Assessing Risk in UK Drone Operations: The New UK SORA Methodology

The expanding role of Unmanned Aircraft Systems (UAS) in the United Kingdom has driven a significant update to how operational risks are assessed, particularly for drones in the Specific category. The UK Civil Aviation Authority (CAA) is transitioning from the traditional Operating Safety Case (OSC) approach to the UK Specific Operations Risk Assessment (UK SORA) methodology. This shift, detailed in newly updated documents—CAP 722 (Edition 10, Amendment 1), CAP 722A, CAP 3017, ORS9 CAA Decision No. 46, and CAP 722B (Edition 5)—introduces a more systematic and quantifiable framework for drone operations. Set to take effect on 23 April 2025, UK SORA aims to enhance safety and consistency. This article explores how risk is calculated under this methodology, its core components, and its implications for UK drone operators.

From OSC to UK SORA: A Regulatory Evolution

Historically, the CAA relied on the OSC process, outlined in CAP 722A (Unmanned Aircraft System Operations in UK Airspace – Operating Safety Cases), to evaluate risks for Specific category operations—those exceeding the low-risk Open category but not reaching the complexity of the Certified category. This approach required operators to submit detailed safety cases for individual review. While effective, it was often criticised for its subjectivity and lengthy approval times, as noted in the latest updates to CAP 722A, which confirm its withdrawal on 23 April 2025.

In its place, the CAA has introduced UK SORA, adapting the Joint Authorities for Rulemaking on Unmanned Systems (JARUS) SORA v2.5 framework to UK needs. This transition is formalised in CAP 722 (Unmanned Aircraft System Operations in UK Airspace – Guidance & Policy), updated to Edition 10, Amendment 1 on 10 December 2024, and detailed in CAP 3017 (UK Specific Operations Risk Assessment Methodology), released on the same date. ORS9 CAA Decision No. 46, also published on 10 December 2024, establishes UK SORA as an Acceptable Means of Compliance (AMC) to UK Regulation (EU) 2019/947 Article 11, with full implementation scheduled for 23 April 2025. Additionally, CAP 722B (Remote Pilot Competence), updated to Edition 5, supports this shift by introducing new training standards effective immediately.

How UK SORA Calculates Risk

UK SORA, as outlined in CAP 3017, follows a 10-step process to assess risks, implement mitigations, and define safety standards. Unlike the narrative-heavy OSC, it employs measurable metrics for a consistent approach. Here’s how it works:

1. Defining the Concept of Operations (ConOps)

   
   

   The process begins with a detailed ConOps, specifying the operation’s purpose, drone specifications, operational environment, and personnel involved. CAP 722 (Section 2) underscores this as the foundation for identifying risk factors.

   
   

2. Determining the Intrinsic Ground Risk Class (GRC)

   
   

   Ground risk evaluates the potential harm of a drone crash to people or property. UK SORA assigns a GRC score (1–7) based on the drone’s kinetic energy—derived from mass and speed—and the area’s population density. A lightweight drone over a rural area scores lower than a heavier one above an urban centre.

   
   

3. Evaluating Air Risk Class (ARC)

   
   

   Air risk assesses the chance of colliding with manned aircraft. The ARC (a–d) is calculated using airspace type, traffic density, and proximity to aerodromes, with guidance drawn from CAP 722.

   
   

4. Applying Mitigations and Adjustments

   
   

   Operators can lower GRC and ARC scores with mitigations like geofencing or enhanced training, as detailed in CAP 3017. Each measure’s effectiveness (low, medium, high) must be evidenced to adjust the risk profile.

   
   

5. Setting the Specific Assurance and Integrity Level (SAIL)

   
   

   The adjusted GRC and ARC determine the SAIL (I–VI), reflecting the operation’s overall risk. Higher SAIL levels, as per CAP 3017, require stricter safety measures, such as redundant systems.

   
   

6. Establishing Operational Safety Objectives (OSOs)

   
   

   Finally, UK SORA sets OSOs—specific, verifiable safety requirements—based on the SAIL. These, outlined in CAP 3017, cover equipment, procedures, and emergency responses to keep risks acceptable.

   
   

Supporting this, CAP 722B introduces updated Remote Pilot Competence (RPC) standards, effective from 10 December 2024, ensuring pilots meet the training levels required for UK SORA operations.

Implications for Operators

For drone operators, UK SORA offers a clearer, more predictable process, as highlighted in ORS9 CAA Decision No. 46. Its data-driven approach, detailed in CAP 3017, reduces ambiguity, aiding planning and approvals from 23 April 2025. However, it demands technical proficiency and compliance with new standards, including those in CAP 722B. While larger operators may adapt quickly, smaller businesses might face challenges, though the CAA plans support via the UK SORA Application Service, launching on 23 April 2025, and updated guidance in CAP 722.

Looking Forward

The shift to UK SORA, cemented by the 10 December 2024 releases of CAP 722, CAP 3017, ORS9 CAA Decision No. 46, and CAP 722B, marks a maturing UK drone sector. From 23 April 2025, as CAP 722A’s OSC fades out, this methodology will standardise Specific category approvals. It’s a rigorous yet practical framework, balancing safety with the industry’s growth, and operators will need to align with its requirements to thrive in this evolving landscape.