Specific Operation Risk Assessment (SORA)

Last update

  • The operational risk assessment required for an operation in the SPECIFIC category may be conducted using the SORA methodology.
  • SORA
    • This methodology is a risk-based method to evaluate and manage the UAS operational risk
    • This evaluation is based on the UAS ConOps, associated ground and air risk
  • When submitting a SORA, the operator has to obtain an operational authorization from DAC to be able to start its operations.
  • What documents are needed when submitting an application for an operational authorization using the SORA methodology?
    • The DAC-UAS forms 401/402/403;
    • The operational manual (OM);
    • The risk assessment or safety portfolio of your intended operation, and;
    • Any documents to support their application;

1 – Concept of Operation

The ConOps or Concept of Operation is divided in two parts:

  • The operational part that covers your organization overview, the type of your operation(s) and the procedures, your crew and its training.
  • The technical part that covers your UAS design and architecture.

2 – The intrinsic GRC (Ground Risk Class)

The ground risk buffer applies only on the ground and is part of the ground risk model.
The dimension of your ground risk model should first be defined:

  • The geographical area of flight will depend on area needed for your operation;
  • The contingency area will depend on the speed of your operation and the Remote Pilot reaction time for the activation of the contingency procedures;
  • The ground risk buffer will depend on the method chosen to determine it (e.g. the rule 1:1, the ballistic approach, the tether length…)

The intrinsic GRC is determined according to 4 criteria:

  • The size of your UAS
  • The typical energy expected during an impact in case of crash
  • The line of sigh for the remote pilot 
  • The density of people overflown

3 – The final GRC (Ground Risk Class)

The above mentioned intrinsic GRC can be lowered (mitigated), to obtain the final GRC, through:

  • Operational procedures (controlled ground area, ERP…)
  • Additional UAS equipment (E.g. Parachute)

4 – The initial ARC (Air Risk Class)

The dimension of your air risk model should first be define:

  • The geographical flight area  will depend on maximum height for your operation;
  • The contingency volume will depend on the vertical speed of your operation and the Remote Pilot reaction time for the activation of the contingency procedures;
  • The air risk buffer will depend on the method chosen to determine it (e.g. the rule 1:1, the ballistic approach, the tether length…)

The initial ARC (Arc-a-low to Arc-d-high) is established according to:

  • The height of the UAS (under or above 120m)
  • The airspace classification (controlled or uncontrolled)
  • The line of sight of the RP (VLOS/BVLOS)

5 – The Strategic mitigation (residual Air Risk Class)

The above mentioned initial ARC can be lowered (mitigated), to obtain the residual ARC, through:

  • Strategic mitigation by operational restrictions, and/or
  • Strategic mitigations by the application of common structures and rules

For all operation below 120m (400ft), the Geoportal provides the procedures that need to apply.

6 – The TMPR and robustness level

Tactical Mitigation Performance Requirement are applied to lower (mitigate) any residual risk of a mid-air collision.

  • For operation under VLOS/EVLOS, the tactical mitigation can be:
    • The use of a Visual Observer,
    • Development of a Phraseology (crew/crew, RP/VO…)
    • Procedures (de-confliction scheme)
  • For operation under BVLOS, the tactical mitigation can be:
    • Use of a Detect And Avoid system,
    • ATC separation services,
    • U-space …

7 – Safety Assurance Integrity Level (SAIL)

The SAIL is generated from the final GRC and the ARC (initial or residual) and represents the required level of confidence that the UAS operation will stay under control. 

8 – Operational Safety Objectives (OSOs)

The SAIL is linked to the OSOs and determines the related level of each OSO that needs to be achieved. The “SORA checklist” document will help the operator by identifying the level of the 24 OSOs according to the obtained SAIL. For each OSOs of each SAIL, the operator must reply to the level of compliance of each OSOs. There are 3 level of OSOs :

  • LOW: the operator declares the compliance (the supporting evidence should be available and can be request by the DAC);
  • MEDIUM: the operator declares the compliance and systematically provides supporting evidences;
  • HIGH: the operator asks validation from a competent third party (depending on the subject: EASA…).

9 – Adjacent Area/Airspace

This step aim to assess/analyze the adjacent area and airspace, in case a loss of control.

The operator has two solutions and he/she can either apply:

  • Basic containment
  • Enhanced containment

10 – Safety Portfolio

The comprehensive safety portfolio is the SORA submitted to the DAC. It has to contain the following information:

  • The intrinsic GRC determination,
  • Mitigations used to lower the Intrinsic GRC
  • The initial ARC determination
  • Strategic Mitigation for the Initial ARC
  • Tactical mitigation for the Residual ARC
  • The SAIL and OSOs determination
  • Adjacent area/airspace considerations
  • All other supporting documents 

Organisation

Directorate of Civil Aviation