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Specific Operations Risk Assessment for Drone Operators

Updated: Feb 4, 2019

What is a SORA risk analyses and how can it help you in setting up an Operating Manual for your drone operation in the Specific Category?


The Specific Operations Risk Assessment (#SORA) was developed by JARUS (the Joint Authorities for Rulemaking on Unmanned Systems) to provide drone operators a methodology for the risk assessment required to apply for an authorization to operate an Unmanned Aircraft System (#UAS) within the specific category.


The SORA proposes risk barriers to prevent the operation from going out of control and provides harm barriers in case the operation does get out of control (e.g. an emergency response plan). The SORA process starts with defining an operational volume by the operator in which the drone operation takes place. This operational volume is related to airspace adjacent to it and the surrounding area on the ground. The SORA includes both a Ground Risk Model and an Air Risk Model to determine risks to the surrounding area and the adjacent airspace, and to propose mitigating measures that can decrease those risks.

The SORA provides drone operators with the risk assessment methodology required to support the application for an authorization of a drone operation in the Specific Category.

In this article we will tell you more about the methodology behind the SORA and how this can help you set up an Operating Manual for your drone operation.


The Concept of Operations (ConOps)


The first step in the SORA process is describing the Concept of Operations (#ConOps) for the drone operation that you want to carry out. This ConOps requires you to collect and provide sufficient technical, operational and human information related to the intended use of the UAS. The ConOps should not only be a description of your operation but also provide insight into the operational safety culture at the organization.


Basically you will need to describe the who's, what's and where's of the operation that you intend to carry out. For this you will need information about the drone and supporting equipment that will be used, you will need to know who will pilot the drone (and what his/her qualifications are), how the organization will make sure that the operation is conducted safely and where the operation will take place (e.g. the airspace classification and the area that will be overflown).


Determining the Ground Risk Class (GRC)


The UAS ground risk relates to the unmitigated risk of a person being struck by the drone (in case of loss of control) and is represented in the SORA by eleven Ground Risk Classes (#GRC). The initial GRC is derived only from the dimensions and kinetic energy of the drone, the type of operation (#VLOS or #BVLOS) and the operational scenario (operations over an unpopulated or populated area, if the area is controlled or if the area includes a gathering of people).


The unmitigated risk of a person being struck by the UAS can be controlled and reduced by means of mitigations. This can, for example, be done by having an effective Emergency Response Plan (#ERP) in place. It is also possible to reduce the GRC by the limiting the effect of the ground impact of the drone by installing an emergency parachute. A third option is to have effective technical containments in place (e.g. active geofencing).


Each risk mitigation (or lack off) provides the you with a factor (+1 to -4) that can be added to the initial GRC to determine the final Ground Risk Class. When the final GRC is determined, the next step is to look at the air risks for the operation.


Determining the Air Risk Class (ARC)


The Air Risk Class (#ARC) is a generalized qualitative classification of the rate at which a drone would encounter a manned aircraft in a typical civil airspace. It provides an initial indication of the collision risk for the airspace, before mitigations are applied. The ARC can found by answering questions in the SORA flow chart about the altitude of the operation, if the operation is in controlled or uncontrolled airspace, if the operation takes place near an airport and if urban or rural areas are overflown.


The flow chart will tell the you what the initial ARC (A - D) is for the intended operation. However, the ARC is a generalized classification, so you - the operator could - consider that the qualification is too high for the conditions within the intended operational volume. If this is the case you can apply strategic and tactical mitigations to lower the ARC.


Strategic mitigation generally consists of procedures and operational restrictions aimed at mitigating risk by reducing the drones encounter rate, or time of exposure, prior to take-off. Strategic mitigations are divided between mitigation which can be controlled by the operator (strategic mitigation by operational restrictions) and those which cannot (strategic mitigation by structures and rules).


Tactical mitigation generally consists of mitigations that are applied after takeoff and take the form of a “mitigating feedback loop.” A mitigating feedback loop is a dynamic system employed to reduce the rate of collision by continuously modifying the geometry and dynamics of aircraft in conflict in an airspace, based on updated aircraft conflict information such as air traffic control (#ATC) traffic alert and collision avoidance system (#TCAS), unmanned traffic management (#UTM and See and Avoid (VLOS).

The Air Risk Class can be reduced by applying strategic and tactical mitigations.

After applying the strategic and tactical mitigations, the final ARC can be determined. Based on the final ARC objectives can be formed to prevent an infringement of the adjacent airspace next to the operational volume. The finial ARC in combination with the final GRC will also determine the Specific Assurance and Integrity Levels based on which Operational Safety Objectives are formed.


What are SAIL and OSO?


Specific Assurance and Integrity Levels (#SAIL) is the chosen parameter in the SORA methodology to consolidate the ground and air risk analysis. The level of confidence represented by the SAIL is not quantitative but instead corresponds to objectives that need to be complied with, descriptions of the activities that might support the compliance with those objectives and evidence to indicate the objectives have been satisfied.


Based on the SAIL (levels I - VI) Operational Safety Objectives (#OSO) are determined for barriers and mitigations to different threats, such as a technical issue with the UAS, a deterioration of external supporting systems, human error and adverse operating conditions. These OSO's basically describe the requirements for the operators organization, the drone and the pilot.


For the pilot requirements will be set on the knowledge and skill-levels he has to possess. These can be obtained by taking the right theoretical and practical drone training. Having the right drone and equipment is crucial for conducting a safe operation, the OSO also describe the requirements for the technical assessment of the drone, equipment and service. The organization itself needs a SORA compliant Operating Manual to have the right procedures in place to safely and efficiently perform its drone operations.



Writing a SORA compliant Operating Manual


A professional Operating Manual is essential in setting up a safe and efficient drone operation. At AirHub we have written Operating Manuals for many different organizations in various industries. And although every organization and drone operation is different, we have identified a number of need-to-haves for a SORA compliant Operating Manual.

A professional Operating Manual is essential to setting up a safe and efficient drone operation.

The first requirement is to make sure that your manual is properly structured to clearly distinguish general information from your operating procedures and other sections. At AirHub we use a format derived from traditional aviation manuals for this. It is also important to clearly describe the organization behind your flight operation and the assigned responsibilities. A third requirement is to provide enough technical information about the drones, equipment and services used for your operation and maintenance requirements that apply to it.


The core of you operating manual will be the procedures that have to be applied by your personnel. It is very important to develop clear and easy to use standard operating procedures (#SOPs) for all actions from flight planning to post flight data processing. You will have to make sure that all mitigating measures stemming from your SORA analyses are incorporated in your normal, abnormal and emergency procedures.


The last requirement is to provide your personnel with all documentation needed to perform a mission. Make sure they have easy acces to all checklists, forms, etc. A professional Drone Operations Management System will save you lots of time and money with this.


How AirHub can help


At AirHub we have guided many organizations across various industries with setting up a safe, efficient and compliant drone operation. Contact us to take advantage of the experience and expertise of our consultants. They will guide you in applying the SORA risk analyses methodology and in setting up an operating manual specific to your operation. And with our AirHub Drone Operations Management platform you will be able to gain a comprehensive insight into your drone operation.