (up to 25 kg MTOM) on isolated rural film sets.
• Large model aeroplanes (Class C4 or legacy model aircraft) at designated unpopulated fields.

All of these operations share the same mutual recognition across all 27 EU Member States, Iceland, Liechtenstein, Norway, and Switzerland for a period of 5 years.