6.3 Site Survey, Assemblies of People & Incident Reporting

Site Survey, Assemblies of People & Incident Reporting

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Operational Site Survey & Ground Risk Evaluation

Before deploying a UAS in subcategory A2, the remote pilot is legally obligated under UAS.OPEN.060 to conduct a thorough pre-flight evaluation of the operating environment.

1. Systematic Identification of Ground Hazards

The remote pilot must survey the operational volume and surrounding buffer zones for high-risk surface features:

• Active Transportation Corridors: Highways, motorways, railway lines, and tram tracks. Operating adjacent to fast-moving vehicular traffic presents severe secondary hazards. A falling aircraft or sudden driver distraction can cause high-speed multi-car pileups or derailments.
• Overhead High-Voltage Infrastructure: Transmission towers, distribution lines, and railway catenary wires. High-voltage power lines present two distinct risks: physical collision hazards (thin conductor cables are difficult to detect against urban backgrounds) and strong electromagnetic fields (EMF) that can induce severe compass and IMU sensor errors.
• Industrial & Hazardous Material Sites: Chemical manufacturing facilities, fuel depots, petrol stations, and gas transfer pipelines, where an impact with an ignited LiPo battery could cause an explosion.
• Sensitive Receptors: Hospitals with emergency helipads, schools, kindergartens, prisons, and nature protection reserves where flight restrictions may apply.

2. Establishing Take-Off and Landing Areas (TOLA)

A professional A2 operation requires pre-designating three levels of landing zones:

[ Primary TOLA ] ------> Pre-briefed, secured 3-5 m radius, clean flat surface
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        v
[ Alternate TOLA ] ----> Secondary clear site if primary is obstructed by public
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        v
[ Emergency Landing ] -> Pre-scouted soft terrain (turf, bushes) for forced ditching

• Primary TOLA: A clear, flat, level surface with a secured perimeter of at least 3 to 5 m. The ground should be free of loose gravel, sand, or dry leaves that could be sucked into motor air gaps or propelled outward by propeller wash. It must have an unobstructed upward departure and approach cone free of overhanging tree branches or cables.
• Alternate TOLA: A designated secondary landing area ready for immediate use if the primary TOLA becomes compromised (e.g., parked vehicles, curious bystanders, or maintenance workers).
• Emergency Forced-Landing Spots: Pre-scouted locations (e.g., open lawns, unoccupied sports pitches, or soft vegetation) along the flight corridor where the pilot can intentionally crash-land the aircraft if a critical malfunction occurs, preventing damage to structures or injury to people.

3. Visual Line of Sight (VLOS) Analysis

The remote pilot must maintain continuous, unaided visual contact with the aircraft to monitor its flight path and scan surrounding airspace for conflicting traffic. During the site survey, the pilot must identify potential line-of-sight shadow zones caused by high-rise building corners, dense foliage, or terrain contours, ensuring the flight plan never places an obstacle between the pilot and the drone.

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Assemblies of People: The Absolute Ban in Open Category

Under Regulation (EU) 2019/947, Article 2(3), an assembly of people is defined as:

"Gatherings where persons are unable to move away due to the density of the people present."

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The Core Test: Escape and Mobility

The legal test for an assembly of people is not raw head count. It is density and the physical inability of individuals to escape freely. If a multirotor loses power or sheds a rotor over a crowd, people packed shoulder-to-shoulder cannot run, step aside, or dive for cover. Falling debris will inevitably strike someone.

Concrete Examples of Assemblies of People

• Concerts, Festivals & Outdoor Rallies: Music festivals, political rallies, open-air stages;
• Sporting Events: Spectators along marathon routes, cycling finish lines, football stadiums, or golf gallery crowds;
• Crowded Public Spaces: Beaches or parks on a sunny day, commercial streets while the shops are open, busy open-air and Christmas markets, and ski resorts and slopes (GM1 Article 2(3) lists several of these as examples);
• Transit Hubs: Crowded outdoor platforms or queuing areas outside major train stations or ferry terminals.

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In-Flight Contingency Management & Emergency Procedures

When anomalies occur during an A2 operation, the remote pilot must execute pre-programmed, practiced contingency procedures:

1. Incursion of Uninvolved Persons into the Safety Buffer

• Immediate Control Input: Immediately release position sticks to arrest all forward progress;
• Climb or Translate Away: If height allows, climb vertically or translate laterally into unoccupied airspace to re-establish the legal 30 m (or 5 m) buffer;
• Never Descend Toward People: Do not initiate a descent if individuals are underneath or walking toward the landing zone; descending increases relative closure rate and blade strike severity.

2. Command and Control (C2) Link Loss

• Cause: Radio-frequency (RF) shadowing behind concrete/steel buildings, high-power directional microwave links, or electromagnetic interference;
• Automated Failsafe Activation: Modern Class C2 drones automatically initiate failsafe procedures (hover, climb-to-return, and Return-to-Home [RTH]).
• Pre-Flight RTH Altitude Setting: During pre-flight preparation, set the failsafe RTH altitude comfortably above the tallest obstacle on any possible return path (many operators add 15 to 20 m). If RTH is set to 30 m and a building along the return vector is 45 m tall, the drone will fly into the building structure upon signal loss!

3. Flyaway or Uncommanded Flight (Sensor Fusion Anomaly)

• Cause: Magnetic compass distortion caused by flying too close to steel-reinforced concrete or buried metallic infrastructure, leading to conflicting sensor data between the compass and GNSS receiver (toilet-bowling or rapid uncommanded acceleration);
• Immediate Pilot Action: If the aircraft offers it, switch from GNSS / positioning mode to manual / attitude (ATTI) mode (some drones drop into it automatically). Switching to ATTI mode cuts off automated satellite position corrections, allowing the pilot to manually level the aircraft, counteract wind drift, and fly back to safety.
• Flight Termination System (FTS): If the aircraft is completely unresponsive to stick inputs and is accelerating uncontrollably toward uninvolved persons, active traffic, or an assembly of people, activate the emergency Flight Termination System (FTS / motor stop / kill switch) immediately to ground the aircraft before it gains excessive kinetic energy or altitude.

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Incident & Occurrence Reporting (Regulation (EU) No 376/2014)

Under Article 19 of Regulation (EU) 2019/947 and Regulation (EU) No 376/2014, aviation safety in the European Union relies on a harmonized Mandatory Occurrence Reporting (MOR) system.

The Mandatory 72-Hour Reporting Window

The UAS operator or remote pilot must submit a formal occurrence report to the competent authority (normally the national aviation authority; follow its reporting instructions) within 72 hours of becoming aware of the occurrence.

[ Incident Occurs ]
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[ Secure Site & Render Aid ]
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[ Evaluate Mandatory Reporting Criteria ]
        |---> Fatal or serious personal injury?
        |---> Manned aircraft conflict or near-miss?
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        +--- YES ---> Submit Formal MOR to NAA within 72 HOURS!
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        +--- NO  ---> Log it; consider a voluntary report

What Constitutes a Mandatory Reportable Event?

For UAS operations that need no certificate or declaration, which covers the whole open category, Article 3(2) of Regulation (EU) No 376/2014 limits mandatory reporting to occurrences that (as GM1 Article 19(2) explains):

1. Fatal or Serious Injury to a Person:
   • Under European aviation law, a "serious injury" includes any injury requiring hospitalization for more than 48 hours, commencing within 7 days of the event; bone fractures (excluding simple fractures of fingers, toes or the nose); injury to any internal organ; severe lacerations causing extensive nerve, muscle, or tendon damage; or second- or third-degree burns.
2. Involvement of Manned Aircraft:
   • Any collision, airprox (near-miss), or situation where a manned aircraft crew had to take evasive collision-avoidance maneuvers due to the presence of the UAS;
   • In short, any occurrence that involved an aircraft other than an unmanned one.

Other events, such as a crash into property, an infringement of a geographical zone or a flyaway with no injury and no manned aircraft involved, fall outside this mandatory limit. They may still have to be reported under other national laws (for example to the police or for property damage), and they can be submitted as voluntary occurrence reports.

Voluntary Occurrence Reporting (VOR) & Safety Culture

Incidents that fall below the mandatory threshold (e.g., minor propeller clip against a tree branch during landing, bird dive-bombing without damage, temporary GPS loss recovering safely) should still be logged in the operator's internal flight log, and can be reported voluntarily to the competent authority under Regulation (EU) No 376/2014. Recording near-misses fosters an open Just Culture, allowing operators and flight academies to identify operational risks and refine safety checklists before serious accidents occur.