The European Union Aviation Safety Agency has recently published several EASA Means of Compliance for low and medium risk, and the agency is presently soliciting outside feedback on various additional Means of Compliance. But what do they entail, and what exactly does the term refer to?
In the field of aviation, guidelines are formulated to oversee the creation and assembly of aircraft. For example, CS-23 (Certification Specifications 23) set forth the criteria for lightweight aircraft. These Specifications boast an extensive reach as they encompass a diverse array of aircraft that fall under a specific size and weight threshold.
Understanding Compliance Methods and Categories
To promote consistent law application and ensure legal clarity, EASA releases AMC – Acceptable Means of Compliance, which, while not mandatory, are used to show adherence to the legal requirements in place. For example, many standards outlined in CS-23 Amendment 5 serve as AMC for fulfilling CS-23 requirements.
Given their non-obligatory nature, companies have the flexibility to suggest their unique methods to meet the regulations, known as AltMoC – Alternative Means of Compliance. However, these alternative methods require approval from the relevant authorities.
The SC Light-UAS (Special Condition Light Unmanned Aircraft Systems) for High-Risk to Medium Risk categories were rolled out in 2020 and 2021. These Specifications focus on the airworthiness criteria for drones used in specifically classified categories. The AMCs that deal with technical stipulations from SC Light-UAS for medium risk are referred to as Means of Compliance or MoCs.
The Applicability of the Means of Compliance
MoCs typically have a distinctly outlined scope of applicability. For instance, a Means of Compliance relevant for drones smaller than 1 meter may not be suitable for larger models. In the framework of the Specific Operations Risk Assessment (SORA), comprehending the relevance of the Means of Compliance before employing this MoC is crucial. The SORA, crafted by the Joint Authorities for Rulemaking of Unmanned Systems (JARUS SORA), is a strategy used for analyzing drone-related risks. This process helps authorities determine the safety norms for drone operations.
EASA has embraced SORA as an Acceptable Means of Compliance for flights in a specific category. Within this system, operations are classified based on their ground and air risks. The Specific Assurance and Integrity Level (SAIL), scored between I and VI, is assessed based on operational hazards. Certain Means of Compliance may be pertinent for lower SAILs but not for higher ones or vice versa. Therefore, the first critical step should be a thorough evaluation of the MoC’s applicability.
Particular Requirements for Light Unmanned Aerial Systems
Technical requirements stemming from SORA up to SAIL III undergo scrutiny by the national aviation authorities, though certain aspects might necessitate a Design Verification from EASA. For operations falling under SAIL IV, the process of Design Verification is employed by EASA to ensure adherence to the SC Light-UAS medium risk standards. In contrast, operations characterized by SAIL V and VI will compel a type certificate, drawing on the SC Light-UAS high-risk parameters.
This Special Condition for high-risk and medium-risk categories were presented for a more objective-centric certification specification. This was a deviation from previous guidelines, which heavily leaned on the prescriptive norms of manned aircraft certification specifications.
Applicable to drones and not designed for human transport, this Special Condition applies to activities within the specific category involving drones with a weight limit of up to 600 kg. Its ambit is considerably vast, encompassing a wide variety of drones operating in numerous distinct scenarios.
The Means of Compliance With SC Light-UAS.2510
The Means of Compliance related to SC Light-UAS.2510 is frequently regarded as a central segment of UAS regulations to access SAIL IV operations. While it specifically addresses the requirement of SC Light-UAS.2510, its significance extends to safety and system design analyses, ensuring zero fatalities during malfunctions or failures within any aircraft subsystems. This particular Means of Compliance underwent external review until August 31, 2023, for SAIL IV operations and has not yet been published.
There is a growing consensus that this MoC will soon bolster legal certainty for drone operations above populated areas within EASA jurisdictions. The suggested Means of Compliance for SAIL IV stipulates compliance through a Functional Hazard Assessment as per EUROCAE ED-280 standards, coupled with a Design and Installation Appraisal conforming to ASTM F3309-21.
The Means of Compliance With SC Light-UAS.2511
The Means of Compliance, unveiled in May 2022, outlines a method for adhering to the enhanced containment requirements as per the SORA guidelines. Its application is declarative in nature within the context of SAIL II, catering to drones with characteristic dimensions up to 3 meters and kinetic energy not exceeding 34 kJ. In such instances, applicants can formally assert their adherence to this MoC with their respective national aviation authorities.
This MoC specifically tackles the issue of achieving enhanced containment through the use of an autonomous Flight Termination System. It elaborates on the segregation strategies for the system and delineates the methodologies for its testing, categorizing them into four distinct types. Another crucial aspect covered by this MoC is its influence on the determination of the buffer zone’s dimensions within the SORA structure, as it also mandates the specifications for this area when this particular Means of Compliance is invoked.
For operations categorized above SAIL II and for unmanned aerial vehicles exceeding the size of 3 meters, this MoC remains a viable option for applicants. However, its implementation in these circumstances requires EASA to conduct a thorough assessment of the system’s compliance and the robustness of the testing phases through a Design Verification Process.
The Means of Compliance With SC Light-UAS.2512
This Means of Compliance outlines methods for meeting SORA guidelines, focusing on reducing risk factors related to the lethal potential or size of a drone’s hazardous crash zone (known as M2 Mitigation). It presents three methods:
- Justifying a reduction of the critical area by 90% to lessen the risk. (type 1)
- Lowering the probability of fatal injury by 90% to reduce lethality. (type 2)
- A combined method that cuts overall risk by 90% through both of the above strategies.(type 3)
Moreover, the document provides four illustrative instances of achieving type 1, 2, and 3 risk reductions, either through the deployment of a parachute system or by mitigating risks associated with low kinetic energy. While applicants can declare this MoC, they are obliged to substantiate their claims with concrete evidence, as stipulated within the directives. This process ensures that the risk reduction techniques employed are both verifiable and in strict accordance with the outlined requirements.
The Functional Test-Based Means of Compliance with SC Light-UAS
The Functional Test-Based Means of Compliance for SC Light-UAS applies to SAIL III operations or when coordinated with EASA for Design Verification. It references ASTM Standard F3478-20, requiring over 3000 flight hours of UAS testing for SAIL III. This method specifies SC Light-UAS requirements met by such testing, though it doesn’t cover all Special Condition aspects. Essentially, it emphasizes safety through practical testing while upholding broader SC Light-UAS standards, ensuring a reliable foundation for drone use.
The Means of Compliance with Light-UAS.2615, Light-UAS.2405, and Light-UAS.2410
The current MoCs were undergoing external review until September 11, 2023, and are now necessary for SAIL IV’s Design Verification. These MoCs, focusing on Lift, Thrust, and Power Systems, reference the ASTM Standard F3298-19. This standard, known for guiding the design, construction, and verification of Lightweight Unmanned Aircraft Systems, is critical for demonstrating compliance. It provides a clear framework for validating the safety and reliability of key drone systems, ensuring adherence to the high safety standards required for operation within SAIL IV categories.
Future of the EASA Means of Compliance
Recent progress in MoCs is enhancing legal clarity for drone flights over people in Europe. While these developments help ensure safety and compliance, some SC Light-UAS requirements still lack specific MoCs, highlighting the need for more regulatory work and standardization. This ongoing effort is vital for a robust legal structure that fully safeguards drone activities for everyone involved.
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