SORA – Specific Operation Risk Assessment

Specific Operations Risk Assessment (SORA) is a method to decide the risk of a UAS operation. The method contains ten steps.

  1. Make a concept of operations document (ConOps). A ConOps describes the UAS and the operations to be flown.
  2. Decide intrinsic Ground Risk Class (GRC). This is a classification of the risk that the drone will hit a person on the ground. It is indicated with a number from one to seven.
  3. Decide final GRC after risk-reducing measures have been taken. Measures can, for example, be buffer zones, parachutes, and if an emergency response plan (ERP) is in place. 
  4. Decide initial Air Risk Class (ARC). This is a classification of the risk of hitting another aircraft. The risk is classified with a letter ranging from A to D.
  5. Decide residual ARC. This can be done if the actual traffic in the airspace is lower than what the initial ARC classification implies. It can also be done by using standard rules and structures as mitigating measures.
  6. Make sure that Tactical Mitigations Performance Requirements (TMPR) are satisfied. These requirements are measures to mitigate the risk of in-air collisions. The requirements are derived from the ARC.
  7. Decide Specific Assurance and Integrity Level (SAIL). This value is derived from the final GRC and residual ARC. 
  8. Identify Operational Safety Objectives (OSOs). These are derived from the SAIL value and define requirements for technical systems, training and procedures.
  9. This step is about considering the risk for nearby areas and airspace in case of a fly-away. Requirements can be found in the AMC from EASA.
  10. Create a safety portfolio that describes the following:
    ·  How risk is reduced for GRC and ARC.
    ·  How TMPR is satisfied.
    ·  How the OSOs are satisfied.

More information regarding the SORA process can be found in Easy Access Rules for Unmanned Aircraft Systems (Regulations (EU) 2019/947 and(EU) 2019/945).