Before starting the SORA analysis, it is necessary to check that, firstly, the operation does not fall into the “open” category. Next, whether the operation is not covered by a standard scenario in the Annex to Regulation 2019/947 or one of the national standard scenarios. The possible coverage of the operation by a PDRA, a pre-defined risk assessment published by EASA, should also be assessed. The inclusion of an operation from the SORA analysis will also trigger a situation where the operation falls into the ‘certified’ category or the operation is subject to a specific prohibition issued by the competent authority. Only if neither of the above cases applies should the SORA process be applied.
The SORA analysis process then focuses on defining the characteristics of the operation, i.e. where, when and how the unmanned aircraft system (drone) operation will take place. Only in a further step is a ground risk assessment made, which consists of evaluating the risks associated with the operation in terms of human safety on the ground and the risk of collision with manned aircraft.
The above stage is a description of the ConOps. It requires the applicant to collect and present the relevant technical, operational and systems information necessary to assess the risks associated with the intended operation of the unmanned aircraft. The ConOps description forms the basis for all other activities and should be as accurate and detailed as possible. ConOps should not only describe the operation, but also provide insight into the operator’s operational safety culture. They should also include how and when the interaction with the air navigation service provider will take place. Therefore, when defining ConOps, the operator should give due consideration to all steps, mitigation measures and CSOs.
As stated in AMC1 to Article 11 of Regulation 2019/947, the development of ConOps may be an iterative process (adopting successive versions) and therefore, as the SORA process is applied, additional mitigation measures and constraints may be identified, requiring additional related technical details, procedures and other information to be provided or updated in the ConOps. This should culminate in the development of comprehensive ConOps that fully and accurately describe the proposed operation as intended.
The next step in the SORA analysis process is to define the Ground Risk Class (GRC), which consists of defining the risk on the ground associated with hitting people on the ground in the event of loss of control of the UAV. Before selecting the corresponding GRC class, it is necessary to determine the ground impact energy, the largest characteristic dimension and to know the operational scenario.
In principle, in determining the initial GRC, it is possible to use qualitative criteria or quantitative criteria, or consider both, to assess whether an operation is safe. In particular, consideration should be given to whether the operation takes place in sparsely populated areas, densely populated areas or over congregations of people, the concept of a congregation being defined in the legislation and should not be equated with congregations within the meaning of the Polish provisions of the Law on Assemblies.
According to GM1 (advisory material) to Article 2(3) of Regulation 2019/947, assemblies of persons are defined by an objective criterion related to the ability of individuals to move freely. In reality, it is difficult to determine the number of persons above which a group of people can be understood as an assembly in the sense of the UAV regulations. Examples of assemblies of people include sporting, cultural, religious or political events, beaches or parks on a sunny day, shopping streets during shop opening hours, or ski resorts. It may be the case that even a small number of people, due to their inability to move freely, would be considered an assembly in the above sense.
Thus, an operation should be classified as taking place over a populated area if the area taken into account in determining the GRC does not include congregations of people in the above sense and includes areas that are substantially used for residential, commercial or recreational purposes.
The next step, once the initial risk level has been established, will be to determine the final GRC. For this purpose, mitigation measures (mitigations) are applied. The mitigation measures used to modify the initial GRC have a direct impact on the safety objectives associated with a specific operation. This is particularly relevant when technical mitigation measures related to ground risk are applied, such as, for example, an emergency parachute.
If the GRC is too high, measures should be taken to reduce it, i.e. to determine the final risk class on the ground. This can be done by changing operational characteristics, such as the functions of the unmanned aircraft or the flight conditions. Appropriate mitigation strategies can also be implemented.
The SORA analysis distinguishes three levels of application of methods to mitigate the risks associated with a drone collision with the ground. These are: M1 (strategic level, strategic ground risk mitigation) which are solutions applied prior to the start of operations to reduce the number of people potentially exposed to the risks of a BSP operation; M2 (ground impact mitigation level, ground impact effects are reduced) denoting solutions to reduce the severity of failures leading to BSP collisions with the ground; and M3 (Emergency Response Plan/ERP) which is an acknowledgement of operator competence. When, despite the application of mitigation measures (mitigation), the final GRC exceeds 7 the SORA methodology cannot be applied and the operation should be classified as certified.
In this context, attention should be paid to the terms defining the area ‘occupied’ in relation to the performance of a specific operation. This is first of all the flight space, meaning the volume of airspace defined spatially and temporally in which the operator of an unmanned aircraft system plans to perform an operation under the normal procedures described in point 6(c) in Appendix 5 of the Annex to Regulation 2019/947. To this area must be added the safety space, i.e. the volume of airspace beyond the flight space in which the safety procedures described in point 6(d) in Appendix 5 of the Annex to Regulation 2019/947 apply. Together, these two areas (the combination of flight space and safety space) give the operational space. To this must be added the ground risk buffer, meaning the area above the Earth’s surface that surrounds the operational space and which has been defined to minimise the risk to third parties on the surface in the event of an unmanned aircraft leaving the operational space.
