Risk Assessment (SORA)

Introduction

Safety is the cornerstone of all unmanned aircraft system (UAS) operations. For drone pilots operating in the Specific category under the European Union Aviation Safety Agency (EASA) framework, performing a robust risk assessment is not optional—it’s a legal requirement. The Specific Operations Risk Assessment (SORA) methodology provides a systematic approach to evaluating risks and ensuring safe operations. This lesson will guide you through the essentials of SORA, including Ground Risk Class (GRC) and Air Risk Class (ARC) determination, Operational Safety Objectives (OSO), and the process of creating a complete risk assessment for your operations.

Understanding and applying SORA is crucial for drone pilots, as it enables compliance with EASA regulations, ensures safety for people and property, and supports professional and responsible drone operations.

SORA Methodology Overview

SORA (Specific Operations Risk Assessment) is a standardized process designed to assess the risks associated with UAS operations and determine appropriate mitigation measures. It is primarily used for operations that fall under the Specific category, where risks exceed those in the Open category but are not as complex as those in the Certified category.

The SORA methodology consists of the following steps:

1. Define the operational concept: Outline your intended operation, including location, altitude, and type of drone.
2. Determine the Ground Risk Class (GRC): Evaluate the risk to people and property on the ground.
3. Determine the Air Risk Class (ARC): Assess the risk to other airspace users.
4. Apply mitigation measures: Identify and implement strategies to reduce risks.
5. Achieve Operational Safety Objectives (OSO): Meet specific safety requirements based on the risk levels.
6. Validate the operation: Ensure all mitigations are effective and the operation complies with regulations.

SORA allows operators to tailor their risk assessments to the specific nature of their operations, ensuring a flexible yet comprehensive approach to safety.

Ground Risk Class (GRC) Determination

Ground Risk Class (GRC) assesses the risk posed by your operation to people and property on the ground. GRC is influenced by factors such as:

• Operational environment: Whether you are operating in populated, sparsely populated, or unpopulated areas.
• Drone characteristics: Weight, size, and kinetic energy of the UAS.
• Type of operation: VLOS (Visual Line of Sight) or BVLOS (Beyond Visual Line of Sight).

Steps to Determine GRC

1. Identify the environment: Classify the area of operation as urban, rural, or unpopulated.
2. Calculate intrinsic GRC: Use predefined tables in SORA documentation (Reg 2019/947 Annex D) to determine the base GRC based on your drone's weight and operation type.
3. Apply mitigations: Reduce GRC by implementing measures such as limiting flight altitude, using geo-fencing, or deploying parachutes.

Example Scenario:

You are planning a BVLOS operation with a drone weighing 5 kg over a rural area. The intrinsic GRC is 5 based on SORA tables. By implementing mitigations like maintaining a low flight altitude and ensuring controlled takeoff and landing zones, you can reduce the GRC to 3.

Air Risk Class (ARC) Determination

Air Risk Class (ARC) evaluates the risk posed to other airspace users during your operation. It is influenced by:

• Airspace category: Controlled or uncontrolled airspace.
• Proximity to airports: Operations near airports increase the ARC.
• Altitude: Higher altitudes generally pose more risk to manned aviation.

Steps to Determine ARC

1. Identify airspace characteristics: Determine if the operation is in controlled or uncontrolled airspace.
2. Calculate intrinsic ARC: Refer to SORA documentation to assign an ARC value based on airspace and operational parameters (Reg 2019/947 Art. 11).
3. Apply mitigations: Reduce ARC by implementing measures such as airspace coordination, real-time traffic monitoring, or equipping your drone with detect-and-avoid systems.

Example Scenario:

You plan to operate in uncontrolled airspace at 80 meters altitude. The intrinsic ARC is 2. By notifying local aviation authorities and equipping your drone with a transponder, you can reduce the ARC to 1.

Operational Safety Objectives (OSO)

Operational Safety Objectives (OSO) are specific measures that must be implemented based on the GRC and ARC of your operation. These objectives are designed to ensure your operation achieves an acceptable level of safety.

Key OSO Examples:

• OSO #1: Establish robust procedures to ensure operational control, including pre-flight checks and communication protocols.
• OSO #5: Equip the drone with fail-safe systems, such as return-to-home functionality.
• OSO #10: Train remote pilots to meet competency standards (Reg 2019/947 Annex A).

Practical Implementation:

For a high-risk operation (e.g., GRC 6 and ARC 3), you may need to implement advanced OSOs such as redundancy in critical systems, real-time traffic monitoring, and pilot certification.

Creating a Risk Assessment for Operations

To create a complete risk assessment using SORA, follow these steps:

1. Define the operation: Describe your mission, including location, type of drone, and operational parameters.
2. Evaluate risks: Calculate GRC and ARC based on the environment and airspace characteristics.
3. Identify mitigations: Implement strategies to lower GRC and ARC values.
4. Apply OSO: Ensure all required safety measures are in place.
5. Validate the assessment: Review the risk assessment to ensure compliance with EASA standards (Reg 2019/947 Art. 8).

Example Scenario:

You plan a BVLOS operation with a 10 kg drone in controlled airspace over a sparsely populated area.

• GRC determination: Start with GRC 6, reduce to GRC 3 by using parachutes and limiting altitude.
• ARC determination: Start with ARC 3, reduce to ARC 2 by coordinating with air traffic control.
• OSO application: Implement OSO for operational control, pilot training, and fail-safe systems.

Key Takeaways

• SORA is mandatory for operations in the Specific category: It ensures safety and compliance with EASA regulations.
• Ground Risk Class (GRC) evaluates risks to people and property on the ground and can be mitigated through operational measures.
• Air Risk Class (ARC) assesses risks to other airspace users and can be reduced with airspace coordination and technology.
• Operational Safety Objectives (OSO) provide a structured framework for implementing safety measures tailored to your operation.
• Creating a risk assessment involves defining the operation, evaluating risks, applying mitigations, and validating compliance.

By mastering SORA, drone pilots can confidently conduct safe and compliant operations while minimizing risks to the ground and airspace.