Unmanned Aerial Systems

Within this specific category, Unmanned Aircraft Systems or UAS, the complexity of the certification process rises exponentially.

Any operation of UAS is subject to a previous risk assessment called SORA (Specific Operations Risk Assessment).

Once the SORA has been completed, the Specific Assurance and Integrity Levels (SAIL) are defined.

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The complexity of the operational approval process increases dramatically as the intrinsic risk of the operation (low, medium or high) increases. The required level of robustness for any risk mitigation or operational safety objective is linked with such intrinsic risk.

Within the “Specific” category, the applicant of an operational approval request must collect and provide the relevant technical, operational and system information needed to assess the risks associated with the intended operation of the UAS. The SORA process provides the framework for the assessment of such risk by a logical process to analyze the proposed Concept of Operations, or CONOP, and establish an adequate level of confidence that the operation can be conducted with an acceptable level of risk. Within the SORA process, the Specific Assurance and Integrity Levels (SAIL) drive the robustness of the operational safety objectives (OSO).

For medium risk, compliance with EASA SC Light UAS.2510 and 2511 a can be performed through a relevant safety analysis such as “UAS level FHA” and a “Loss of Containment analysis” to identify failures and combination of failures which could lead to operations outside the operational volume.

Key aspects to perform a Loss of Containment Analysis

For medium risk UAS, regulators are considering the use of extensive evidence from functional tests among the means of compliance with loss of control of operations. However, the amount of hours required for this extensive testing (in the order of 3,000 hours for SAILIII) might require a huge effort and time. An alternative which can be proposed is either complementing or replacing such testing by a safety analysis aimed to show that the loss of control of operation meets the regulator’s expectations. This might be achieved by the use of FHA techniques (at UAS level or system level) to identify the failures and combination of failures that could lead to loss of control of operation, along with qualitative and/or quantitative Fault Tree Analysis and Common Mode Analysis.