Key Considerations for BVLOS Visual Mitigation in a UK Regulation (EU) 2019/947 Compliant Operating Safety Case (OSC)

As the demand for Beyond Visual Line of Sight (BVLOS) operations grows, drafting a UK Civil Aviation Authority (CAA)-compliant Operating Safety Case (OSC) becomes a critical step for drone operators. Under UK Regulation (EU) 2019/947, achieving BVLOS permissions requires a thorough demonstration of risk mitigation and operational safety. One crucial component is visual mitigation (VM), which ensures that the operational area remains safe from hazards when the drone is flown beyond the pilot’s direct line of sight. In this article, we delve into the key considerations for BVLOS visual mitigation and highlight what the CAA is looking for in a compliant OSC.

1. Clearly Define within the OSC the Operational Area (Operational Volume)

The first step in any OSC is to define the operational area in precise terms. For BVLOS VM, this means providing:

• A detailed map showing the flight area and its surroundings.

• Identification of potential ground and air risks, such as residential zones, infrastructure, and controlled airspace.

• Specifics about any known obstacles (e.g., buildings, towers, or vegetation).

  
  

The CAA expects operators to demonstrate a clear understanding of where the drone will be flying and the associated risks within that airspace.

2. Use of Visual Observers (VOs)

In BVLOS operations, visual observers play a crucial role in maintaining situational awareness. The OSC should describe:

• The placement and number of VOs along the flight path.

• Their specific duties, such as identifying potential intrusions or hazards.

• How they communicate with the Remote Pilot in Command (RPIC).

• Any tools provided to assist them, such as binoculars or real-time drone telemetry.

  
  

The CAA will look for clear evidence that VOs are adequately trained and equipped to fulfil their role effectively.

3. Technical Aids for Visual Mitigation

Beyond human observation, the OSC should detail any technical systems used to enhance situational awareness. These could include:

• Detect-and-avoid (DAA) systems to identify other air traffic.

• Ground-based radar or electronic conspicuity systems.

• Geo-awareness tools and airspace management platforms.

  
  

These technologies should be described in detail, including how they integrate into the overall safety framework and how they are monitored in real-time.

4. Contingency and Emergency Procedures

The CAA places significant emphasis on how operators plan for the unexpected. Your OSC must clearly articulate:

• Procedures for lost communication or link failures.

• Actions to be taken in the event of an airspace incursion or ground hazard.

• Safe recovery procedures to minimise risk to third parties.

  
  

These plans should be rehearsed and validated through simulations or test flights, with the findings included in the OSC.

5. Human Factors and Training

Strong BVLOS operations rely on well-trained personnel. The OSC should provide evidence of:

• Initial and ongoing training programmes for the RPIC, VOs, and other team members.

• Procedures to assess and mitigate human factors such as fatigue, workload, and situational awareness.

• How competency is evaluated and maintained, particularly for BVLOS-specific tasks.

  
  

The CAA will expect a clear link between training and operational safety, supported by robust records and documentation.

6. Risk Assessment and CAP 722A Volume 3 Methodology

In the UK, the CAP 722A Volume 3 methodology is used as the framework for conducting risk assessments for BVLOS operations. The OSC should:

• Identify Ground and Air Risks: Provide a detailed analysis of the operational environment, identifying potential hazards to people, property, and other airspace users.

• Implement Risk Mitigation Measures: Clearly outline the strategies and tools used to mitigate identified risks. This could include separation buffers, technical aids like electronic conspicuity, or operational procedures such as time-of-day restrictions.

• Demonstrate an Acceptable Level of Safety (ALoS): Use qualitative and quantitative methods to show that the residual risk after mitigations is acceptable. For example, include data from flight trials, simulations, or historical operations to support your conclusions.

• Engage in Iterative Risk Analysis: CAP 722A advocates an iterative approach to risk assessment, where findings from operations are continuously reviewed and updated to improve safety measures. Ensure your OSC reflects this dynamic process.

  
  

The CAP 722A methodology also encourages operators to document assumptions and limitations, ensuring that the safety case remains transparent and credible. Providing a structured and detailed approach in this section will demonstrate your commitment to meeting CAA standards.

7. Data-Driven Evidence

Regulators value evidence-based decision-making. Support your visual mitigation strategy with:

• Data from previous flights or trials.

• Logs demonstrating the effectiveness of technical aids.

• Feedback and evaluations from VOs and other personnel.

  
  

Providing tangible evidence helps to build trust and confidence in your proposed operation.

8. Engagement with Stakeholders

Finally, demonstrate proactive engagement with relevant stakeholders. This could include:

• Local air traffic control (ATC) units.

• Landowners and local authorities.

• Emergency services or other organisations operating in the area.

  
  

Document these engagements in your OSC to show that all parties have been considered and consulted where necessary.

Writing a compliant OSC for BVLOS operations under UK Regulation (EU) 2019/947 is no small task. By focusing on clear definitions, robust visual mitigation strategies, and evidence-backed risk management, you can meet the CAA’s stringent requirements. Remember, the CAA’s ultimate priority is public safety, so ensure your OSC reflects a thorough, methodical approach to identifying and mitigating risks.

With careful planning and attention to detail, your BVLOS application can pave the way for safe and innovative drone operations in the UK.

If you would like some help, why not consider our OSC authoring service? To find out more call us on 01353 880988 or email info@