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Reconceptualizing Aircraft Certification: A Risk-Based Approach

Updated: May 19

FAA Safety Continuum


In previous discussions, we have examined the drone initiatives by regulatory bodies such as the FAA and EASA, which have implemented progressive tools for drone operations that have begun to show promising results. Despite these advancements, the aviation industry's regulatory framework often adopts a "one size fits all" approach to certifying diverse products. This method, predominantly applied to larger Part 25 airplanes operating under Part 121, has significantly contributed to making aviation one of the safest modes of transportation. However, it does not uniformly enhance safety or benefit the industry when applied across various aviation sectors.

For example, this limitation becomes particularly apparent with the introduction of emerging technologies such as electric Vertical Takeoff and Landing (eVTOL) aircraft. The conventional regulatory approach frequently imposes stringent standards devised for 200-passenger jets onto much smaller, four-passenger eVTOLs. This approach is misguided as it fails to consider these newer aircraft types' unique operational contexts and technical specifications. Uniformly applying transport-level requirements to these smaller category aircraft can inadvertently diminish safety levels for several reasons:

  1. Heavy-duty requirements can inflate manufacturers' costs, potentially forcing compromises incorporating advanced safety features crucial for eVTOLs' specific operational needs.

  2. The operational demands and risk profiles of eVTOLs significantly differ from those of large transport airplanes. The broad application of Part 25/121 requirements fails to recognize these differences, potentially leading to regulations that do not effectively address the unique challenges and risks associated with smaller, urban, or less intensive flight operations.

These observations underscore the need for a more customized regulatory framework that recognizes and adapts to different aircraft types' specific characteristics and safety needs, particularly new entrants like eVTOLs and drones. Such a framework should ensure that safety enhancements are both relevant and cost-effective.

This article explores essential considerations for the evolving landscape of drone technology, highlighting the need for regulatory agility that can accommodate rapid technological advancements while maintaining high safety standards. The goal is to create a regulatory environment supporting innovation and addressing emerging aerial technologies' distinct safety and operational needs.


Understanding the Safety Continuum

Historically, the aviation community has acknowledged the existence of a safety continuum from the industry's inception. This continuum is particularly evident in the varied certification processes for commercial and personal aircraft use. Recent changes, like the shift in Part 23 to performance-based criteria, illustrate a move towards recognizing and addressing these variations. Despite these changes, the pace of technological innovation demands a more sophisticated approach to regulatory oversight that effectively balances risk with safety benefits.

The concept of the safety continuum in aviation is multifaceted, similar to structural substantiation or system safety. Safety in aviation is achieved by appropriately combining various variables to maintain an acceptable overall level of safety. This comprehensive approach is reflected in airline transportation's current safety standards, resulting from concerted efforts in maintenance, air traffic control, operational rules, pilot training, and aircraft certification. Simply focusing on one component of the aircraft—or even the entire aircraft—does not guarantee operational safety.

Several factors contribute to ensuring overly safe operations. These include:

  • The specific mission of the aircraft

  • Frequency of flights

  • Maintenance schedules required

  • Operational environments

  • The experience and training of the pilot

  • Size and composition of the crew

The Sweet Spot

The Figure illustrates the concept of the "Safety Continuum" in the context of system safety and FAA involvement in regulatory efforts. It's a graphical representation depicting the balance that regulatory bodies must strike to ensure adequate safety without overburdening the industry or stifling innovation.

"Risk" is measured on the vertical axis, with positive values indicating increasing risk and negative values suggesting reduced risk. The horizontal axis represents the "Level Of FAA Involvement," with "Less Effort" on the left and "More Effort" on the right. The goal is to find the optimal point of regulatory involvement where safety is maximized and the burden on society is minimized.

The left side of the continuum shows the consequences of "Too little rigor," where insufficient regulatory effort may lead to increased safety escapes and fatal accidents due to an inadequate safety program. This region is marked in red to indicate danger due to under-regulation.

The right side shows the pitfalls of "Too much rigor," where excessive regulation could suppress innovative safety enhancements, misallocate finite resources that could otherwise be used for safety improvements, and potentially increase fatal accidents due to a lack of safety innovation. This area is also marked in red to denote the potential negative impact of over-regulation.

The green zone in the middle is labeled "SEEK." This is the sweet spot that the FAA aims to achieve, where the regulatory approach is balanced. The objective is to achieve safety goals while imposing the least societal burden and minimizing the total risk. This zone indicates the desired state of regulatory involvement, where efforts are sufficient to ensure safety without exceeding what is necessary, allowing for continued innovation and resource allocation efficiency.

Historical Categorization of Risk

Understanding history is important to learn from the past and move forward.

In the 1930s, Civil Aviation Authorities (CAAs) established three fundamental categories for airplanes—Restricted, Normal, and Transport—to streamline regulations as the aviation industry expanded. These categories helped tailor rules for certification and operations, addressing the varied safety issues associated with growing aviation demands. While efficient for many aircraft and operations, this classification system required numerous assumptions that didn't always suit every scenario. However, it functioned well for the majority due to the limited range of aircraft technology and designs available at the time.

By the 1970s, the emergence of CAR 3 and Part 23 aircraft began servicing smaller cities, which paved the way for expanding air services into the 1980s, significantly increasing the number of communities served. The divergence in operational needs between normal and transport categories became evident, leading to the development of the commuter category, which blended Part 23 with specific Part 25 requirements. This new category accommodated the unique requirements of aircraft serving in expanded roles, with capacities ranging from 10-19 passengers and up to 19,000 lbs, applying stringent Part 25 standards to critical safety.

However, by the mid-1990s, the commuter market experienced numerous accidents, highlighting limitations in the era's technology, such as outdated navigation equipment, which was primitive compared to today’s standards. Modern Part 23 aircraft are now equipped with advanced navigation systems like moving maps, terrain warning systems, WAAS GPS, and autopilots with precision ILS capabilities, greatly enhancing safety even in smaller community airports with sophisticated approach systems.

The aviation industry is on the brink of a technological revolution that will affect aircraft utility, operations, and training. The nuances of the safety continuum are more crucial than ever in ensuring the safety of these next-generation aircraft. Recognizing these aspects is essential to creating the right risk categories for drones.

Manned Risk Categories Overview


The Restricted Category encompasses aircraft engaged in non-traditional operations such as external load carrying for helicopters or firebombing in fixed-wing aircraft. Some modern aircraft designed specifically for such missions, like those used in agriculture, still operate under this category, facing higher operational risks than those in normal operations.


Under Part 23/CS 23, the Normal Category is predicated on assumptions suitable for personal, business, and limited commercial use, primarily involving aircraft with simpler gas engine technology and reversible controls. Recent updates to CS 23 and Part 23 facilitate the incorporation of innovations like full-authority flight controls, electric propulsion, and VTOL capabilities, recognizing that historical safety levels may not apply to new technologies and operations. Instead, these rules are designed to adapt and ensure safety effectively across a spectrum of operations, from low to high complexity.

These regulations also accommodate the increasing resemblance of small aircraft operations to those typically seen in high-volume commercial scenarios under Part 121. This evolution calls for a nuanced approach to safety, aligning the certification and operational requirements with the complexity and potential risks of the operations.

Looking forward, the focus on the Normal category, including Light Sport Aircraft (LSA) and Very Light Aircraft (VLA), reflects an understanding that the safety continuum must address a broad range of aircraft types, from drones to large transports, ensuring that each category's specific needs and risks are met with appropriate and effective regulatory measures.

Transport Category

The Transport Category was initially conceptualized to accommodate aircraft such as the DC-3, primarily used for transporting passengers and cargo. These aircraft were designed for commercial service, which typically involves high-volume operations. Given their extensive usage and critical roles, these types of aircraft are subject to very stringent safety standards. They must demonstrate extremely low-risk tolerance and include significant redundancies in their systems, including those involving the pilot and other safety-critical components.

The assumptions underpinning commercial operations influence the certification rules significantly. For instance, the robustness required in the Transport Category reflects the need to ensure the utmost reliability and safety due to the high number of passengers and the variety of operational environments. These stringent requirements differ markedly from those in the Normal Category, which primarily governs Part 91 operations and is tailored for aircraft engaged in less intensive and lower-risk activities. The regulatory framework for the Transport Category is designed to mitigate the increased risks associated with complex operations and larger aircraft, ensuring a higher level of passenger safety and operational integrity.


Expanded Discussion on Drones and Transitional Medium between Part 107 and Part 23

Understanding Part 107

Part 107 of the FAA regulations specifically addresses the operation of small unmanned aircraft systems (UAS) weighing less than 55 pounds, primarily for commercial purposes. This regulation simplifies the process for UAS operators to fly legally in the U.S., providing streamlined requirements focused on operational limitations, and operator certification. The primary emphasis under Part 107 is operational safety without the extensive certification processes required for manned aircraft, recognizing the lower risk posed by small drones than larger, manned aircraft.

The Gap between Part 107 and Part 23

As UAS technology advances and its applications expand into areas traditionally occupied by larger aircraft, a regulatory gap between Part 107 and Part 23 has become evident. Currently addressed by Durability and Reliability Type Certification and Criteria for Making Determination under Exemption 44807, these measures fall short of fully covering the necessary risk profiles and categories. This gap affects operations and aircraft that exceed Part 107 limitations but do not require the full rigor of Part 23 standards, such as larger drones for cargo delivery or passenger transport.

The Safety Continuum for Drones and Emerging Technologies

Multi-Variable Safety Considerations

The safety continuum for drones and the transitional medium between Part 107 and Part 23 involves understanding that safety and risks are functions of multiple variables, as stated before, such as the drone's operational context, technological capabilities, and the intended mission. Variables such as these must be assessed to determine the appropriate level of regulatory oversight and safety requirements:

  • What is the drone's role? Is it for surveillance, delivery, agricultural, or passenger transport?

  • How often and where are the drones operated? Overpopulated areas, over water, or in remote locations?

  • What level of technological sophistication and autonomy are involved? Does the system involve advanced AI for navigation and collision avoidance?

Bridging Gaps with MOSAIC

The MOSAIC initiative is particularly relevant in addressing the middle ground between traditional LSA regulations and the more stringent Part 23 criteria. It serves as a bridge by:

  • Proposing adjusted certification standards that reflect the safety profiles and technological advancements of modern LSAs and drones.

  • Facilitating a regulatory environment that supports innovation while ensuring safety through tailored oversight levels based on risk and technological complexity.

  • Encouraging the adoption of new technologies by creating flexible, performance-based regulations that accommodate a wide range of aircraft operations.

Future Directions and Considerations

As the FAA continues to roll out MOSAIC regulations, stakeholders must remain engaged in a continuous review process to ensure that the regulations effectively address the evolving landscape of aviation technology. This includes:

  • Regular updates to the criteria for risk and safety assessments to incorporate lessons learned from operational data and technological advancements.

  • Collaboration between regulators, manufacturers, and the aviation community to refine safety standards and certification processes.

  • Emphasis on education and training for pilots and manufacturers to align with the new regulatory frameworks introduced by MOSAIC.

Incorporating these aspects into the regulatory framework ensures that as the aviation industry evolves, particularly at the intersection of LSAs, drones, and other emerging technologies, safety remains paramount while innovation thrives. This approach enhances these aircraft's operational efficacy and safety and supports the broader goals of expanding access to aviation and fostering technological advancements.

Bridging the Regulatory Gap

Creating or refining a regulatory framework to effectively bridge the current gaps requires a carefully balanced approach. This framework should foster innovation and broaden drone technology applications while safeguarding public safety. To achieve this, the framework could incorporate tiered certifications or conditional approvals tailored to the risks associated with various drone sizes, uses, and technological capabilities.

FAA Order 8040.6 can serve as a pivotal tool in this process. It would help define clear risk profiles and categorize them accordingly. Once these risk categories are established, they can directly inform the corresponding certification requirements and the necessary level of regulatory rigor. This method ensures that the framework is both adaptive and precise, facilitating safe innovation in drone technology.


In conclusion, the rapidly evolving aviation landscape, highlighted by introducing eVTOLs and advanced drone technologies, necessitates a reevaluation of traditional "one size fits all" regulatory frameworks. While past regulatory practices have undoubtedly established aviation as one of the safest transportation modes, they often fall short when applied to newer, more diverse aviation technologies. The misapplication of stringent, large aircraft standards to smaller, innovative eVTOLs exemplifies the critical need for tailored regulatory approaches that address unique technological and operational nuances.

The historical evolution from traditional aircraft categories to the advent of new technologies underlines the importance of a safety continuum that can adapt to the changing dynamics of aircraft operations and technologies. This adaptive approach should encompass the full spectrum from restricted to transport categories and integrate emerging sectors like unmanned aerial systems. By applying lessons learned from the past, including the successful differentiation of aircraft categories and the expansion of services to smaller communities, the industry can better align current regulations with the realities of modern aviation.

The implementation of the MOSAIC initiative and the utilization of tools such as FAA Order 8040.6 are steps in the right direction. They offer a framework that can bridge the gap between outdated regulatory models and the needs of contemporary aviation technologies. By fostering a regulatory environment that supports innovation while ensuring safety through risk-based oversight and flexible, performance-oriented rules, the aviation industry can continue to thrive.

As we move forward, continuous engagement with all stakeholders—regulators, manufacturers, operators, and the broader aviation community—is essential to refine safety standards and adapt certification processes to the emerging technologies of the 21st century. This collaborative effort will enhance the operational efficacy and safety of new aircraft and support broader goals of expanding access to aviation and fostering technological advancements. The future of aviation regulation lies in its ability to be as dynamic and versatile as the technologies it aims to govern.


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