Strategic Application of Mitigations: Phase 5 in SORA Knowledge Series
In our previous discussion on Step 4 of SORA: Initial Air Risk Class (ARC) Determination, we dived into the nitty-gritty of assessing potential air risk. Now, let's move on to Step 5, focusing on the application of strategic mitigations to minimize the likelihood of mid-air collisions.
This crucial step is all about creating a safer flying environment for drones and making sure we remain in regulatory compliance. Strategic mitigations are proactive measures taken before the flight to limit exposure to risk, either through operational restrictions or the use of airspace structures and rules.
So, what are these strategic mitigations all about?
Strategic mitigations are pre-flight measures aimed at lowering the probability of a UAS (Unmanned Aerial System) encountering a manned aircraft in the operational airspace. These mitigations adjust the Initial ARC and result in a Residual ARC, which determines the necessary level of tactical mitigations in subsequent steps.
Strategic mitigations can be divided into two main categories:
- Operational Restrictions - Directly controlled by the UAS operator.
- Common Airspace Structures and Rules - Controlled by the Competent Authority or ANSP (Air Navigation Service Provider) and applicable to all airspace users.
Operational Restrictions - Taking matters into our own hands
Operational restrictions are mitigation strategies that limit the operational exposure of the UAS, thereby reducing the likelihood of encounters with manned aircraft. These mitigations include:
1. Geographical boundaries
- Constraining the operational volume to specific areas with minimal manned aircraft operations.
- Avoiding high-density airspace such as airport control zones or busy flight corridors.
- Flying in segregated or restricted airspace to minimize collision risk.
2. Time-based restrictions
- Restricting operations to specific periods when manned air traffic density is lower.
- Performing night-time operations in airspaces where manned aircraft predominantly operate during the day.
3. Limiting time of exposure
- Reducing the total operational duration within airspace where manned aircraft operate.
- Minimizing transition time in high-risk areas, such as flying a shorter route through controlled airspace.
Common Airspace Structures and Rules - Official measures to ensure safety
Unlike operational restrictions, common structures and rules apply to all aircraft within a given airspace and are enforced by authorities like ANSPs or U-Space providers.
1. Common Flight Rules
- Right-of-way rules that establish priority between manned and unmanned aircraft.
- Requirements for electronic conspicuity, such as ADS-B transponders.
- Mandatory flight planning and submission to a central ANSP system.
2. Common Airspace Structures
- Designated UAS corridors to separate drone traffic from manned aircraft.
- Predefined airways or procedural routes for safer integration.
- Mandatory participation in UTM/U-Space services, ensuring dynamic air traffic awareness.
Lowering the Initial ARC Using Strategic Mitigations
The Initial ARC is assigned based on Airspace Encounter Categories (AECs), which define operational environments and their respective air traffic densities. The ARC can be lowered through strategic mitigations by demonstrating that the local air traffic density is lower than the generalized risk assumptions.
Understanding the AEC and Density Rating
- The AEC classification assigns a density rating to airspace based on the probability of encountering manned aircraft.
- Density ratings range from 1 (low) to 5 (very high).
- The Initial ARC is based on these ratings and can be found in standardized tables.
Steps to Lower the Initial ARC
- Identify the AEC applicable to the operation (e.g., operating near an airport, in uncontrolled rural airspace, in segregated airspace, etc.).
- Determine the initial ARC based on the AEC and generalized air traffic density rating.
- Apply strategic mitigations to justify a lower local air density rating, such as:
- Operating in a restricted time window when fewer manned aircraft are present.
- Using airspace segregation or pre-coordination with ATC/ANSP.
- Providing traffic studies, radar data, or operational assessments to validate reduced encounter rates.
- Submit evidence to the Competent Authority for approval of the adjusted ARC level.
What If Strategic Mitigations Are Not Enough?
If strategic mitigations alone do not sufficiently reduce the ARC, operators will need to apply tactical mitigations (Step 6), such as:
- Detect and Avoid (DAA) systems.
- UTM-based conflict resolution tools.
- Real-time pilot intervention measures.
Wrapping Up
Step 5 of the SORA process helps operators implement strategic mitigations to proactively manage air risks before flight. By strategically applying operational restrictions and common airspace structures, operators can potentially lower the required safety measures in subsequent steps.
Stay tuned for our next blog, where we delve into Step 6 of SORA: Tactical Mitigations and Detect & Avoid Requirements!
Need help with your SORA application? Contact our website Consultancy for expert guidance on navigating the SORA process and ensuring compliance with UAS regulations.
- In Step 5 of the SORA process, operators are tasked with implementing strategic mitigations to manage air risks before a flight.
- Strategic mitigations are pre-flight measures aimed at decreasing the likelihood of UAS encounters with manned aircraft in the operational airspace.
- Operational restrictions and common airspace structures are the two main categories of strategic mitigations.
- Operational restrictions include geographical boundaries, time-based restrictions, and limiting time of exposure, aimed at reducing operational exposure of UAS to manned aircraft.
- Common airspace structures and rules, enforced by authorities like ANSPs or U-Space providers, include common flight rules and common airspace structures for safer integration.
- By strategically applying operational restrictions and common airspace structures, operators can potentially lower the required safety measures in subsequent steps, ensuring safety, regulatory compliance, and effective UAS operations.
